Listing 1 runmany.pl

#!/usr/bin/perl

$Version = 'runmany v1.5 - last change 2001-08-24 11:37:07-04';

use Getopt::Std;
&getopts("dv") || &Usage;

&Usage if $#ARGV != 1; # sanity check on args present and accounted for
$proc = shift(@ARGV);
$limit = shift(@ARGV);

print STDERR "Cmd: \"$proc\"\nNum: $limit\n" if $opt_v || $opt_d;

while (<>) {
         chop;
         unless (fork()) {
                  if ($proc =~ m/%s/) {
                           ($cmd = $proc) =~ s/%s/$_/g;
                  } else {
                           $cmd = "${proc} $_";
                  }                  
                  exec $cmd;
         }
         ++$started;
         $running = $started - $finished;
         print STDERR "$started $finished\n" if $opt_d;
         if ($limit <= $running) {
                  wait;
                  ++$finished;
         }
}

# wait for last children and exit clean
until ($finished == $started) {
         print STDERR "Final wait: $started  $finished\n" if $opt_d;
         wait;
         ++$finished;
}
exit 0;

sub Usage
{
         print "\n$Version\n\n"
         . "Usage:\n"
         . "  runmany [options] <cmd string> <count>\n"
         . "\n"
         . "lines are read from stdin, and the values read are used to replace\n"
         . "any instances of \"%s\" in the <cmd string>. Copies of the modified\n"
         . "command are started until <count> copies are running, then a new copy\n"
         . "is started every time a command process ends.\n"
         . "\n"
         . "This is useful when more than one item may be processed at a time, but\n"
         . "processing all possible commands at once could / would overload the system.\n"
         . "\n"
         . "Options:\n"
         . "  -v    Verbose, output the command and count when starting\n"
         . "  -d    Debug. Output a bunch of data while running.\n"
         . "\n"
         . "Example:\n"
         . "  ls | grep '\.o\$' | runmany \"gzip -8v %s\" 3\n"
         . "\n"
         . "would compress three files at a time (presumable on a system with at\n"
         . "least that many processors.\n"
         . "\n"
         . "Author: Bill Davidsen <davidsen\@tmr.com>\n"
         . "\n";

         exit 1;
}