linux - Executing a bash script from a Perl program -

i'm trying write perl program execute bash script. perl script looks this

#!/usr/bin/perl  use diagnostics; use warnings;  require 'userlib.pl'; use cgi qw(:standard);   readparse();  $q = new cgi; $dir = $q->param('x'); $s = $q->param('y');  ui_print_header(undef, $text{'edit_title'}.$dir, "");  print  $dir."<br>"; print  $s."<br>"; print "under construction <br>";  use cwd; $pwd = cwd(); $directory = "/logs/".$dir."/logmanager/".$s; $command = $pwd."/script ".$directory."/".$s.".tar";  print $command."<br>"; print $pwd."<br>";  chdir($directory); $pwd1 = cwd(); print $pwd1."<br>";  system($command, $directory) or die "cannot open dir: $!"; 

the script fail following error:

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can't exec "/usr/libexec/webmin/foobar/script     /path/filename.tar": no such file or directory @ /usr/libexec/webmin/foobar/program.cgi line 23 (#3) (w exec) system(), exec(), or piped open call not execute named program indicated reason.  typical reasons include: permissions wrong on file, file wasn't found in $env{path}, executable in question compiled architecture, or #! line in script points interpreter can't run similar reasons.  (or maybe system doesn't support #!                  @ all.)         

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i've checked permissions correct, tar file i'm passing bash script exists, , tried command line run same command i'm trying run perl script ( /usr/libexec/webmin/foobar/script /path/filename.tar ) , works properly.

in perl, calling system 1 argument (in scalar context) , calling several scalar arguments (in list context) different things.

in scalar context, calling

system($command) 

will start external shell , execute $command in it. if string in $command has arguments, passed call, too. example

$command="ls /"; system($commmand); 

will evaluate to

sh -c "ls /" 

where shell given entire string, i.e. command arguments. also, $command run normal environment variables set. can security issue, see here , here few examples why.

on other hand, if call system array (in list context), perl not call shell , give $command argument, rather try execute first element of array directly , give other arguments parameters. so

$command = "ls"; $directory = "/"; system($command, $directory); 

will call ls directly, without spawning shell in between.

back question: code says

my $command = $pwd."/script ".$directory."/".$s.".tar"; system($command, $directory) or die "cannot open dir: $!"; 

note $command here /path/to/script /path/to/foo.tar, argument being part of string. if call in scalar context

system($command) 

all work fine, because

sh -c "/path/to/script /path/to/foo.tar" 

will execute script foo.tar argument. if call in list context, try locate executable named /path/to/script /path/to/foo.tar, , fail.