git-fast-import.html

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 441 <body class="manpage">
 442 <div id="header">
 443 <h1>git-fast-import(1) Manual Page</h1>
 444 <h2 id="_name">NAME</h2>
 445 <div class="sectionbody">
 446 <p>git-fast-import - Backend for fast Git data importers</p>
 447 </div>
 448 </div>
 449 <div id="content">
 450 <div class="sect1">
 451 <h2 id="_synopsis">SYNOPSIS</h2>
 452 <div class="sectionbody">
 453 <div class="verseblock">
 454 <pre class="content">frontend | <em>git fast-import</em> [&lt;options&gt;]</pre>
 455 </div>
 456 </div>
 457 </div>
 458 <div class="sect1">
 459 <h2 id="_description">DESCRIPTION</h2>
 460 <div class="sectionbody">
 461 <div class="paragraph">
 462 <p>This program is usually not what the end user wants to run directly.
 463 Most end users want to use one of the existing frontend programs,
 464 which parses a specific type of foreign source and feeds the contents
 465 stored there to <em>git fast-import</em>.</p>
 466 </div>
 467 <div class="paragraph">
 468 <p>fast-import reads a mixed command/data stream from standard input and
 469 writes one or more packfiles directly into the current repository.
 470 When EOF is received on standard input, fast import writes out
 471 updated branch and tag refs, fully updating the current repository
 472 with the newly imported data.</p>
 473 </div>
 474 <div class="paragraph">
 475 <p>The fast-import backend itself can import into an empty repository (one that
 476 has already been initialized by <em>git init</em>) or incrementally
 477 update an existing populated repository.  Whether or not incremental
 478 imports are supported from a particular foreign source depends on
 479 the frontend program in use.</p>
 480 </div>
 481 </div>
 482 </div>
 483 <div class="sect1">
 484 <h2 id="_options">OPTIONS</h2>
 485 <div class="sectionbody">
 486 <div class="dlist">
 487 <dl>
 488 <dt class="hdlist1">--force</dt>
 489 <dd>
 490 <p>Force updating modified existing branches, even if doing
 491 so would cause commits to be lost (as the new commit does
 492 not contain the old commit).</p>
 493 </dd>
 494 <dt class="hdlist1">--quiet</dt>
 495 <dd>
 496 <p>Disable the output shown by --stats, making fast-import usually
 497 be silent when it is successful.  However, if the import stream
 498 has directives intended to show user output (e.g. <code>progress</code>
 499 directives), the corresponding messages will still be shown.</p>
 500 </dd>
 501 <dt class="hdlist1">--stats</dt>
 502 <dd>
 503 <p>Display some basic statistics about the objects fast-import has
 504 created, the packfiles they were stored into, and the
 505 memory used by fast-import during this run.  Showing this output
 506 is currently the default, but can be disabled with --quiet.</p>
 507 </dd>
 508 <dt class="hdlist1">--allow-unsafe-features</dt>
 509 <dd>
 510 <p>Many command-line options can be provided as part of the
 511 fast-import stream itself by using the <code>feature</code> or <code>option</code>
 512 commands. However, some of these options are unsafe (e.g.,
 513 allowing fast-import to access the filesystem outside of the
 514 repository). These options are disabled by default, but can be
 515 allowed by providing this option on the command line.  This
 516 currently impacts only the <code>export-marks</code>, <code>import-marks</code>, and
 517 <code>import-marks-if-exists</code> feature commands.</p>
 518 <div class="literalblock">
 519 <div class="content">
 520 <pre>Only enable this option if you trust the program generating the
 521 fast-import stream! This option is enabled automatically for
 522 remote-helpers that use the `import` capability, as they are
 523 already trusted to run their own code.</pre>
 524 </div>
 525 </div>
 526 </dd>
 527 </dl>
 528 </div>
 529 <div class="sect2">
 530 <h3 id="_options_for_frontends">Options for Frontends</h3>
 531 <div class="dlist">
 532 <dl>
 533 <dt class="hdlist1">--cat-blob-fd=&lt;fd&gt;</dt>
 534 <dd>
 535 <p>Write responses to <code>get-mark</code>, <code>cat-blob</code>, and <code>ls</code> queries to the
 536 file descriptor &lt;fd&gt; instead of <code>stdout</code>.  Allows <code>progress</code>
 537 output intended for the end-user to be separated from other
 538 output.</p>
 539 </dd>
 540 <dt class="hdlist1">--date-format=&lt;fmt&gt;</dt>
 541 <dd>
 542 <p>Specify the type of dates the frontend will supply to
 543 fast-import within <code>author</code>, <code>committer</code> and <code>tagger</code> commands.
 544 See &#8220;Date Formats&#8221; below for details about which formats
 545 are supported, and their syntax.</p>
 546 </dd>
 547 <dt class="hdlist1">--done</dt>
 548 <dd>
 549 <p>Terminate with error if there is no <code>done</code> command at the end of
 550 the stream.  This option might be useful for detecting errors
 551 that cause the frontend to terminate before it has started to
 552 write a stream.</p>
 553 </dd>
 554 </dl>
 555 </div>
 556 </div>
 557 <div class="sect2">
 558 <h3 id="_locations_of_marks_files">Locations of Marks Files</h3>
 559 <div class="dlist">
 560 <dl>
 561 <dt class="hdlist1">--export-marks=&lt;file&gt;</dt>
 562 <dd>
 563 <p>Dumps the internal marks table to &lt;file&gt; when complete.
 564 Marks are written one per line as <code>:markid</code> <code>SHA-1</code>.
 565 Frontends can use this file to validate imports after they
 566 have been completed, or to save the marks table across
 567 incremental runs.  As &lt;file&gt; is only opened and truncated
 568 at checkpoint (or completion) the same path can also be
 569 safely given to --import-marks.</p>
 570 </dd>
 571 <dt class="hdlist1">--import-marks=&lt;file&gt;</dt>
 572 <dd>
 573 <p>Before processing any input, load the marks specified in
 574 &lt;file&gt;.  The input file must exist, must be readable, and
 575 must use the same format as produced by --export-marks.
 576 Multiple options may be supplied to import more than one
 577 set of marks.  If a mark is defined to different values,
 578 the last file wins.</p>
 579 </dd>
 580 <dt class="hdlist1">--import-marks-if-exists=&lt;file&gt;</dt>
 581 <dd>
 582 <p>Like --import-marks but instead of erroring out, silently
 583 skips the file if it does not exist.</p>
 584 </dd>
 585 <dt class="hdlist1">--[no-]relative-marks</dt>
 586 <dd>
 587 <p>After specifying --relative-marks the paths specified
 588 with --import-marks= and --export-marks= are relative
 589 to an internal directory in the current repository.
 590 In git-fast-import this means that the paths are relative
 591 to the .git/info/fast-import directory. However, other
 592 importers may use a different location.</p>
 593 <div class="paragraph">
 594 <p>Relative and non-relative marks may be combined by interweaving
 595 --(no-)-relative-marks with the --(import|export)-marks= options.</p>
 596 </div>
 597 </dd>
 598 </dl>
 599 </div>
 600 </div>
 601 <div class="sect2">
 602 <h3 id="_submodule_rewriting">Submodule Rewriting</h3>
 603 <div class="dlist">
 604 <dl>
 605 <dt class="hdlist1">--rewrite-submodules-from=&lt;name&gt;:&lt;file&gt;</dt>
 606 <dt class="hdlist1">--rewrite-submodules-to=&lt;name&gt;:&lt;file&gt;</dt>
 607 <dd>
 608 <p> Rewrite the object IDs for the submodule specified by &lt;name&gt; from the values
 609 used in the from &lt;file&gt; to those used in the to &lt;file&gt;. The from marks should
 610 have been created by <code>git</code> <code>fast-export</code>, and the to marks should have been
 611 created by <code>git</code> <code>fast-import</code> when importing that same submodule.</p>
 612 <div class="paragraph">
 613 <p>&lt;name&gt; may be any arbitrary string not containing a colon character, but the
 614 same value must be used with both options when specifying corresponding marks.
 615 Multiple submodules may be specified with different values for &lt;name&gt;. It is an
 616 error not to use these options in corresponding pairs.</p>
 617 </div>
 618 <div class="paragraph">
 619 <p>These options are primarily useful when converting a repository from one hash
 620 algorithm to another; without them, fast-import will fail if it encounters a
 621 submodule because it has no way of writing the object ID into the new hash
 622 algorithm.</p>
 623 </div>
 624 </dd>
 625 </dl>
 626 </div>
 627 </div>
 628 <div class="sect2">
 629 <h3 id="_performance_and_compression_tuning">Performance and Compression Tuning</h3>
 630 <div class="dlist">
 631 <dl>
 632 <dt class="hdlist1">--active-branches=&lt;n&gt;</dt>
 633 <dd>
 634 <p>Maximum number of branches to maintain active at once.
 635 See &#8220;Memory Utilization&#8221; below for details.  Default is 5.</p>
 636 </dd>
 637 <dt class="hdlist1">--big-file-threshold=&lt;n&gt;</dt>
 638 <dd>
 639 <p>Maximum size of a blob that fast-import will attempt to
 640 create a delta for, expressed in bytes.  The default is 512m
 641 (512 MiB).  Some importers may wish to lower this on systems
 642 with constrained memory.</p>
 643 </dd>
 644 <dt class="hdlist1">--depth=&lt;n&gt;</dt>
 645 <dd>
 646 <p>Maximum delta depth, for blob and tree deltification.
 647 Default is 50.</p>
 648 </dd>
 649 <dt class="hdlist1">--export-pack-edges=&lt;file&gt;</dt>
 650 <dd>
 651 <p>After creating a packfile, print a line of data to
 652 &lt;file&gt; listing the filename of the packfile and the last
 653 commit on each branch that was written to that packfile.
 654 This information may be useful after importing projects
 655 whose total object set exceeds the 4 GiB packfile limit,
 656 as these commits can be used as edge points during calls
 657 to <em>git pack-objects</em>.</p>
 658 </dd>
 659 <dt class="hdlist1">--max-pack-size=&lt;n&gt;</dt>
 660 <dd>
 661 <p>Maximum size of each output packfile.
 662 The default is unlimited.</p>
 663 </dd>
 664 <dt class="hdlist1">fastimport.unpackLimit</dt>
 665 <dd>
 666 <p>See <a href="git-config.html">git-config(1)</a></p>
 667 </dd>
 668 </dl>
 669 </div>
 670 </div>
 671 </div>
 672 </div>
 673 <div class="sect1">
 674 <h2 id="_performance">PERFORMANCE</h2>
 675 <div class="sectionbody">
 676 <div class="paragraph">
 677 <p>The design of fast-import allows it to import large projects in a minimum
 678 amount of memory usage and processing time.  Assuming the frontend
 679 is able to keep up with fast-import and feed it a constant stream of data,
 680 import times for projects holding 10+ years of history and containing
 681 100,000+ individual commits are generally completed in just 1-2
 682 hours on quite modest (~$2,000 USD) hardware.</p>
 683 </div>
 684 <div class="paragraph">
 685 <p>Most bottlenecks appear to be in foreign source data access (the
 686 source just cannot extract revisions fast enough) or disk IO (fast-import
 687 writes as fast as the disk will take the data).  Imports will run
 688 faster if the source data is stored on a different drive than the
 689 destination Git repository (due to less IO contention).</p>
 690 </div>
 691 </div>
 692 </div>
 693 <div class="sect1">
 694 <h2 id="_development_cost">DEVELOPMENT COST</h2>
 695 <div class="sectionbody">
 696 <div class="paragraph">
 697 <p>A typical frontend for fast-import tends to weigh in at approximately 200
 698 lines of Perl/Python/Ruby code.  Most developers have been able to
 699 create working importers in just a couple of hours, even though it
 700 is their first exposure to fast-import, and sometimes even to Git.  This is
 701 an ideal situation, given that most conversion tools are throw-away
 702 (use once, and never look back).</p>
 703 </div>
 704 </div>
 705 </div>
 706 <div class="sect1">
 707 <h2 id="_parallel_operation">PARALLEL OPERATION</h2>
 708 <div class="sectionbody">
 709 <div class="paragraph">
 710 <p>Like <em>git push</em> or <em>git fetch</em>, imports handled by fast-import are safe to
 711 run alongside parallel <code>git</code> <code>repack</code> <code>-a</code> <code>-d</code> or <code>git</code> <code>gc</code> invocations,
 712 or any other Git operation (including <em>git prune</em>, as loose objects
 713 are never used by fast-import).</p>
 714 </div>
 715 <div class="paragraph">
 716 <p>fast-import does not lock the branch or tag refs it is actively importing.
 717 After the import, during its ref update phase, fast-import tests each
 718 existing branch ref to verify the update will be a fast-forward
 719 update (the commit stored in the ref is contained in the new
 720 history of the commit to be written).  If the update is not a
 721 fast-forward update, fast-import will skip updating that ref and instead
 722 prints a warning message.  fast-import will always attempt to update all
 723 branch refs, and does not stop on the first failure.</p>
 724 </div>
 725 <div class="paragraph">
 726 <p>Branch updates can be forced with --force, but it&#8217;s recommended that
 727 this only be used on an otherwise quiet repository.  Using --force
 728 is not necessary for an initial import into an empty repository.</p>
 729 </div>
 730 </div>
 731 </div>
 732 <div class="sect1">
 733 <h2 id="_technical_discussion">TECHNICAL DISCUSSION</h2>
 734 <div class="sectionbody">
 735 <div class="paragraph">
 736 <p>fast-import tracks a set of branches in memory.  Any branch can be created
 737 or modified at any point during the import process by sending a
 738 <code>commit</code> command on the input stream.  This design allows a frontend
 739 program to process an unlimited number of branches simultaneously,
 740 generating commits in the order they are available from the source
 741 data.  It also simplifies the frontend programs considerably.</p>
 742 </div>
 743 <div class="paragraph">
 744 <p>fast-import does not use or alter the current working directory, or any
 745 file within it.  (It does however update the current Git repository,
 746 as referenced by <code>GIT_DIR</code>.)  Therefore an import frontend may use
 747 the working directory for its own purposes, such as extracting file
 748 revisions from the foreign source.  This ignorance of the working
 749 directory also allows fast-import to run very quickly, as it does not
 750 need to perform any costly file update operations when switching
 751 between branches.</p>
 752 </div>
 753 </div>
 754 </div>
 755 <div class="sect1">
 756 <h2 id="_input_format">INPUT FORMAT</h2>
 757 <div class="sectionbody">
 758 <div class="paragraph">
 759 <p>With the exception of raw file data (which Git does not interpret)
 760 the fast-import input format is text (ASCII) based.  This text based
 761 format simplifies development and debugging of frontend programs,
 762 especially when a higher level language such as Perl, Python or
 763 Ruby is being used.</p>
 764 </div>
 765 <div class="paragraph">
 766 <p>fast-import is very strict about its input.  Where we say SP below we mean
 767 <strong>exactly</strong> one space.  Likewise LF means one (and only one) linefeed
 768 and HT one (and only one) horizontal tab.
 769 Supplying additional whitespace characters will cause unexpected
 770 results, such as branch names or file names with leading or trailing
 771 spaces in their name, or early termination of fast-import when it encounters
 772 unexpected input.</p>
 773 </div>
 774 <div class="sect2">
 775 <h3 id="_stream_comments">Stream Comments</h3>
 776 <div class="paragraph">
 777 <p>To aid in debugging frontends fast-import ignores any line that
 778 begins with # (ASCII pound/hash) up to and including the line
 779 ending <code>LF</code>.  A comment line may contain any sequence of bytes
 780 that does not contain an LF and therefore may be used to include
 781 any detailed debugging information that might be specific to the
 782 frontend and useful when inspecting a fast-import data stream.</p>
 783 </div>
 784 </div>
 785 <div class="sect2">
 786 <h3 id="_date_formats">Date Formats</h3>
 787 <div class="paragraph">
 788 <p>The following date formats are supported.  A frontend should select
 789 the format it will use for this import by passing the format name
 790 in the --date-format=&lt;fmt&gt; command-line option.</p>
 791 </div>
 792 <div class="dlist">
 793 <dl>
 794 <dt class="hdlist1"><code>raw</code></dt>
 795 <dd>
 796 <p>This is the Git native format and is <em>&lt;time&gt;</em> <code>SP</code> <em>&lt;offutc&gt;</em>.
 797 It is also fast-import&#8217;s default format, if --date-format was
 798 not specified.</p>
 799 <div class="paragraph">
 800 <p>The time of the event is specified by <em>&lt;time&gt;</em> as the number of
 801 seconds since the UNIX epoch (midnight, Jan 1, 1970, UTC) and is
 802 written as an ASCII decimal integer.</p>
 803 </div>
 804 <div class="paragraph">
 805 <p>The local offset is specified by <em>&lt;offutc&gt;</em> as a positive or negative
 806 offset from UTC.  For example EST (which is 5 hours behind UTC)
 807 would be expressed in <em>&lt;tz&gt;</em> by &#8220;-0500&#8221; while UTC is &#8220;+0000&#8221;.
 808 The local offset does not affect <em>&lt;time&gt;</em>; it is used only as an
 809 advisement to help formatting routines display the timestamp.</p>
 810 </div>
 811 <div class="paragraph">
 812 <p>If the local offset is not available in the source material, use
 813 &#8220;+0000&#8221;, or the most common local offset.  For example many
 814 organizations have a CVS repository which has only ever been accessed
 815 by users who are located in the same location and time zone.  In this
 816 case a reasonable offset from UTC could be assumed.</p>
 817 </div>
 818 <div class="paragraph">
 819 <p>Unlike the <code>rfc2822</code> format, this format is very strict.  Any
 820 variation in formatting will cause fast-import to reject the value,
 821 and some sanity checks on the numeric values may also be performed.</p>
 822 </div>
 823 </dd>
 824 <dt class="hdlist1"><code>raw-permissive</code></dt>
 825 <dd>
 826 <p>This is the same as <code>raw</code> except that no sanity checks on
 827 the numeric epoch and local offset are performed.  This can
 828 be useful when trying to filter or import an existing history
 829 with e.g. bogus timezone values.</p>
 830 </dd>
 831 <dt class="hdlist1"><code>rfc2822</code></dt>
 832 <dd>
 833 <p>This is the standard date format as described by RFC 2822.</p>
 834 <div class="paragraph">
 835 <p>An example value is &#8220;Tue Feb 6 11:22:18 2007 -0500&#8221;.  The Git
 836 parser is accurate, but a little on the lenient side.  It is the
 837 same parser used by <em>git am</em> when applying patches
 838 received from email.</p>
 839 </div>
 840 <div class="paragraph">
 841 <p>Some malformed strings may be accepted as valid dates.  In some of
 842 these cases Git will still be able to obtain the correct date from
 843 the malformed string.  There are also some types of malformed
 844 strings which Git will parse wrong, and yet consider valid.
 845 Seriously malformed strings will be rejected.</p>
 846 </div>
 847 <div class="paragraph">
 848 <p>Unlike the <code>raw</code> format above, the time zone/UTC offset information
 849 contained in an RFC 2822 date string is used to adjust the date
 850 value to UTC prior to storage.  Therefore it is important that
 851 this information be as accurate as possible.</p>
 852 </div>
 853 <div class="paragraph">
 854 <p>If the source material uses RFC 2822 style dates,
 855 the frontend should let fast-import handle the parsing and conversion
 856 (rather than attempting to do it itself) as the Git parser has
 857 been well tested in the wild.</p>
 858 </div>
 859 <div class="paragraph">
 860 <p>Frontends should prefer the <code>raw</code> format if the source material
 861 already uses UNIX-epoch format, can be coaxed to give dates in that
 862 format, or its format is easily convertible to it, as there is no
 863 ambiguity in parsing.</p>
 864 </div>
 865 </dd>
 866 <dt class="hdlist1"><code>now</code></dt>
 867 <dd>
 868 <p>Always use the current time and time zone.  The literal
 869 <code>now</code> must always be supplied for <em>&lt;when&gt;</em>.</p>
 870 <div class="paragraph">
 871 <p>This is a toy format.  The current time and time zone of this system
 872 is always copied into the identity string at the time it is being
 873 created by fast-import.  There is no way to specify a different time or
 874 time zone.</p>
 875 </div>
 876 <div class="paragraph">
 877 <p>This particular format is supplied as it&#8217;s short to implement and
 878 may be useful to a process that wants to create a new commit
 879 right now, without needing to use a working directory or
 880 <em>git update-index</em>.</p>
 881 </div>
 882 <div class="paragraph">
 883 <p>If separate <code>author</code> and <code>committer</code> commands are used in a <code>commit</code>
 884 the timestamps may not match, as the system clock will be polled
 885 twice (once for each command).  The only way to ensure that both
 886 author and committer identity information has the same timestamp
 887 is to omit <code>author</code> (thus copying from <code>committer</code>) or to use a
 888 date format other than <code>now</code>.</p>
 889 </div>
 890 </dd>
 891 </dl>
 892 </div>
 893 </div>
 894 <div class="sect2">
 895 <h3 id="_commands">Commands</h3>
 896 <div class="paragraph">
 897 <p>fast-import accepts several commands to update the current repository
 898 and control the current import process.  More detailed discussion
 899 (with examples) of each command follows later.</p>
 900 </div>
 901 <div class="dlist">
 902 <dl>
 903 <dt class="hdlist1"><code>commit</code></dt>
 904 <dd>
 905 <p>Creates a new branch or updates an existing branch by
 906 creating a new commit and updating the branch to point at
 907 the newly created commit.</p>
 908 </dd>
 909 <dt class="hdlist1"><code>tag</code></dt>
 910 <dd>
 911 <p>Creates an annotated tag object from an existing commit or
 912 branch.  Lightweight tags are not supported by this command,
 913 as they are not recommended for recording meaningful points
 914 in time.</p>
 915 </dd>
 916 <dt class="hdlist1"><code>reset</code></dt>
 917 <dd>
 918 <p>Reset an existing branch (or a new branch) to a specific
 919 revision.  This command must be used to change a branch to
 920 a specific revision without making a commit on it.</p>
 921 </dd>
 922 <dt class="hdlist1"><code>blob</code></dt>
 923 <dd>
 924 <p>Convert raw file data into a blob, for future use in a
 925 <code>commit</code> command.  This command is optional and is not
 926 needed to perform an import.</p>
 927 </dd>
 928 <dt class="hdlist1"><code>alias</code></dt>
 929 <dd>
 930 <p>Record that a mark refers to a given object without first
 931 creating any new object.  Using --import-marks and referring
 932 to missing marks will cause fast-import to fail, so aliases
 933 can provide a way to set otherwise pruned commits to a valid
 934 value (e.g. the nearest non-pruned ancestor).</p>
 935 </dd>
 936 <dt class="hdlist1"><code>checkpoint</code></dt>
 937 <dd>
 938 <p>Forces fast-import to close the current packfile, generate its
 939 unique SHA-1 checksum and index, and start a new packfile.
 940 This command is optional and is not needed to perform
 941 an import.</p>
 942 </dd>
 943 <dt class="hdlist1"><code>progress</code></dt>
 944 <dd>
 945 <p>Causes fast-import to echo the entire line to its own
 946 standard output.  This command is optional and is not needed
 947 to perform an import.</p>
 948 </dd>
 949 <dt class="hdlist1"><code>done</code></dt>
 950 <dd>
 951 <p>Marks the end of the stream. This command is optional
 952 unless the <code>done</code> feature was requested using the
 953 <code>--done</code> command-line option or <code>feature</code> <code>done</code> command.</p>
 954 </dd>
 955 <dt class="hdlist1"><code>get-mark</code></dt>
 956 <dd>
 957 <p>Causes fast-import to print the SHA-1 corresponding to a mark
 958 to the file descriptor set with <code>--cat-blob-fd</code>, or <code>stdout</code> if
 959 unspecified.</p>
 960 </dd>
 961 <dt class="hdlist1"><code>cat-blob</code></dt>
 962 <dd>
 963 <p>Causes fast-import to print a blob in <em>cat-file --batch</em>
 964 format to the file descriptor set with <code>--cat-blob-fd</code> or
 965 <code>stdout</code> if unspecified.</p>
 966 </dd>
 967 <dt class="hdlist1"><code>ls</code></dt>
 968 <dd>
 969 <p>Causes fast-import to print a line describing a directory
 970 entry in <em>ls-tree</em> format to the file descriptor set with
 971 <code>--cat-blob-fd</code> or <code>stdout</code> if unspecified.</p>
 972 </dd>
 973 <dt class="hdlist1"><code>feature</code></dt>
 974 <dd>
 975 <p>Enable the specified feature. This requires that fast-import
 976 supports the specified feature, and aborts if it does not.</p>
 977 </dd>
 978 <dt class="hdlist1"><code>option</code></dt>
 979 <dd>
 980 <p>Specify any of the options listed under OPTIONS that do not
 981 change stream semantic to suit the frontend&#8217;s needs. This
 982 command is optional and is not needed to perform an import.</p>
 983 </dd>
 984 </dl>
 985 </div>
 986 </div>
 987 <div class="sect2">
 988 <h3 id="_commit"><code>commit</code></h3>
 989 <div class="paragraph">
 990 <p>Create or update a branch with a new commit, recording one logical
 991 change to the project.</p>
 992 </div>
 993 <div class="literalblock">
 994 <div class="content">
 995 <pre>        'commit' SP &lt;ref&gt; LF
 996         mark?
 997         original-oid?
 998         ('author' (SP &lt;name&gt;)? SP LT &lt;email&gt; GT SP &lt;when&gt; LF)?
 999         'committer' (SP &lt;name&gt;)? SP LT &lt;email&gt; GT SP &lt;when&gt; LF
1000         ('encoding' SP &lt;encoding&gt;)?
1001         data
1002         ('from' SP &lt;commit-ish&gt; LF)?
1003         ('merge' SP &lt;commit-ish&gt; LF)*
1004         (filemodify | filedelete | filecopy | filerename | filedeleteall | notemodify)*
1005         LF?</pre>
1006 </div>
1007 </div>
1008 <div class="paragraph">
1009 <p>where <em>&lt;ref&gt;</em> is the name of the branch to make the commit on.
1010 Typically branch names are prefixed with <code>refs/heads/</code> in
1011 Git, so importing the CVS branch symbol <code>RELENG-1_0</code> would use
1012 <code>refs/heads/RELENG-1_0</code> for the value of <em>&lt;ref&gt;</em>.  The value of
1013 <em>&lt;ref&gt;</em> must be a valid refname in Git.  As <code>LF</code> is not valid in
1014 a Git refname, no quoting or escaping syntax is supported here.</p>
1015 </div>
1016 <div class="paragraph">
1017 <p>A <code>mark</code> command may optionally appear, requesting fast-import to save a
1018 reference to the newly created commit for future use by the frontend
1019 (see below for format).  It is very common for frontends to mark
1020 every commit they create, thereby allowing future branch creation
1021 from any imported commit.</p>
1022 </div>
1023 <div class="paragraph">
1024 <p>The <code>data</code> command following <code>committer</code> must supply the commit
1025 message (see below for <code>data</code> command syntax).  To import an empty
1026 commit message use a 0 length data.  Commit messages are free-form
1027 and are not interpreted by Git.  Currently they must be encoded in
1028 UTF-8, as fast-import does not permit other encodings to be specified.</p>
1029 </div>
1030 <div class="paragraph">
1031 <p>Zero or more <code>filemodify</code>, <code>filedelete</code>, <code>filecopy</code>, <code>filerename</code>,
1032 <code>filedeleteall</code> and <code>notemodify</code> commands
1033 may be included to update the contents of the branch prior to
1034 creating the commit.  These commands may be supplied in any order.
1035 However it is recommended that a <code>filedeleteall</code> command precede
1036 all <code>filemodify</code>, <code>filecopy</code>, <code>filerename</code> and <code>notemodify</code> commands in
1037 the same commit, as <code>filedeleteall</code> wipes the branch clean (see below).</p>
1038 </div>
1039 <div class="paragraph">
1040 <p>The <code>LF</code> after the command is optional (it used to be required).  Note
1041 that for reasons of backward compatibility, if the commit ends with a
1042 <code>data</code> command (i.e. it has no <code>from</code>, <code>merge</code>, <code>filemodify</code>,
1043 <code>filedelete</code>, <code>filecopy</code>, <code>filerename</code>, <code>filedeleteall</code> or
1044 <code>notemodify</code> commands) then two <code>LF</code> commands may appear at the end of
1045 the command instead of just one.</p>
1046 </div>
1047 <div class="sect3">
1048 <h4 id="_author"><code>author</code></h4>
1049 <div class="paragraph">
1050 <p>An <code>author</code> command may optionally appear, if the author information
1051 might differ from the committer information.  If <code>author</code> is omitted
1052 then fast-import will automatically use the committer&#8217;s information for
1053 the author portion of the commit.  See below for a description of
1054 the fields in <code>author</code>, as they are identical to <code>committer</code>.</p>
1055 </div>
1056 </div>
1057 <div class="sect3">
1058 <h4 id="_committer"><code>committer</code></h4>
1059 <div class="paragraph">
1060 <p>The <code>committer</code> command indicates who made this commit, and when
1061 they made it.</p>
1062 </div>
1063 <div class="paragraph">
1064 <p>Here <em>&lt;name&gt;</em> is the person&#8217;s display name (for example
1065 &#8220;Com M Itter&#8221;) and <em>&lt;email&gt;</em> is the person&#8217;s email address
1066 (&#8220;cm@example.com&#8221;).  <code>LT</code> and <code>GT</code> are the literal less-than (\x3c)
1067 and greater-than (\x3e) symbols.  These are required to delimit
1068 the email address from the other fields in the line.  Note that
1069 <em>&lt;name&gt;</em> and <em>&lt;email&gt;</em> are free-form and may contain any sequence
1070 of bytes, except <code>LT</code>, <code>GT</code> and <code>LF</code>.  <em>&lt;name&gt;</em> is typically UTF-8 encoded.</p>
1071 </div>
1072 <div class="paragraph">
1073 <p>The time of the change is specified by <em>&lt;when&gt;</em> using the date format
1074 that was selected by the --date-format=&lt;fmt&gt; command-line option.
1075 See &#8220;Date Formats&#8221; above for the set of supported formats, and
1076 their syntax.</p>
1077 </div>
1078 </div>
1079 <div class="sect3">
1080 <h4 id="_encoding"><code>encoding</code></h4>
1081 <div class="paragraph">
1082 <p>The optional <code>encoding</code> command indicates the encoding of the commit
1083 message.  Most commits are UTF-8 and the encoding is omitted, but this
1084 allows importing commit messages into git without first reencoding them.</p>
1085 </div>
1086 </div>
1087 <div class="sect3">
1088 <h4 id="_from"><code>from</code></h4>
1089 <div class="paragraph">
1090 <p>The <code>from</code> command is used to specify the commit to initialize
1091 this branch from.  This revision will be the first ancestor of the
1092 new commit.  The state of the tree built at this commit will begin
1093 with the state at the <code>from</code> commit, and be altered by the content
1094 modifications in this commit.</p>
1095 </div>
1096 <div class="paragraph">
1097 <p>Omitting the <code>from</code> command in the first commit of a new branch
1098 will cause fast-import to create that commit with no ancestor. This
1099 tends to be desired only for the initial commit of a project.
1100 If the frontend creates all files from scratch when making a new
1101 branch, a <code>merge</code> command may be used instead of <code>from</code> to start
1102 the commit with an empty tree.
1103 Omitting the <code>from</code> command on existing branches is usually desired,
1104 as the current commit on that branch is automatically assumed to
1105 be the first ancestor of the new commit.</p>
1106 </div>
1107 <div class="paragraph">
1108 <p>As <code>LF</code> is not valid in a Git refname or SHA-1 expression, no
1109 quoting or escaping syntax is supported within <em>&lt;commit-ish&gt;</em>.</p>
1110 </div>
1111 <div class="paragraph">
1112 <p>Here <em>&lt;commit-ish&gt;</em> is any of the following:</p>
1113 </div>
1114 <div class="ulist">
1115 <ul>
1116 <li>
1117 <p>The name of an existing branch already in fast-import&#8217;s internal branch
1118 table.  If fast-import doesn&#8217;t know the name, it&#8217;s treated as a SHA-1
1119 expression.</p>
1120 </li>
1121 <li>
1122 <p>A mark reference, <code>:</code><em>&lt;idnum&gt;</em>, where <em>&lt;idnum&gt;</em> is the mark number.</p>
1123 <div class="paragraph">
1124 <p>The reason fast-import uses <code>:</code> to denote a mark reference is this character
1125 is not legal in a Git branch name.  The leading <code>:</code> makes it easy
1126 to distinguish between the mark 42 (<code>:42</code>) and the branch 42 (<code>42</code>
1127 or <code>refs/heads/42</code>), or an abbreviated SHA-1 which happened to
1128 consist only of base-10 digits.</p>
1129 </div>
1130 <div class="paragraph">
1131 <p>Marks must be declared (via <code>mark</code>) before they can be used.</p>
1132 </div>
1133 </li>
1134 <li>
1135 <p>A complete 40 byte or abbreviated commit SHA-1 in hex.</p>
1136 </li>
1137 <li>
1138 <p>Any valid Git SHA-1 expression that resolves to a commit.  See
1139 &#8220;SPECIFYING REVISIONS&#8221; in <a href="gitrevisions.html">gitrevisions(7)</a> for details.</p>
1140 </li>
1141 <li>
1142 <p>The special null SHA-1 (40 zeros) specifies that the branch is to be
1143 removed.</p>
1144 </li>
1145 </ul>
1146 </div>
1147 <div class="paragraph">
1148 <p>The special case of restarting an incremental import from the
1149 current branch value should be written as:</p>
1150 </div>
1151 <div class="listingblock">
1152 <div class="content">
1153 <pre>        from refs/heads/branch^0</pre>
1154 </div>
1155 </div>
1156 <div class="paragraph">
1157 <p>The <code>^0</code> suffix is necessary as fast-import does not permit a branch to
1158 start from itself, and the branch is created in memory before the
1159 <code>from</code> command is even read from the input.  Adding <code>^0</code> will force
1160 fast-import to resolve the commit through Git&#8217;s revision parsing library,
1161 rather than its internal branch table, thereby loading in the
1162 existing value of the branch.</p>
1163 </div>
1164 </div>
1165 <div class="sect3">
1166 <h4 id="_merge"><code>merge</code></h4>
1167 <div class="paragraph">
1168 <p>Includes one additional ancestor commit.  The additional ancestry
1169 link does not change the way the tree state is built at this commit.
1170 If the <code>from</code> command is
1171 omitted when creating a new branch, the first <code>merge</code> commit will be
1172 the first ancestor of the current commit, and the branch will start
1173 out with no files.  An unlimited number of <code>merge</code> commands per
1174 commit are permitted by fast-import, thereby establishing an n-way merge.</p>
1175 </div>
1176 <div class="paragraph">
1177 <p>Here <em>&lt;commit-ish&gt;</em> is any of the commit specification expressions
1178 also accepted by <code>from</code> (see above).</p>
1179 </div>
1180 </div>
1181 <div class="sect3">
1182 <h4 id="_filemodify"><code>filemodify</code></h4>
1183 <div class="paragraph">
1184 <p>Included in a <code>commit</code> command to add a new file or change the
1185 content of an existing file.  This command has two different means
1186 of specifying the content of the file.</p>
1187 </div>
1188 <div class="dlist">
1189 <dl>
1190 <dt class="hdlist1">External data format</dt>
1191 <dd>
1192 <p>The data content for the file was already supplied by a prior
1193 <code>blob</code> command.  The frontend just needs to connect it.</p>
1194 <div class="literalblock">
1195 <div class="content">
1196 <pre>        'M' SP &lt;mode&gt; SP &lt;dataref&gt; SP &lt;path&gt; LF</pre>
1197 </div>
1198 </div>
1199 <div class="paragraph">
1200 <p>Here usually <em>&lt;dataref&gt;</em> must be either a mark reference (<code>:</code><em>&lt;idnum&gt;</em>)
1201 set by a prior <code>blob</code> command, or a full 40-byte SHA-1 of an
1202 existing Git blob object.  If <em>&lt;mode&gt;</em> is <code>040000</code>` then
1203 <em>&lt;dataref&gt;</em> must be the full 40-byte SHA-1 of an existing
1204 Git tree object or a mark reference set with <code>--import-marks</code>.</p>
1205 </div>
1206 </dd>
1207 <dt class="hdlist1">Inline data format</dt>
1208 <dd>
1209 <p>The data content for the file has not been supplied yet.
1210 The frontend wants to supply it as part of this modify
1211 command.</p>
1212 <div class="literalblock">
1213 <div class="content">
1214 <pre>        'M' SP &lt;mode&gt; SP 'inline' SP &lt;path&gt; LF
1215         data</pre>
1216 </div>
1217 </div>
1218 <div class="paragraph">
1219 <p>See below for a detailed description of the <code>data</code> command.</p>
1220 </div>
1221 </dd>
1222 </dl>
1223 </div>
1224 <div class="paragraph">
1225 <p>In both formats <em>&lt;mode&gt;</em> is the type of file entry, specified
1226 in octal.  Git only supports the following modes:</p>
1227 </div>
1228 <div class="ulist">
1229 <ul>
1230 <li>
1231 <p><code>100644</code> or <code>644</code>: A normal (not-executable) file.  The majority
1232 of files in most projects use this mode.  If in doubt, this is
1233 what you want.</p>
1234 </li>
1235 <li>
1236 <p><code>100755</code> or <code>755</code>: A normal, but executable, file.</p>
1237 </li>
1238 <li>
1239 <p><code>120000</code>: A symlink, the content of the file will be the link target.</p>
1240 </li>
1241 <li>
1242 <p><code>160000</code>: A gitlink, SHA-1 of the object refers to a commit in
1243 another repository. Git links can only be specified either by SHA or through
1244 a commit mark. They are used to implement submodules.</p>
1245 </li>
1246 <li>
1247 <p><code>040000</code>: A subdirectory.  Subdirectories can only be specified by
1248 SHA or through a tree mark set with <code>--import-marks</code>.</p>
1249 </li>
1250 </ul>
1251 </div>
1252 <div class="paragraph">
1253 <p>In both formats <em>&lt;path&gt;</em> is the complete path of the file to be added
1254 (if not already existing) or modified (if already existing).</p>
1255 </div>
1256 <div class="paragraph">
1257 <p>A <em>&lt;path&gt;</em> can be written as unquoted bytes or a C-style quoted string.</p>
1258 </div>
1259 <div class="paragraph">
1260 <p>When a <em>&lt;path&gt;</em> does not start with a double quote ("), it is an
1261 unquoted string and is parsed as literal bytes without any escape
1262 sequences. However, if the filename contains <code>LF</code> or starts with double
1263 quote, it cannot be represented as an unquoted string and must be
1264 quoted. Additionally, the source <em>&lt;path&gt;</em> in <code>filecopy</code> or <code>filerename</code>
1265 must be quoted if it contains SP.</p>
1266 </div>
1267 <div class="paragraph">
1268 <p>When a <em>&lt;path&gt;</em> starts with a double quote ("), it is a C-style quoted
1269 string, where the complete filename is enclosed in a pair of double
1270 quotes and escape sequences are used. Certain characters must be escaped
1271 by preceding them with a backslash: <code>LF</code> is written as \n, backslash
1272 as \\, and double quote as \". Some characters may optionally be
1273 written with escape sequences: \a for bell, \b for backspace, \f
1274 for form feed, \n for line feed, \r for carriage return, \t for
1275 horizontal tab, and \v for vertical tab. Any byte can be written with
1276 3-digit octal codes (e.g., \033). All filenames can be represented as
1277 quoted strings.</p>
1278 </div>
1279 <div class="paragraph">
1280 <p>A <em>&lt;path&gt;</em> must use UNIX-style directory separators (forward slash <code>/</code>)
1281 and its value must be in canonical form. That is it must not:</p>
1282 </div>
1283 <div class="ulist">
1284 <ul>
1285 <li>
1286 <p>contain an empty directory component (e.g. <code>foo//bar</code> is invalid),</p>
1287 </li>
1288 <li>
1289 <p>end with a directory separator (e.g. <code>foo/</code> is invalid),</p>
1290 </li>
1291 <li>
1292 <p>start with a directory separator (e.g. <code>/foo</code> is invalid),</p>
1293 </li>
1294 <li>
1295 <p>contain the special component . or .. (e.g. <code>foo/./bar</code> and
1296 <code>foo/</code><code>..</code><code>/bar</code> are invalid).</p>
1297 </li>
1298 </ul>
1299 </div>
1300 <div class="paragraph">
1301 <p>The root of the tree can be represented by an empty string as <em>&lt;path&gt;</em>.</p>
1302 </div>
1303 <div class="paragraph">
1304 <p><em>&lt;path&gt;</em> cannot contain NUL, either literally or escaped as \000.
1305 It is recommended that <em>&lt;path&gt;</em> always be encoded using UTF-8.</p>
1306 </div>
1307 </div>
1308 <div class="sect3">
1309 <h4 id="_filedelete"><code>filedelete</code></h4>
1310 <div class="paragraph">
1311 <p>Included in a <code>commit</code> command to remove a file or recursively
1312 delete an entire directory from the branch.  If the file or directory
1313 removal makes its parent directory empty, the parent directory will
1314 be automatically removed too.  This cascades up the tree until the
1315 first non-empty directory or the root is reached.</p>
1316 </div>
1317 <div class="literalblock">
1318 <div class="content">
1319 <pre>        'D' SP &lt;path&gt; LF</pre>
1320 </div>
1321 </div>
1322 <div class="paragraph">
1323 <p>here <em>&lt;path&gt;</em> is the complete path of the file or subdirectory to
1324 be removed from the branch.
1325 See <code>filemodify</code> above for a detailed description of <em>&lt;path&gt;</em>.</p>
1326 </div>
1327 </div>
1328 <div class="sect3">
1329 <h4 id="_filecopy"><code>filecopy</code></h4>
1330 <div class="paragraph">
1331 <p>Recursively copies an existing file or subdirectory to a different
1332 location within the branch.  The existing file or directory must
1333 exist.  If the destination exists it will be completely replaced
1334 by the content copied from the source.</p>
1335 </div>
1336 <div class="literalblock">
1337 <div class="content">
1338 <pre>        'C' SP &lt;path&gt; SP &lt;path&gt; LF</pre>
1339 </div>
1340 </div>
1341 <div class="paragraph">
1342 <p>here the first <em>&lt;path&gt;</em> is the source location and the second
1343 <em>&lt;path&gt;</em> is the destination.  See <code>filemodify</code> above for a detailed
1344 description of what <em>&lt;path&gt;</em> may look like.  To use a source path
1345 that contains SP the path must be quoted.</p>
1346 </div>
1347 <div class="paragraph">
1348 <p>A <code>filecopy</code> command takes effect immediately.  Once the source
1349 location has been copied to the destination any future commands
1350 applied to the source location will not impact the destination of
1351 the copy.</p>
1352 </div>
1353 </div>
1354 <div class="sect3">
1355 <h4 id="_filerename"><code>filerename</code></h4>
1356 <div class="paragraph">
1357 <p>Renames an existing file or subdirectory to a different location
1358 within the branch.  The existing file or directory must exist. If
1359 the destination exists it will be replaced by the source directory.</p>
1360 </div>
1361 <div class="literalblock">
1362 <div class="content">
1363 <pre>        'R' SP &lt;path&gt; SP &lt;path&gt; LF</pre>
1364 </div>
1365 </div>
1366 <div class="paragraph">
1367 <p>here the first <em>&lt;path&gt;</em> is the source location and the second
1368 <em>&lt;path&gt;</em> is the destination.  See <code>filemodify</code> above for a detailed
1369 description of what <em>&lt;path&gt;</em> may look like.  To use a source path
1370 that contains SP the path must be quoted.</p>
1371 </div>
1372 <div class="paragraph">
1373 <p>A <code>filerename</code> command takes effect immediately.  Once the source
1374 location has been renamed to the destination any future commands
1375 applied to the source location will create new files there and not
1376 impact the destination of the rename.</p>
1377 </div>
1378 <div class="paragraph">
1379 <p>Note that a <code>filerename</code> is the same as a <code>filecopy</code> followed by a
1380 <code>filedelete</code> of the source location.  There is a slight performance
1381 advantage to using <code>filerename</code>, but the advantage is so small
1382 that it is never worth trying to convert a delete/add pair in
1383 source material into a rename for fast-import.  This <code>filerename</code>
1384 command is provided just to simplify frontends that already have
1385 rename information and don&#8217;t want bother with decomposing it into a
1386 <code>filecopy</code> followed by a <code>filedelete</code>.</p>
1387 </div>
1388 </div>
1389 <div class="sect3">
1390 <h4 id="_filedeleteall"><code>filedeleteall</code></h4>
1391 <div class="paragraph">
1392 <p>Included in a <code>commit</code> command to remove all files (and also all
1393 directories) from the branch.  This command resets the internal
1394 branch structure to have no files in it, allowing the frontend
1395 to subsequently add all interesting files from scratch.</p>
1396 </div>
1397 <div class="literalblock">
1398 <div class="content">
1399 <pre>        'deleteall' LF</pre>
1400 </div>
1401 </div>
1402 <div class="paragraph">
1403 <p>This command is extremely useful if the frontend does not know
1404 (or does not care to know) what files are currently on the branch,
1405 and therefore cannot generate the proper <code>filedelete</code> commands to
1406 update the content.</p>
1407 </div>
1408 <div class="paragraph">
1409 <p>Issuing a <code>filedeleteall</code> followed by the needed <code>filemodify</code>
1410 commands to set the correct content will produce the same results
1411 as sending only the needed <code>filemodify</code> and <code>filedelete</code> commands.
1412 The <code>filedeleteall</code> approach may however require fast-import to use slightly
1413 more memory per active branch (less than 1 MiB for even most large
1414 projects); so frontends that can easily obtain only the affected
1415 paths for a commit are encouraged to do so.</p>
1416 </div>
1417 </div>
1418 <div class="sect3">
1419 <h4 id="_notemodify"><code>notemodify</code></h4>
1420 <div class="paragraph">
1421 <p>Included in a <code>commit</code> <em>&lt;notes-ref&gt;</em> command to add a new note
1422 annotating a <em>&lt;commit-ish&gt;</em> or change this annotation contents.
1423 Internally it is similar to filemodify 100644 on <em>&lt;commit-ish&gt;</em>
1424 path (maybe split into subdirectories). It&#8217;s not advised to
1425 use any other commands to write to the <em>&lt;notes-ref&gt;</em> tree except
1426 <code>filedeleteall</code> to delete all existing notes in this tree.
1427 This command has two different means of specifying the content
1428 of the note.</p>
1429 </div>
1430 <div class="dlist">
1431 <dl>
1432 <dt class="hdlist1">External data format</dt>
1433 <dd>
1434 <p>The data content for the note was already supplied by a prior
1435 <code>blob</code> command.  The frontend just needs to connect it to the
1436 commit that is to be annotated.</p>
1437 <div class="literalblock">
1438 <div class="content">
1439 <pre>        'N' SP &lt;dataref&gt; SP &lt;commit-ish&gt; LF</pre>
1440 </div>
1441 </div>
1442 <div class="paragraph">
1443 <p>Here <em>&lt;dataref&gt;</em> can be either a mark reference (<code>:</code><em>&lt;idnum&gt;</em>)
1444 set by a prior <code>blob</code> command, or a full 40-byte SHA-1 of an
1445 existing Git blob object.</p>
1446 </div>
1447 </dd>
1448 <dt class="hdlist1">Inline data format</dt>
1449 <dd>
1450 <p>The data content for the note has not been supplied yet.
1451 The frontend wants to supply it as part of this modify
1452 command.</p>
1453 <div class="literalblock">
1454 <div class="content">
1455 <pre>        'N' SP 'inline' SP &lt;commit-ish&gt; LF
1456         data</pre>
1457 </div>
1458 </div>
1459 <div class="paragraph">
1460 <p>See below for a detailed description of the <code>data</code> command.</p>
1461 </div>
1462 </dd>
1463 </dl>
1464 </div>
1465 <div class="paragraph">
1466 <p>In both formats <em>&lt;commit-ish&gt;</em> is any of the commit specification
1467 expressions also accepted by <code>from</code> (see above).</p>
1468 </div>
1469 </div>
1470 </div>
1471 <div class="sect2">
1472 <h3 id="_mark"><code>mark</code></h3>
1473 <div class="paragraph">
1474 <p>Arranges for fast-import to save a reference to the current object, allowing
1475 the frontend to recall this object at a future point in time, without
1476 knowing its SHA-1.  Here the current object is the object creation
1477 command the <code>mark</code> command appears within.  This can be <code>commit</code>,
1478 <code>tag</code>, and <code>blob</code>, but <code>commit</code> is the most common usage.</p>
1479 </div>
1480 <div class="literalblock">
1481 <div class="content">
1482 <pre>        'mark' SP ':' &lt;idnum&gt; LF</pre>
1483 </div>
1484 </div>
1485 <div class="paragraph">
1486 <p>where <em>&lt;idnum&gt;</em> is the number assigned by the frontend to this mark.
1487 The value of <em>&lt;idnum&gt;</em> is expressed as an ASCII decimal integer.
1488 The value 0 is reserved and cannot be used as
1489 a mark.  Only values greater than or equal to 1 may be used as marks.</p>
1490 </div>
1491 <div class="paragraph">
1492 <p>New marks are created automatically.  Existing marks can be moved
1493 to another object simply by reusing the same <em>&lt;idnum&gt;</em> in another
1494 <code>mark</code> command.</p>
1495 </div>
1496 </div>
1497 <div class="sect2">
1498 <h3 id="_original_oid"><code>original-oid</code></h3>
1499 <div class="paragraph">
1500 <p>Provides the name of the object in the original source control system.
1501 fast-import will simply ignore this directive, but filter processes
1502 which operate on and modify the stream before feeding to fast-import
1503 may have uses for this information</p>
1504 </div>
1505 <div class="literalblock">
1506 <div class="content">
1507 <pre>        'original-oid' SP &lt;object-identifier&gt; LF</pre>
1508 </div>
1509 </div>
1510 <div class="paragraph">
1511 <p>where <em>&lt;object-identifier&gt;</em> is any string not containing LF.</p>
1512 </div>
1513 </div>
1514 <div class="sect2">
1515 <h3 id="_tag"><code>tag</code></h3>
1516 <div class="paragraph">
1517 <p>Creates an annotated tag referring to a specific commit.  To create
1518 lightweight (non-annotated) tags see the <code>reset</code> command below.</p>
1519 </div>
1520 <div class="literalblock">
1521 <div class="content">
1522 <pre>        'tag' SP &lt;name&gt; LF
1523         mark?
1524         'from' SP &lt;commit-ish&gt; LF
1525         original-oid?
1526         'tagger' (SP &lt;name&gt;)? SP LT &lt;email&gt; GT SP &lt;when&gt; LF
1527         data</pre>
1528 </div>
1529 </div>
1530 <div class="paragraph">
1531 <p>where <em>&lt;name&gt;</em> is the name of the tag to create.</p>
1532 </div>
1533 <div class="paragraph">
1534 <p>Tag names are automatically prefixed with <code>refs/tags/</code> when stored
1535 in Git, so importing the CVS branch symbol <code>RELENG-1_0-FINAL</code> would
1536 use just <code>RELENG-1_0-FINAL</code> for <em>&lt;name&gt;</em>, and fast-import will write the
1537 corresponding ref as <code>refs/tags/RELENG-1_0-FINAL</code>.</p>
1538 </div>
1539 <div class="paragraph">
1540 <p>The value of <em>&lt;name&gt;</em> must be a valid refname in Git and therefore
1541 may contain forward slashes.  As <code>LF</code> is not valid in a Git refname,
1542 no quoting or escaping syntax is supported here.</p>
1543 </div>
1544 <div class="paragraph">
1545 <p>The <code>from</code> command is the same as in the <code>commit</code> command; see
1546 above for details.</p>
1547 </div>
1548 <div class="paragraph">
1549 <p>The <code>tagger</code> command uses the same format as <code>committer</code> within
1550 <code>commit</code>; again see above for details.</p>
1551 </div>
1552 <div class="paragraph">
1553 <p>The <code>data</code> command following <code>tagger</code> must supply the annotated tag
1554 message (see below for <code>data</code> command syntax).  To import an empty
1555 tag message use a 0 length data.  Tag messages are free-form and are
1556 not interpreted by Git.  Currently they must be encoded in UTF-8,
1557 as fast-import does not permit other encodings to be specified.</p>
1558 </div>
1559 <div class="paragraph">
1560 <p>Signing annotated tags during import from within fast-import is not
1561 supported.  Trying to include your own PGP/GPG signature is not
1562 recommended, as the frontend does not (easily) have access to the
1563 complete set of bytes which normally goes into such a signature.
1564 If signing is required, create lightweight tags from within fast-import with
1565 <code>reset</code>, then create the annotated versions of those tags offline
1566 with the standard <em>git tag</em> process.</p>
1567 </div>
1568 </div>
1569 <div class="sect2">
1570 <h3 id="_reset"><code>reset</code></h3>
1571 <div class="paragraph">
1572 <p>Creates (or recreates) the named branch, optionally starting from
1573 a specific revision.  The reset command allows a frontend to issue
1574 a new <code>from</code> command for an existing branch, or to create a new
1575 branch from an existing commit without creating a new commit.</p>
1576 </div>
1577 <div class="literalblock">
1578 <div class="content">
1579 <pre>        'reset' SP &lt;ref&gt; LF
1580         ('from' SP &lt;commit-ish&gt; LF)?
1581         LF?</pre>
1582 </div>
1583 </div>
1584 <div class="paragraph">
1585 <p>For a detailed description of <em>&lt;ref&gt;</em> and <em>&lt;commit-ish&gt;</em> see above
1586 under <code>commit</code> and <code>from</code>.</p>
1587 </div>
1588 <div class="paragraph">
1589 <p>The <code>LF</code> after the command is optional (it used to be required).</p>
1590 </div>
1591 <div class="paragraph">
1592 <p>The <code>reset</code> command can also be used to create lightweight
1593 (non-annotated) tags.  For example:</p>
1594 </div>
1595 <div class="exampleblock">
1596 <div class="content">
1597 <div class="literalblock">
1598 <div class="content">
1599 <pre>reset refs/tags/938
1600 from :938</pre>
1601 </div>
1602 </div>
1603 </div>
1604 </div>
1605 <div class="paragraph">
1606 <p>would create the lightweight tag <code>refs/tags/938</code> referring to
1607 whatever commit mark <code>:938</code> references.</p>
1608 </div>
1609 </div>
1610 <div class="sect2">
1611 <h3 id="_blob"><code>blob</code></h3>
1612 <div class="paragraph">
1613 <p>Requests writing one file revision to the packfile.  The revision
1614 is not connected to any commit; this connection must be formed in
1615 a subsequent <code>commit</code> command by referencing the blob through an
1616 assigned mark.</p>
1617 </div>
1618 <div class="literalblock">
1619 <div class="content">
1620 <pre>        'blob' LF
1621         mark?
1622         original-oid?
1623         data</pre>
1624 </div>
1625 </div>
1626 <div class="paragraph">
1627 <p>The mark command is optional here as some frontends have chosen
1628 to generate the Git SHA-1 for the blob on their own, and feed that
1629 directly to <code>commit</code>.  This is typically more work than it&#8217;s worth
1630 however, as marks are inexpensive to store and easy to use.</p>
1631 </div>
1632 </div>
1633 <div class="sect2">
1634 <h3 id="_data"><code>data</code></h3>
1635 <div class="paragraph">
1636 <p>Supplies raw data (for use as blob/file content, commit messages, or
1637 annotated tag messages) to fast-import.  Data can be supplied using an exact
1638 byte count or delimited with a terminating line.  Real frontends
1639 intended for production-quality conversions should always use the
1640 exact byte count format, as it is more robust and performs better.
1641 The delimited format is intended primarily for testing fast-import.</p>
1642 </div>
1643 <div class="paragraph">
1644 <p>Comment lines appearing within the <em>&lt;raw&gt;</em> part of <code>data</code> commands
1645 are always taken to be part of the body of the data and are therefore
1646 never ignored by fast-import.  This makes it safe to import any
1647 file/message content whose lines might start with #.</p>
1648 </div>
1649 <div class="dlist">
1650 <dl>
1651 <dt class="hdlist1">Exact byte count format</dt>
1652 <dd>
1653 <p>The frontend must specify the number of bytes of data.</p>
1654 <div class="literalblock">
1655 <div class="content">
1656 <pre>        'data' SP &lt;count&gt; LF
1657         &lt;raw&gt; LF?</pre>
1658 </div>
1659 </div>
1660 <div class="paragraph">
1661 <p>where <em>&lt;count&gt;</em> is the exact number of bytes appearing within
1662 <em>&lt;raw&gt;</em>.  The value of <em>&lt;count&gt;</em> is expressed as an ASCII decimal
1663 integer.  The <code>LF</code> on either side of <em>&lt;raw&gt;</em> is not
1664 included in <em>&lt;count&gt;</em> and will not be included in the imported data.</p>
1665 </div>
1666 <div class="paragraph">
1667 <p>The <code>LF</code> after <em>&lt;raw&gt;</em> is optional (it used to be required) but
1668 recommended.  Always including it makes debugging a fast-import
1669 stream easier as the next command always starts in column 0
1670 of the next line, even if <em>&lt;raw&gt;</em> did not end with an <code>LF</code>.</p>
1671 </div>
1672 </dd>
1673 <dt class="hdlist1">Delimited format</dt>
1674 <dd>
1675 <p>A delimiter string is used to mark the end of the data.
1676 fast-import will compute the length by searching for the delimiter.
1677 This format is primarily useful for testing and is not
1678 recommended for real data.</p>
1679 <div class="literalblock">
1680 <div class="content">
1681 <pre>        'data' SP '&lt;&lt;' &lt;delim&gt; LF
1682         &lt;raw&gt; LF
1683         &lt;delim&gt; LF
1684         LF?</pre>
1685 </div>
1686 </div>
1687 <div class="paragraph">
1688 <p>where <em>&lt;delim&gt;</em> is the chosen delimiter string.  The string <em>&lt;delim&gt;</em>
1689 must not appear on a line by itself within <em>&lt;raw&gt;</em>, as otherwise
1690 fast-import will think the data ends earlier than it really does.  The <code>LF</code>
1691 immediately trailing <em>&lt;raw&gt;</em> is part of <em>&lt;raw&gt;</em>.  This is one of
1692 the limitations of the delimited format, it is impossible to supply
1693 a data chunk which does not have an LF as its last byte.</p>
1694 </div>
1695 <div class="paragraph">
1696 <p>The <code>LF</code> after <em>&lt;delim&gt;</em> <code>LF</code> is optional (it used to be required).</p>
1697 </div>
1698 </dd>
1699 </dl>
1700 </div>
1701 </div>
1702 <div class="sect2">
1703 <h3 id="_alias"><code>alias</code></h3>
1704 <div class="paragraph">
1705 <p>Record that a mark refers to a given object without first creating any
1706 new object.</p>
1707 </div>
1708 <div class="literalblock">
1709 <div class="content">
1710 <pre>        'alias' LF
1711         mark
1712         'to' SP &lt;commit-ish&gt; LF
1713         LF?</pre>
1714 </div>
1715 </div>
1716 <div class="paragraph">
1717 <p>For a detailed description of <em>&lt;commit-ish&gt;</em> see above under <code>from</code>.</p>
1718 </div>
1719 </div>
1720 <div class="sect2">
1721 <h3 id="_checkpoint"><code>checkpoint</code></h3>
1722 <div class="paragraph">
1723 <p>Forces fast-import to close the current packfile, start a new one, and to
1724 save out all current branch refs, tags and marks.</p>
1725 </div>
1726 <div class="literalblock">
1727 <div class="content">
1728 <pre>        'checkpoint' LF
1729         LF?</pre>
1730 </div>
1731 </div>
1732 <div class="paragraph">
1733 <p>Note that fast-import automatically switches packfiles when the current
1734 packfile reaches --max-pack-size, or 4 GiB, whichever limit is
1735 smaller.  During an automatic packfile switch fast-import does not update
1736 the branch refs, tags or marks.</p>
1737 </div>
1738 <div class="paragraph">
1739 <p>As a <code>checkpoint</code> can require a significant amount of CPU time and
1740 disk IO (to compute the overall pack SHA-1 checksum, generate the
1741 corresponding index file, and update the refs) it can easily take
1742 several minutes for a single <code>checkpoint</code> command to complete.</p>
1743 </div>
1744 <div class="paragraph">
1745 <p>Frontends may choose to issue checkpoints during extremely large
1746 and long running imports, or when they need to allow another Git
1747 process access to a branch.  However given that a 30 GiB Subversion
1748 repository can be loaded into Git through fast-import in about 3 hours,
1749 explicit checkpointing may not be necessary.</p>
1750 </div>
1751 <div class="paragraph">
1752 <p>The <code>LF</code> after the command is optional (it used to be required).</p>
1753 </div>
1754 </div>
1755 <div class="sect2">
1756 <h3 id="_progress"><code>progress</code></h3>
1757 <div class="paragraph">
1758 <p>Causes fast-import to print the entire <code>progress</code> line unmodified to
1759 its standard output channel (file descriptor 1) when the command is
1760 processed from the input stream.  The command otherwise has no impact
1761 on the current import, or on any of fast-import&#8217;s internal state.</p>
1762 </div>
1763 <div class="literalblock">
1764 <div class="content">
1765 <pre>        'progress' SP &lt;any&gt; LF
1766         LF?</pre>
1767 </div>
1768 </div>
1769 <div class="paragraph">
1770 <p>The <em>&lt;any&gt;</em> part of the command may contain any sequence of bytes
1771 that does not contain <code>LF</code>.  The <code>LF</code> after the command is optional.
1772 Callers may wish to process the output through a tool such as sed to
1773 remove the leading part of the line, for example:</p>
1774 </div>
1775 <div class="exampleblock">
1776 <div class="content">
1777 <div class="literalblock">
1778 <div class="content">
1779 <pre>frontend | git fast-import | sed 's/^progress //'</pre>
1780 </div>
1781 </div>
1782 </div>
1783 </div>
1784 <div class="paragraph">
1785 <p>Placing a <code>progress</code> command immediately after a <code>checkpoint</code> will
1786 inform the reader when the <code>checkpoint</code> has been completed and it
1787 can safely access the refs that fast-import updated.</p>
1788 </div>
1789 </div>
1790 <div class="sect2">
1791 <h3 id="_get_mark"><code>get-mark</code></h3>
1792 <div class="paragraph">
1793 <p>Causes fast-import to print the SHA-1 corresponding to a mark to
1794 stdout or to the file descriptor previously arranged with the
1795 <code>--cat-blob-fd</code> argument. The command otherwise has no impact on the
1796 current import; its purpose is to retrieve SHA-1s that later commits
1797 might want to refer to in their commit messages.</p>
1798 </div>
1799 <div class="literalblock">
1800 <div class="content">
1801 <pre>        'get-mark' SP ':' &lt;idnum&gt; LF</pre>
1802 </div>
1803 </div>
1804 <div class="paragraph">
1805 <p>See &#8220;Responses To Commands&#8221; below for details about how to read
1806 this output safely.</p>
1807 </div>
1808 </div>
1809 <div class="sect2">
1810 <h3 id="_cat_blob"><code>cat-blob</code></h3>
1811 <div class="paragraph">
1812 <p>Causes fast-import to print a blob to a file descriptor previously
1813 arranged with the <code>--cat-blob-fd</code> argument.  The command otherwise
1814 has no impact on the current import; its main purpose is to
1815 retrieve blobs that may be in fast-import&#8217;s memory but not
1816 accessible from the target repository.</p>
1817 </div>
1818 <div class="literalblock">
1819 <div class="content">
1820 <pre>        'cat-blob' SP &lt;dataref&gt; LF</pre>
1821 </div>
1822 </div>
1823 <div class="paragraph">
1824 <p>The <em>&lt;dataref&gt;</em> can be either a mark reference (<code>:</code><em>&lt;idnum&gt;</em>)
1825 set previously or a full 40-byte SHA-1 of a Git blob, preexisting or
1826 ready to be written.</p>
1827 </div>
1828 <div class="paragraph">
1829 <p>Output uses the same format as <code>git</code> <code>cat-file</code> <code>--batch</code>:</p>
1830 </div>
1831 <div class="exampleblock">
1832 <div class="content">
1833 <div class="literalblock">
1834 <div class="content">
1835 <pre>&lt;sha1&gt; SP 'blob' SP &lt;size&gt; LF
1836 &lt;contents&gt; LF</pre>
1837 </div>
1838 </div>
1839 </div>
1840 </div>
1841 <div class="paragraph">
1842 <p>This command can be used where a <code>filemodify</code> directive can appear,
1843 allowing it to be used in the middle of a commit.  For a <code>filemodify</code>
1844 using an inline directive, it can also appear right before the <code>data</code>
1845 directive.</p>
1846 </div>
1847 <div class="paragraph">
1848 <p>See &#8220;Responses To Commands&#8221; below for details about how to read
1849 this output safely.</p>
1850 </div>
1851 </div>
1852 <div class="sect2">
1853 <h3 id="_ls"><code>ls</code></h3>
1854 <div class="paragraph">
1855 <p>Prints information about the object at a path to a file descriptor
1856 previously arranged with the <code>--cat-blob-fd</code> argument.  This allows
1857 printing a blob from the active commit (with <code>cat-blob</code>) or copying a
1858 blob or tree from a previous commit for use in the current one (with
1859 <code>filemodify</code>).</p>
1860 </div>
1861 <div class="paragraph">
1862 <p>The <code>ls</code> command can also be used where a <code>filemodify</code> directive can
1863 appear, allowing it to be used in the middle of a commit.</p>
1864 </div>
1865 <div class="dlist">
1866 <dl>
1867 <dt class="hdlist1">Reading from the active commit</dt>
1868 <dd>
1869 <p>This form can only be used in the middle of a <code>commit</code>.
1870 The path names a directory entry within fast-import&#8217;s
1871 active commit.  The path must be quoted in this case.</p>
1872 <div class="literalblock">
1873 <div class="content">
1874 <pre>        'ls' SP &lt;path&gt; LF</pre>
1875 </div>
1876 </div>
1877 </dd>
1878 <dt class="hdlist1">Reading from a named tree</dt>
1879 <dd>
1880 <p>The <em>&lt;dataref&gt;</em> can be a mark reference (<code>:</code><em>&lt;idnum&gt;</em>) or the
1881 full 40-byte SHA-1 of a Git tag, commit, or tree object,
1882 preexisting or waiting to be written.
1883 The path is relative to the top level of the tree
1884 named by <em>&lt;dataref&gt;</em>.</p>
1885 <div class="literalblock">
1886 <div class="content">
1887 <pre>        'ls' SP &lt;dataref&gt; SP &lt;path&gt; LF</pre>
1888 </div>
1889 </div>
1890 </dd>
1891 </dl>
1892 </div>
1893 <div class="paragraph">
1894 <p>See <code>filemodify</code> above for a detailed description of <em>&lt;path&gt;</em>.</p>
1895 </div>
1896 <div class="paragraph">
1897 <p>Output uses the same format as <code>git</code> <code>ls-tree</code> <em>&lt;tree&gt;</em> <code>--</code> <em>&lt;path&gt;</em>:</p>
1898 </div>
1899 <div class="exampleblock">
1900 <div class="content">
1901 <div class="literalblock">
1902 <div class="content">
1903 <pre>&lt;mode&gt; SP ('blob' | 'tree' | 'commit') SP &lt;dataref&gt; HT &lt;path&gt; LF</pre>
1904 </div>
1905 </div>
1906 </div>
1907 </div>
1908 <div class="paragraph">
1909 <p>The &lt;dataref&gt; represents the blob, tree, or commit object at &lt;path&gt;
1910 and can be used in later <em>get-mark</em>, <em>cat-blob</em>, <em>filemodify</em>, or
1911 <em>ls</em> commands.</p>
1912 </div>
1913 <div class="paragraph">
1914 <p>If there is no file or subtree at that path, <em>git fast-import</em> will
1915 instead report</p>
1916 </div>
1917 <div class="exampleblock">
1918 <div class="content">
1919 <div class="literalblock">
1920 <div class="content">
1921 <pre>missing SP &lt;path&gt; LF</pre>
1922 </div>
1923 </div>
1924 </div>
1925 </div>
1926 <div class="paragraph">
1927 <p>See &#8220;Responses To Commands&#8221; below for details about how to read
1928 this output safely.</p>
1929 </div>
1930 </div>
1931 <div class="sect2">
1932 <h3 id="_feature"><code>feature</code></h3>
1933 <div class="paragraph">
1934 <p>Require that fast-import supports the specified feature, or abort if
1935 it does not.</p>
1936 </div>
1937 <div class="literalblock">
1938 <div class="content">
1939 <pre>        'feature' SP &lt;feature&gt; ('=' &lt;argument&gt;)? LF</pre>
1940 </div>
1941 </div>
1942 <div class="paragraph">
1943 <p>The &lt;feature&gt; part of the command may be any one of the following:</p>
1944 </div>
1945 <div class="dlist">
1946 <dl>
1947 <dt class="hdlist1">date-format</dt>
1948 <dt class="hdlist1">export-marks</dt>
1949 <dt class="hdlist1">relative-marks</dt>
1950 <dt class="hdlist1">no-relative-marks</dt>
1951 <dt class="hdlist1">force</dt>
1952 <dd>
1953 <p>Act as though the corresponding command-line option with
1954 a leading <code>--</code> was passed on the command line
1955 (see OPTIONS, above).</p>
1956 </dd>
1957 <dt class="hdlist1">import-marks</dt>
1958 <dt class="hdlist1">import-marks-if-exists</dt>
1959 <dd>
1960 <p>Like --import-marks except in two respects: first, only one
1961 "feature import-marks" or "feature import-marks-if-exists"
1962 command is allowed per stream; second, an --import-marks=
1963 or --import-marks-if-exists command-line option overrides
1964 any of these "feature" commands in the stream; third,
1965 "feature import-marks-if-exists" like a corresponding
1966 command-line option silently skips a nonexistent file.</p>
1967 </dd>
1968 <dt class="hdlist1">get-mark</dt>
1969 <dt class="hdlist1">cat-blob</dt>
1970 <dt class="hdlist1">ls</dt>
1971 <dd>
1972 <p>Require that the backend support the <em>get-mark</em>, <em>cat-blob</em>,
1973 or <em>ls</em> command respectively.
1974 Versions of fast-import not supporting the specified command
1975 will exit with a message indicating so.
1976 This lets the import error out early with a clear message,
1977 rather than wasting time on the early part of an import
1978 before the unsupported command is detected.</p>
1979 </dd>
1980 <dt class="hdlist1">notes</dt>
1981 <dd>
1982 <p>Require that the backend support the <em>notemodify</em> (N)
1983 subcommand to the <em>commit</em> command.
1984 Versions of fast-import not supporting notes will exit
1985 with a message indicating so.</p>
1986 </dd>
1987 <dt class="hdlist1">done</dt>
1988 <dd>
1989 <p>Error out if the stream ends without a <em>done</em> command.
1990 Without this feature, errors causing the frontend to end
1991 abruptly at a convenient point in the stream can go
1992 undetected.  This may occur, for example, if an import
1993 front end dies in mid-operation without emitting SIGTERM
1994 or SIGKILL at its subordinate git fast-import instance.</p>
1995 </dd>
1996 </dl>
1997 </div>
1998 </div>
1999 <div class="sect2">
2000 <h3 id="_option"><code>option</code></h3>
2001 <div class="paragraph">
2002 <p>Processes the specified option so that git fast-import behaves in a
2003 way that suits the frontend&#8217;s needs.
2004 Note that options specified by the frontend are overridden by any
2005 options the user may specify to git fast-import itself.</p>
2006 </div>
2007 <div class="literalblock">
2008 <div class="content">
2009 <pre>    'option' SP &lt;option&gt; LF</pre>
2010 </div>
2011 </div>
2012 <div class="paragraph">
2013 <p>The <em>&lt;option&gt;</em> part of the command may contain any of the options
2014 listed in the OPTIONS section that do not change import semantics,
2015 without the leading <code>--</code> and is treated in the same way.</p>
2016 </div>
2017 <div class="paragraph">
2018 <p>Option commands must be the first commands on the input (not counting
2019 feature commands), to give an option command after any non-option
2020 command is an error.</p>
2021 </div>
2022 <div class="paragraph">
2023 <p>The following command-line options change import semantics and may therefore
2024 not be passed as option:</p>
2025 </div>
2026 <div class="ulist">
2027 <ul>
2028 <li>
2029 <p>date-format</p>
2030 </li>
2031 <li>
2032 <p>import-marks</p>
2033 </li>
2034 <li>
2035 <p>export-marks</p>
2036 </li>
2037 <li>
2038 <p>cat-blob-fd</p>
2039 </li>
2040 <li>
2041 <p>force</p>
2042 </li>
2043 </ul>
2044 </div>
2045 </div>
2046 <div class="sect2">
2047 <h3 id="_done"><code>done</code></h3>
2048 <div class="paragraph">
2049 <p>If the <code>done</code> feature is not in use, treated as if EOF was read.
2050 This can be used to tell fast-import to finish early.</p>
2051 </div>
2052 <div class="paragraph">
2053 <p>If the <code>--done</code> command-line option or <code>feature</code> <code>done</code> command is
2054 in use, the <code>done</code> command is mandatory and marks the end of the
2055 stream.</p>
2056 </div>
2057 </div>
2058 </div>
2059 </div>
2060 <div class="sect1">
2061 <h2 id="_responses_to_commands">RESPONSES TO COMMANDS</h2>
2062 <div class="sectionbody">
2063 <div class="paragraph">
2064 <p>New objects written by fast-import are not available immediately.
2065 Most fast-import commands have no visible effect until the next
2066 checkpoint (or completion).  The frontend can send commands to
2067 fill fast-import&#8217;s input pipe without worrying about how quickly
2068 they will take effect, which improves performance by simplifying
2069 scheduling.</p>
2070 </div>
2071 <div class="paragraph">
2072 <p>For some frontends, though, it is useful to be able to read back
2073 data from the current repository as it is being updated (for
2074 example when the source material describes objects in terms of
2075 patches to be applied to previously imported objects).  This can
2076 be accomplished by connecting the frontend and fast-import via
2077 bidirectional pipes:</p>
2078 </div>
2079 <div class="exampleblock">
2080 <div class="content">
2081 <div class="literalblock">
2082 <div class="content">
2083 <pre>mkfifo fast-import-output
2084 frontend &lt;fast-import-output |
2085 git fast-import &gt;fast-import-output</pre>
2086 </div>
2087 </div>
2088 </div>
2089 </div>
2090 <div class="paragraph">
2091 <p>A frontend set up this way can use <code>progress</code>, <code>get-mark</code>, <code>ls</code>, and
2092 <code>cat-blob</code> commands to read information from the import in progress.</p>
2093 </div>
2094 <div class="paragraph">
2095 <p>To avoid deadlock, such frontends must completely consume any
2096 pending output from <code>progress</code>, <code>ls</code>, <code>get-mark</code>, and <code>cat-blob</code> before
2097 performing writes to fast-import that might block.</p>
2098 </div>
2099 </div>
2100 </div>
2101 <div class="sect1">
2102 <h2 id="_crash_reports">CRASH REPORTS</h2>
2103 <div class="sectionbody">
2104 <div class="paragraph">
2105 <p>If fast-import is supplied invalid input it will terminate with a
2106 non-zero exit status and create a crash report in the top level of
2107 the Git repository it was importing into.  Crash reports contain
2108 a snapshot of the internal fast-import state as well as the most
2109 recent commands that lead up to the crash.</p>
2110 </div>
2111 <div class="paragraph">
2112 <p>All recent commands (including stream comments, file changes and
2113 progress commands) are shown in the command history within the crash
2114 report, but raw file data and commit messages are excluded from the
2115 crash report.  This exclusion saves space within the report file
2116 and reduces the amount of buffering that fast-import must perform
2117 during execution.</p>
2118 </div>
2119 <div class="paragraph">
2120 <p>After writing a crash report fast-import will close the current
2121 packfile and export the marks table.  This allows the frontend
2122 developer to inspect the repository state and resume the import from
2123 the point where it crashed.  The modified branches and tags are not
2124 updated during a crash, as the import did not complete successfully.
2125 Branch and tag information can be found in the crash report and
2126 must be applied manually if the update is needed.</p>
2127 </div>
2128 <div class="paragraph">
2129 <p>An example crash:</p>
2130 </div>
2131 <div class="exampleblock">
2132 <div class="content">
2133 <div class="literalblock">
2134 <div class="content">
2135 <pre>$ cat &gt;in &lt;&lt;END_OF_INPUT
2136 # my very first test commit
2137 commit refs/heads/master
2138 committer Shawn O. Pearce &lt;spearce&gt; 19283 -0400
2139 # who is that guy anyway?
2140 data &lt;&lt;EOF
2141 this is my commit
2142 EOF
2143 M 644 inline .gitignore
2144 data &lt;&lt;EOF
2145 .gitignore
2146 EOF
2147 M 777 inline bob
2148 END_OF_INPUT</pre>
2149 </div>
2150 </div>
2151 <div class="literalblock">
2152 <div class="content">
2153 <pre>$ git fast-import &lt;in
2154 fatal: Corrupt mode: M 777 inline bob
2155 fast-import: dumping crash report to .git/fast_import_crash_8434</pre>
2156 </div>
2157 </div>
2158 <div class="literalblock">
2159 <div class="content">
2160 <pre>$ cat .git/fast_import_crash_8434
2161 fast-import crash report:
2162     fast-import process: 8434
2163     parent process     : 1391
2164     at Sat Sep 1 00:58:12 2007</pre>
2165 </div>
2166 </div>
2167 <div class="literalblock">
2168 <div class="content">
2169 <pre>fatal: Corrupt mode: M 777 inline bob</pre>
2170 </div>
2171 </div>
2172 <div class="literalblock">
2173 <div class="content">
2174 <pre>Most Recent Commands Before Crash
2175 ---------------------------------
2176   # my very first test commit
2177   commit refs/heads/master
2178   committer Shawn O. Pearce &lt;spearce&gt; 19283 -0400
2179   # who is that guy anyway?
2180   data &lt;&lt;EOF
2181   M 644 inline .gitignore
2182   data &lt;&lt;EOF
2183 * M 777 inline bob</pre>
2184 </div>
2185 </div>
2186 <div class="literalblock">
2187 <div class="content">
2188 <pre>Active Branch LRU
2189 -----------------
2190     active_branches = 1 cur, 5 max</pre>
2191 </div>
2192 </div>
2193 <div class="literalblock">
2194 <div class="content">
2195 <pre>pos  clock name
2196 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2197  1)      0 refs/heads/master</pre>
2198 </div>
2199 </div>
2200 <div class="literalblock">
2201 <div class="content">
2202 <pre>Inactive Branches
2203 -----------------
2204 refs/heads/master:
2205   status      : active loaded dirty
2206   tip commit  : 0000000000000000000000000000000000000000
2207   old tree    : 0000000000000000000000000000000000000000
2208   cur tree    : 0000000000000000000000000000000000000000
2209   commit clock: 0
2210   last pack   :</pre>
2211 </div>
2212 </div>
2213 <div class="literalblock">
2214 <div class="content">
2215 <pre>-------------------
2216 END OF CRASH REPORT</pre>
2217 </div>
2218 </div>
2219 </div>
2220 </div>
2221 </div>
2222 </div>
2223 <div class="sect1">
2224 <h2 id="_tips_and_tricks">TIPS AND TRICKS</h2>
2225 <div class="sectionbody">
2226 <div class="paragraph">
2227 <p>The following tips and tricks have been collected from various
2228 users of fast-import, and are offered here as suggestions.</p>
2229 </div>
2230 <div class="sect2">
2231 <h3 id="_use_one_mark_per_commit">Use One Mark Per Commit</h3>
2232 <div class="paragraph">
2233 <p>When doing a repository conversion, use a unique mark per commit
2234 (<code>mark</code> <code>:</code><em>&lt;n&gt;</em>) and supply the --export-marks option on the command
2235 line.  fast-import will dump a file which lists every mark and the Git
2236 object SHA-1 that corresponds to it.  If the frontend can tie
2237 the marks back to the source repository, it is easy to verify the
2238 accuracy and completeness of the import by comparing each Git
2239 commit to the corresponding source revision.</p>
2240 </div>
2241 <div class="paragraph">
2242 <p>Coming from a system such as Perforce or Subversion, this should be
2243 quite simple, as the fast-import mark can also be the Perforce changeset
2244 number or the Subversion revision number.</p>
2245 </div>
2246 </div>
2247 <div class="sect2">
2248 <h3 id="_freely_skip_around_branches">Freely Skip Around Branches</h3>
2249 <div class="paragraph">
2250 <p>Don&#8217;t bother trying to optimize the frontend to stick to one branch
2251 at a time during an import.  Although doing so might be slightly
2252 faster for fast-import, it tends to increase the complexity of the frontend
2253 code considerably.</p>
2254 </div>
2255 <div class="paragraph">
2256 <p>The branch LRU builtin to fast-import tends to behave very well, and the
2257 cost of activating an inactive branch is so low that bouncing around
2258 between branches has virtually no impact on import performance.</p>
2259 </div>
2260 </div>
2261 <div class="sect2">
2262 <h3 id="_handling_renames">Handling Renames</h3>
2263 <div class="paragraph">
2264 <p>When importing a renamed file or directory, simply delete the old
2265 name(s) and modify the new name(s) during the corresponding commit.
2266 Git performs rename detection after-the-fact, rather than explicitly
2267 during a commit.</p>
2268 </div>
2269 </div>
2270 <div class="sect2">
2271 <h3 id="_use_tag_fixup_branches">Use Tag Fixup Branches</h3>
2272 <div class="paragraph">
2273 <p>Some other SCM systems let the user create a tag from multiple
2274 files which are not from the same commit/changeset.  Or to create
2275 tags which are a subset of the files available in the repository.</p>
2276 </div>
2277 <div class="paragraph">
2278 <p>Importing these tags as-is in Git is impossible without making at
2279 least one commit which &#8220;fixes up&#8221; the files to match the content
2280 of the tag.  Use fast-import&#8217;s <code>reset</code> command to reset a dummy branch
2281 outside of your normal branch space to the base commit for the tag,
2282 then commit one or more file fixup commits, and finally tag the
2283 dummy branch.</p>
2284 </div>
2285 <div class="paragraph">
2286 <p>For example since all normal branches are stored under <code>refs/heads/</code>
2287 name the tag fixup branch <code>TAG_FIXUP</code>.  This way it is impossible for
2288 the fixup branch used by the importer to have namespace conflicts
2289 with real branches imported from the source (the name <code>TAG_FIXUP</code>
2290 is not <code>refs/heads/TAG_FIXUP</code>).</p>
2291 </div>
2292 <div class="paragraph">
2293 <p>When committing fixups, consider using <code>merge</code> to connect the
2294 commit(s) which are supplying file revisions to the fixup branch.
2295 Doing so will allow tools such as <em>git blame</em> to track
2296 through the real commit history and properly annotate the source
2297 files.</p>
2298 </div>
2299 <div class="paragraph">
2300 <p>After fast-import terminates the frontend will need to do <code>rm</code> <code>.git/TAG_FIXUP</code>
2301 to remove the dummy branch.</p>
2302 </div>
2303 </div>
2304 <div class="sect2">
2305 <h3 id="_import_now_repack_later">Import Now, Repack Later</h3>
2306 <div class="paragraph">
2307 <p>As soon as fast-import completes the Git repository is completely valid
2308 and ready for use.  Typically this takes only a very short time,
2309 even for considerably large projects (100,000+ commits).</p>
2310 </div>
2311 <div class="paragraph">
2312 <p>However repacking the repository is necessary to improve data
2313 locality and access performance.  It can also take hours on extremely
2314 large projects (especially if -f and a large --window parameter is
2315 used).  Since repacking is safe to run alongside readers and writers,
2316 run the repack in the background and let it finish when it finishes.
2317 There is no reason to wait to explore your new Git project!</p>
2318 </div>
2319 <div class="paragraph">
2320 <p>If you choose to wait for the repack, don&#8217;t try to run benchmarks
2321 or performance tests until repacking is completed.  fast-import outputs
2322 suboptimal packfiles that are simply never seen in real use
2323 situations.</p>
2324 </div>
2325 </div>
2326 <div class="sect2">
2327 <h3 id="_repacking_historical_data">Repacking Historical Data</h3>
2328 <div class="paragraph">
2329 <p>If you are repacking very old imported data (e.g. older than the
2330 last year), consider expending some extra CPU time and supplying
2331 --window=50 (or higher) when you run <em>git repack</em>.
2332 This will take longer, but will also produce a smaller packfile.
2333 You only need to expend the effort once, and everyone using your
2334 project will benefit from the smaller repository.</p>
2335 </div>
2336 </div>
2337 <div class="sect2">
2338 <h3 id="_include_some_progress_messages">Include Some Progress Messages</h3>
2339 <div class="paragraph">
2340 <p>Every once in a while have your frontend emit a <code>progress</code> message
2341 to fast-import.  The contents of the messages are entirely free-form,
2342 so one suggestion would be to output the current month and year
2343 each time the current commit date moves into the next month.
2344 Your users will feel better knowing how much of the data stream
2345 has been processed.</p>
2346 </div>
2347 </div>
2348 </div>
2349 </div>
2350 <div class="sect1">
2351 <h2 id="_packfile_optimization">PACKFILE OPTIMIZATION</h2>
2352 <div class="sectionbody">
2353 <div class="paragraph">
2354 <p>When packing a blob fast-import always attempts to deltify against the last
2355 blob written.  Unless specifically arranged for by the frontend,
2356 this will probably not be a prior version of the same file, so the
2357 generated delta will not be the smallest possible.  The resulting
2358 packfile will be compressed, but will not be optimal.</p>
2359 </div>
2360 <div class="paragraph">
2361 <p>Frontends which have efficient access to all revisions of a
2362 single file (for example reading an RCS/CVS ,v file) can choose
2363 to supply all revisions of that file as a sequence of consecutive
2364 <code>blob</code> commands.  This allows fast-import to deltify the different file
2365 revisions against each other, saving space in the final packfile.
2366 Marks can be used to later identify individual file revisions during
2367 a sequence of <code>commit</code> commands.</p>
2368 </div>
2369 <div class="paragraph">
2370 <p>The packfile(s) created by fast-import do not encourage good disk access
2371 patterns.  This is caused by fast-import writing the data in the order
2372 it is received on standard input, while Git typically organizes
2373 data within packfiles to make the most recent (current tip) data
2374 appear before historical data.  Git also clusters commits together,
2375 speeding up revision traversal through better cache locality.</p>
2376 </div>
2377 <div class="paragraph">
2378 <p>For this reason it is strongly recommended that users repack the
2379 repository with <code>git</code> <code>repack</code> <code>-a</code> <code>-d</code> after fast-import completes, allowing
2380 Git to reorganize the packfiles for faster data access.  If blob
2381 deltas are suboptimal (see above) then also adding the <code>-f</code> option
2382 to force recomputation of all deltas can significantly reduce the
2383 final packfile size (30-50% smaller can be quite typical).</p>
2384 </div>
2385 <div class="paragraph">
2386 <p>Instead of running <code>git</code> <code>repack</code> you can also run <code>git</code> <code>gc</code>
2387 <code>--aggressive</code>, which will also optimize other things after an import
2388 (e.g. pack loose refs). As noted in the "AGGRESSIVE" section in
2389 <a href="git-gc.html">git-gc(1)</a> the <code>--aggressive</code> option will find new deltas with
2390 the <code>-f</code> option to <a href="git-repack.html">git-repack(1)</a>. For the reasons elaborated
2391 on above using <code>--aggressive</code> after a fast-import is one of the few
2392 cases where it&#8217;s known to be worthwhile.</p>
2393 </div>
2394 </div>
2395 </div>
2396 <div class="sect1">
2397 <h2 id="_memory_utilization">MEMORY UTILIZATION</h2>
2398 <div class="sectionbody">
2399 <div class="paragraph">
2400 <p>There are a number of factors which affect how much memory fast-import
2401 requires to perform an import.  Like critical sections of core
2402 Git, fast-import uses its own memory allocators to amortize any overheads
2403 associated with malloc.  In practice fast-import tends to amortize any
2404 malloc overheads to 0, due to its use of large block allocations.</p>
2405 </div>
2406 <div class="sect2">
2407 <h3 id="_per_object">per object</h3>
2408 <div class="paragraph">
2409 <p>fast-import maintains an in-memory structure for every object written in
2410 this execution.  On a 32 bit system the structure is 32 bytes,
2411 on a 64 bit system the structure is 40 bytes (due to the larger
2412 pointer sizes).  Objects in the table are not deallocated until
2413 fast-import terminates.  Importing 2 million objects on a 32 bit system
2414 will require approximately 64 MiB of memory.</p>
2415 </div>
2416 <div class="paragraph">
2417 <p>The object table is actually a hashtable keyed on the object name
2418 (the unique SHA-1).  This storage configuration allows fast-import to reuse
2419 an existing or already written object and avoid writing duplicates
2420 to the output packfile.  Duplicate blobs are surprisingly common
2421 in an import, typically due to branch merges in the source.</p>
2422 </div>
2423 </div>
2424 <div class="sect2">
2425 <h3 id="_per_mark">per mark</h3>
2426 <div class="paragraph">
2427 <p>Marks are stored in a sparse array, using 1 pointer (4 bytes or 8
2428 bytes, depending on pointer size) per mark.  Although the array
2429 is sparse, frontends are still strongly encouraged to use marks
2430 between 1 and n, where n is the total number of marks required for
2431 this import.</p>
2432 </div>
2433 </div>
2434 <div class="sect2">
2435 <h3 id="_per_branch">per branch</h3>
2436 <div class="paragraph">
2437 <p>Branches are classified as active and inactive.  The memory usage
2438 of the two classes is significantly different.</p>
2439 </div>
2440 <div class="paragraph">
2441 <p>Inactive branches are stored in a structure which uses 96 or 120
2442 bytes (32 bit or 64 bit systems, respectively), plus the length of
2443 the branch name (typically under 200 bytes), per branch.  fast-import will
2444 easily handle as many as 10,000 inactive branches in under 2 MiB
2445 of memory.</p>
2446 </div>
2447 <div class="paragraph">
2448 <p>Active branches have the same overhead as inactive branches, but
2449 also contain copies of every tree that has been recently modified on
2450 that branch.  If subtree <code>include</code> has not been modified since the
2451 branch became active, its contents will not be loaded into memory,
2452 but if subtree <code>src</code> has been modified by a commit since the branch
2453 became active, then its contents will be loaded in memory.</p>
2454 </div>
2455 <div class="paragraph">
2456 <p>As active branches store metadata about the files contained on that
2457 branch, their in-memory storage size can grow to a considerable size
2458 (see below).</p>
2459 </div>
2460 <div class="paragraph">
2461 <p>fast-import automatically moves active branches to inactive status based on
2462 a simple least-recently-used algorithm.  The LRU chain is updated on
2463 each <code>commit</code> command.  The maximum number of active branches can be
2464 increased or decreased on the command line with --active-branches=.</p>
2465 </div>
2466 </div>
2467 <div class="sect2">
2468 <h3 id="_per_active_tree">per active tree</h3>
2469 <div class="paragraph">
2470 <p>Trees (aka directories) use just 12 bytes of memory on top of the
2471 memory required for their entries (see &#8220;per active file&#8221; below).
2472 The cost of a tree is virtually 0, as its overhead amortizes out
2473 over the individual file entries.</p>
2474 </div>
2475 </div>
2476 <div class="sect2">
2477 <h3 id="_per_active_file_entry">per active file entry</h3>
2478 <div class="paragraph">
2479 <p>Files (and pointers to subtrees) within active trees require 52 or 64
2480 bytes (32/64 bit platforms) per entry.  To conserve space, file and
2481 tree names are pooled in a common string table, allowing the filename
2482 &#8220;Makefile&#8221; to use just 16 bytes (after including the string header
2483 overhead) no matter how many times it occurs within the project.</p>
2484 </div>
2485 <div class="paragraph">
2486 <p>The active branch LRU, when coupled with the filename string pool
2487 and lazy loading of subtrees, allows fast-import to efficiently import
2488 projects with 2,000+ branches and 45,114+ files in a very limited
2489 memory footprint (less than 2.7 MiB per active branch).</p>
2490 </div>
2491 </div>
2492 </div>
2493 </div>
2494 <div class="sect1">
2495 <h2 id="_signals">SIGNALS</h2>
2496 <div class="sectionbody">
2497 <div class="paragraph">
2498 <p>Sending <strong>SIGUSR1</strong> to the <em>git fast-import</em> process ends the current
2499 packfile early, simulating a <code>checkpoint</code> command.  The impatient
2500 operator can use this facility to peek at the objects and refs from an
2501 import in progress, at the cost of some added running time and worse
2502 compression.</p>
2503 </div>
2504 </div>
2505 </div>
2506 <div class="sect1">
2507 <h2 id="_configuration">CONFIGURATION</h2>
2508 <div class="sectionbody">
2509 <div class="paragraph">
2510 <p>Everything below this line in this section is selectively included
2511 from the <a href="git-config.html">git-config(1)</a> documentation. The content is the same
2512 as what&#8217;s found there:</p>
2513 </div>
2514 <div class="dlist">
2515 <dl>
2516 <dt class="hdlist1">fastimport.unpackLimit</dt>
2517 <dd>
2518 <p>If the number of objects imported by <a href="git-fast-import.html">git-fast-import(1)</a>
2519 is below this limit, then the objects will be unpacked into
2520 loose object files.  However, if the number of imported objects
2521 equals or exceeds this limit, then the pack will be stored as a
2522 pack.  Storing the pack from a fast-import can make the import
2523 operation complete faster, especially on slow filesystems.  If
2524 not set, the value of <code>transfer.unpackLimit</code> is used instead.</p>
2525 </dd>
2526 </dl>
2527 </div>
2528 </div>
2529 </div>
2530 <div class="sect1">
2531 <h2 id="_see_also">SEE ALSO</h2>
2532 <div class="sectionbody">
2533 <div class="paragraph">
2534 <p><a href="git-fast-export.html">git-fast-export(1)</a></p>
2535 </div>
2536 </div>
2537 </div>
2538 <div class="sect1">
2539 <h2 id="_git">GIT</h2>
2540 <div class="sectionbody">
2541 <div class="paragraph">
2542 <p>Part of the <a href="git.html">git(1)</a> suite</p>
2543 </div>
2544 </div>
2545 </div>
2546 </div>
2547 <div id="footer">
2548 <div id="footer-text">
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