user-tools/redirexec

   1 #!/usr/bin/env perl
   2
   3 use POSIX qw/dup2/;
   4
   5 $0 =~ s/.*\/([^\/]+)$/$1/;
   6
   7 %perlopenmode = (
   8         'r' => {symbol => '<', word => 'read'},
   9         'c' => {symbol => '>', word => 'create/clobber'},
  10         'rw' => {symbol => '+<', word => 'read/write'},
  11         'a' => {symbol => '>>', word => 'append'},
  12 );
  13
  14 @redirs = ();
  15
  16 while(@ARGV)
  17 {
  18         my $fdspec = shift @ARGV;
  19         if($fdspec eq '--') { last; }
  20         if($fdspec =~ /^(?'fd'\d+|std(in|out|err)):(?'dest'-|(?'mode'r|c|rw|a):(file:(?'path'.+)|fd:(?'fileno'\d+|std(in|out|err))))$/)
  21         {
  22                 my ($fd, $dest, $mode, $path, $fileno) = ($+{'fd'}, $+{'dest'}, $+{'mode'}, $+{'path'}, $+{'fileno'});
  23                 $fd = 0 if $fd eq 'stdin';
  24                 $fd = 1 if $fd eq 'stdout';
  25                 $fd = 2 if $fd eq 'stderr';
  26                 $fileno = 0 if $fileno eq 'stdin';
  27                 $fileno = 1 if $fileno eq 'stdout';
  28                 $fileno = 2 if $fileno eq 'stderr';
  29                 if($dest eq '-')
  30                 {
  31                         $mode = 'rw';
  32                         $path = '/dev/null';
  33                 }
  34                 push @redirs, {
  35                         fd => $fd,
  36                         mode => $perlopenmode{$mode}->{'symbol'} . (defined $fileno ? '&=' : ''),
  37                         modename => $perlopenmode{$mode}->{'word'},
  38                         file => defined $fileno ? $fileno : $path,
  39                 };
  40         }
  41         else
  42         {
  43                 warn "invalid redirect specification: $fdspec\n";
  44                 pod2usage(-exitval=>2, -verbose=>99);
  45         }
  46 }
  47
  48 @command = @ARGV;
  49
  50 for my $redir (@redirs)
  51 {
  52         open $fh, $redir->{'mode'}, $redir->{'file'} or die "$0: can not open ($redir->{'modename'}) $redir->{'file'}: $!\n";
  53         dup2(fileno $fh, $redir->{'fd'}) or die "$0: can not duplicate fd of $redir->{'file'}: $!\n";
  54 }
  55
  56 exec {$command[0]} @command;
  57
  58
  59 __END__
  60
  61
  62 =pod
  63
  64 =head1 NAME
  65
  66 redirexec - Execute a command with some file descriptiors redirected.
  67
  68 =head1 SYNOPSIS
  69
  70 redirexec [I<FILENO>:I<MODE>:file:I<PATH>] -- I<COMMAND> I<ARGS>
  71
  72 redirexec [I<FILENO>:I<MODE>:fd:I<FD>] -- I<COMMAND> I<ARGS>
  73
  74 redirexec [I<FILENO>:-] -- I<COMMAND> I<ARGS>
  75
  76 =head1 DESCRIPTION
  77
  78 Setup redirections before executing I<COMMAND>.
  79 You can setup the same type of file and file descriptor redirections as in shell.
  80
  81 I<FILENO> and I<FD> are file descriptor integers or literal "stdin", "stdout", or "stderr".
  82
  83 I<MODE> is one of:
  84
  85 =over 4
  86
  87 =item r
  88
  89 read
  90
  91 =item c
  92
  93 create/clobber
  94
  95 =item rw
  96
  97 read and write
  98
  99 =item a
 100
 101 append
 102
 103 =back
 104
 105 =head1 EXAMPLES
 106
 107   +-----------------+--------------------------+
 108   | shell syntax    | redirexec(1) equivalents |
 109   +=================+==========================+
 110   | > output.txt    | stdout:c:file:output.txt |
 111   |                 | 1:c:file:output.txt      |
 112   +-----------------+--------------------------+
 113   | 2>&1            | stderr:c:fd:stdout       |
 114   |                 | 2:c:fd:1                 |
 115   +-----------------+--------------------------+
 116   | </dev/null      | 0:r:file:/dev/null       |
 117   |                 | 0:-                      |
 118   +-----------------+--------------------------+
 119   | >/dev/null 2>&1 | 1:- 2:-                  |
 120   +-----------------+--------------------------+
 121
 122
 123 =head1 SEE ALSO
 124
 125 redirfd by execlineb(1)
 126
 127 =cut