user-tools/substenv

   1 #!/usr/bin/env perl
   2
   3 =pod
   4
   5 =head1 NAME
   6
   7 substenv - Substitute environment variables in parameters and run the resulting command
   8
   9 =head1 SYNOPSIS
  10
  11 substenv I<COMMAND> [I<ARGS>]
  12
  13 =head1 DESCRIPTION
  14
  15 Replace all occurrances of C<$NAME> in I<COMMAND> and I<ARGS> to the I<NAME> environment
  16 variable's value, then run I<COMMAND>.
  17
  18 =head1 EXAMPLE
  19
  20  system('substenv', 'ls', '$HOME/.config')
  21
  22 runs:
  23
  24  execve('ls', ['ls', '/home/jdoe/.config'])
  25
  26 =head1 NOTES
  27
  28 Does not support full shell-like variable interpolation.
  29 Use a real shell for it.
  30
  31 =head1 RATIONALE
  32
  33 Sometimes you don't want a shell to be in the picture when composing commands,
  34 yet need to weave some environment variable into it.
  35
  36 =head1 SEE ALSO
  37
  38 envsubst(1) from gettext-base package
  39
  40 =cut
  41
  42
  43 @run_cmd = ();
  44
  45 for my $arg (@ARGV)
  46 {
  47         $arg =~ s/\$([A-Z0-9_]+)/$ENV{$1}/g;
  48         push @run_cmd, $arg;
  49 }
  50
  51 exec {$run_cmd[0]} @run_cmd;
  52 exit 127;