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Top Forums Shell Programming and Scripting Perl: How to check if there is something being piped in Post 302721175 by zaxxon on Thursday 25th of October 2012 08:19:16 AM
Old 10-25-2012
Perl: How to check if there is something being piped in

Hi,

I am somewhat new to Perl and currently checking it out. I have a problem testing, if there is nothing being piped in to that script.

I am reading input from STDIN this way:
Code:
while( defined($line = <STDIN>) ) {
        chomp($line);
        if( $line =~ m/($ARGV[0])/g ) {
                $count++;
        }
}

In other words, my script works fine but when there is nothing being piped in, it just stops and waits for input.
I have tried several things I found on different pages but I wasn't able to get it to work.
Is there a simple way to check and avoid this?

Thanks in forward!

Last edited by zaxxon; 10-25-2012 at 09:25 AM.. Reason: spelling
 

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ATF-SH(1)						    BSD General Commands Manual 						 ATF-SH(1)

NAME
atf-sh [-s shell] -- interpreter for shell-based test programs SYNOPSIS
atf-sh script DESCRIPTION
atf-sh is an interpreter that runs the test program given in script after loading the atf-sh(3) library. atf-sh is not a real interpreter though: it is just a wrapper around the system-wide shell defined by ATF_SHELL. atf-sh executes the inter- preter, loads the atf-sh(3) library and then runs the script. You must consider atf-sh to be a POSIX shell by default and thus should not use any non-standard extensions. The following options are available: -s shell Specifies the shell to use instead of the value provided by ATF_SHELL. ENVIRONMENT
ATF_LIBEXECDIR Overrides the builtin directory where atf-sh is located. Should not be overridden other than for testing purposes. ATF_PKGDATADIR Overrides the builtin directory where libatf-sh.subr is located. Should not be overridden other than for testing purposes. ATF_SHELL Path to the system shell to be used in the generated scripts. Scripts must not rely on this variable being set to select a specific interpreter. EXAMPLES
Scripts using atf-sh(3) should start with: #! /usr/bin/env atf-sh Alternatively, if you want to explicitly choose a shell interpreter, you cannot rely on env(1) to find atf-sh. Instead, you have to hardcode the path to atf-sh in the script and then use the -s option afterwards as a single parameter: #! /path/to/bin/atf-sh -s/bin/bash ENVIRONMENT
ATF_SHELL Path to the system shell to be used in the generated scripts. SEE ALSO
atf-sh(3) BSD
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