Unsuccessfully passing arguments to a bash command

zapatafa has asked for the wisdom of the Perl Monks concerning the following question:

I'm trying to pass arguments to a function defined in .bashrc. I don't have any control over the contents of the .bashrc.

For the sake of argument: In .bashrc there is a function defined along the lines of:

function untouchable {
    perl ./untouchable.pl $*
}
export -f untouchable
[download]

where the script untouchable.pl is also not something I have any control over:

#!/usr/bin/perl
use strict 'vars';
my @people = @ARGV;
print "Staring...\n";
foreach my $person ( @people ){
   print "Hello $person\n";
 }
print "done!\n";
[download]

I'm trying to make a system call to this function from within a perl script as follows:

#!/usr/bin/perl
system ("bash -ic untouchable john mike bill");
[download]

But my arguments john mike bill are completely lost.

I know I could make a call directly to the untouchable.pl in this particular scenario here. But, I'm actually interested in how to make an interactive call to the bash command.

If I run untouchable from the command line, it works as expected. How do I write a perl script to make a system call to untouchable and get this call to also pass my arguments along?

Comment on Unsuccessfully passing arguments to a bash command Select or Download Code

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Re: Unsuccessfully passing arguments to a bash command by ikegami (Patriarch) on Jun 16, 2013 at 05:02 UTC
`$` reflects the args passed to the function, but you didn't pass any! You merely passed some to `bash` as you executed the bash command `untouchable`. You want to execute the bash command `untouchable john mike bill`, which you can do using `system(q{bash -ic 'untouchable john mike bill'});` [download] or better yet, `system('bash', '-ic', 'untouchable john mike bill');` [download] The latter launches `bash` directly instead of launching a `sh` to launch `bash`. If the names are variable, you want: `use String::ShellQuote qw( shell_quote ); system('bash', '-ic', shell_quote('untouchable', @names));` [download] or `system('bash', '-ic', 'untouchable "$@"', '-', @names);` [download] If I run untouchable from the command line, it works as expected.* But running the command you passed to `system` wouldn't have.	[reply] [d/l] [select]
Re: Unsuccessfully passing arguments to a bash command by Happy-the-monk (Canon) on Jun 15, 2013 at 21:17 UTC
this does it for me: `perl -e'print qx(bash -ic "untouchable john mike bill");'` So it was about the right quoting to protect it from the shell. Cheers, Sören (hooked on the Perl Programming language)	[reply] [d/l]
Re^2: Unsuccessfully passing arguments to a bash command by zapatafa (Initiate) on Jun 15, 2013 at 21:48 UTC
Works perfectly. Thank you.	[reply]
Re: Unsuccessfully passing arguments to a bash command by Happy-the-monk (Canon) on Jun 15, 2013 at 20:27 UTC
I am a bit wary about the calling of a shell/bash function and possible gotchas, ...but I also think you should try passing parameters to system as a list or an array. See if that gets you there. Cheers, Sören (hooked on the Perl Programming language)	[reply]
Re: Unsuccessfully passing arguments to a bash command by choroba (Cardinal) on Jun 16, 2013 at 09:00 UTC
Bash comment: It is better to use `perl ./untouchalbe.pl "$@"` [download] That way, you can correctly process arguments containing whitespace. لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l]
Re^2: Unsuccessfully passing arguments to a bash command by ikegami (Patriarch) on Jun 16, 2013 at 15:51 UTC
~~`"$*"` in this case.~~	[reply] [d/l]
Re: Unsuccessfully passing arguments to a bash command by flexvault (Monsignor) on Jun 15, 2013 at 20:14 UTC
Welcome zapatafa, Most times when you call a shell, the problem is in the special characters of Perl and of the shell. Try doing this: `my $cmd = qq\|[Path]bash -ic ...\|; print "$cmd\n"; system($cmd);` [download] Then look for any differences from your command line call. Replace Path with the full path name to get to 'bash'. Update: Happy-the-monk pointed out my error, thanks. Regards...Ed "Well done is better than well said." - Benjamin Franklin	[reply] [d/l]
Re^2: Unsuccessfully passing arguments to a bash command by zapatafa (Initiate) on Jun 15, 2013 at 20:22 UTC
I've tried this. But even if I write `#!/usr/bin/perl my $cmd = qq\|/bin/bash -ic untouchable john mike bill\|; print $cmd; system ($cmd);` [download] The output is `/bin/bash -ic untouchable john mike billStarting... done!` [download] Somehow the arguments `john mike bill` are getting lost.	[reply] [d/l] [select]
Re^3: Unsuccessfully passing arguments to a bash command by Anonymous Monk on Jun 15, 2013 at 20:59 UTC
Where john mike bill are what?	[reply]
Re: Unsuccessfully passing arguments to a bash command by poj (Abbot) on Jun 15, 2013 at 21:24 UTC
Try ; `#!/usr/bin/perl my @args = ("bash","-ic","untouchable john mike bill"); system(@args);` [download] poj	[reply] [d/l]