usr/src/lib/libcmd/common/head.c

   1 /***********************************************************************
   2 *                                                                      *
   3 *               This software is part of the ast package               *
   4 *          Copyright (c) 1992-2010 AT&T Intellectual Property          *
   5 *                      and is licensed under the                       *
   6 *                  Common Public License, Version 1.0                  *
   7 *                    by AT&T Intellectual Property                     *
   8 *                                                                      *
   9 *                A copy of the License is available at                 *
  10 *            http://www.opensource.org/licenses/cpl1.0.txt             *
  11 *         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
  12 *                                                                      *
  13 *              Information and Software Systems Research               *
  14 *                            AT&T Research                             *
  15 *                           Florham Park NJ                            *
  16 *                                                                      *
  17 *                 Glenn Fowler <gsf@research.att.com>                  *
  18 *                  David Korn <dgk@research.att.com>                   *
  19 *                                                                      *
  20 ***********************************************************************/
  21 #pragma prototyped
  22 /*
  23  * David Korn
  24  * AT&T Bell Laboratories
  25  *
  26  * output the beginning portion of one or more files
  27  */
  28
  29 static const char usage[] =
  30 "[-n?\n@(#)$Id: head (AT&T Research) 2006-09-27 $\n]"
  31 USAGE_LICENSE
  32 "[+NAME?head - output beginning portion of one or more files ]"
  33 "[+DESCRIPTION?\bhead\b copies one or more input files to standard "
  34     "output stopping at a designated point for each file or to the end of "
  35     "the file whichever comes first. Copying ends at the point indicated by "
  36     "the options. By default a header of the form \b==> \b\afilename\a\b "
  37     "<==\b is output before all but the first file but this can be changed "
  38     "with the \b-q\b and \b-v\b options.]"
  39 "[+?If no \afile\a is given, or if the \afile\a is \b-\b, \bhead\b "
  40     "copies from standard input starting at the current location.]"
  41 "[+?The option argument for \b-c\b, and \b-s\b can optionally be "
  42     "followed by one of the following characters to specify a different unit "
  43     "other than a single byte:]"
  44     "{"
  45         "[+b?512 bytes.]"
  46         "[+k?1-killobyte.]"
  47         "[+m?1-megabyte.]"
  48     "}"
  49 "[+?For backwards compatibility, \b-\b\anumber\a is equivalent to \b-n\b "
  50     "\anumber\a.]"
  51 "[n:lines?Copy \alines\a lines from each file.]#[lines:=10]"
  52 "[c:bytes?Copy \achars\a bytes from each file.]#[chars]"
  53 "[q:quiet|silent?Never ouput filename headers.]"
  54 "[s:skip?Skip \askip\a characters or lines from each file before "
  55     "copying.]#[skip]"
  56 "[v:verbose?Always ouput filename headers.]"
  57     "\n\n"
  58 "[ file ... ]"
  59     "\n\n"
  60 "[+EXIT STATUS?]"
  61     "{"
  62         "[+0?All files copied successfully.]"
  63         "[+>0?One or more files did not copy.]"
  64     "}"
  65 "[+SEE ALSO?\bcat\b(1), \btail\b(1)]"
  66 ;
  67
  68 #include <cmd.h>
  69
  70 int
  71 b_head(int argc, register char** argv, void* context)
  72 {
  73         static const char       header_fmt[] = "\n==> %s <==\n";
  74
  75         register Sfio_t*        fp;
  76         register char*          cp;
  77         register off_t          keep = 10;
  78         register off_t          skip = 0;
  79         register int            delim = '\n';
  80         int                     header = 1;
  81         char*                   format = (char*)header_fmt+1;
  82
  83         cmdinit(argc, argv, context, ERROR_CATALOG, 0);
  84         for (;;)
  85         {
  86                 switch (optget(argv, usage))
  87                 {
  88                 case 'c':
  89                         delim = -1;
  90                         /*FALLTHROUGH*/
  91                 case 'n':
  92                         if (opt_info.offset && argv[opt_info.index][opt_info.offset] == 'c')
  93                         {
  94                                 delim = -1;
  95                                 opt_info.offset++;
  96                         }
  97                         if ((keep = opt_info.number) <=0)
  98                                 error(2, "%s: %I*d: positive numeric option argument expected", opt_info.name, sizeof(keep), keep);
  99                         continue;
 100                 case 'q':
 101                         header = argc;
 102                         continue;
 103                 case 'v':
 104                         header = 0;
 105                         continue;
 106                 case 's':
 107                         skip = opt_info.number;
 108                         continue;
 109                 case '?':
 110                         error(ERROR_usage(2), "%s", opt_info.arg);
 111                         continue;
 112                 case ':':
 113                         error(2, "%s", opt_info.arg);
 114                         continue;
 115                 }
 116                 break;
 117         }
 118         argv += opt_info.index;
 119         argc -= opt_info.index;
 120         if (error_info.errors)
 121                 error(ERROR_usage(2), "%s", optusage(NiL));
 122         if (cp = *argv)
 123                 argv++;
 124         do
 125         {
 126                 if (!cp || streq(cp, "-"))
 127                 {
 128                         cp = "/dev/stdin";
 129                         fp = sfstdin;
 130                         sfset(fp, SF_SHARE, 1);
 131                 }
 132                 else if (!(fp = sfopen(NiL, cp, "r")))
 133                 {
 134                         error(ERROR_system(0), "%s: cannot open", cp);
 135                         continue;
 136                 }
 137                 if (argc > header)
 138                         sfprintf(sfstdout, format, cp);
 139                 format = (char*)header_fmt;
 140                 if (skip > 0)
 141                         sfmove(fp, NiL, skip, delim);
 142                 if (sfmove(fp, sfstdout, keep, delim) < 0 && errno != EPIPE)
 143                         error(ERROR_system(0), "%s: read error", cp);
 144                 if (fp != sfstdin)
 145                         sfclose(fp);
 146         } while (cp = *argv++);
 147         if (sfsync(sfstdout))
 148                 error(ERROR_system(0), "write error");
 149         return error_info.errors != 0;
 150 }