How to check for existence,executabilituy and return code when executing a shell script from perl

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

Hi, I am modifying a perl script to call a shell script. the shell script usually returns a numeric return code, so i need to check for cases where the file may not be present, may not be executable or may return a non-numeric return code . Ive been toying around with various options and the current code looks like this:

 $proc = \( 0+ `/aa/bb/cc.ksh arg1` ); 
 if (! $proc || $proc !~ /\d/){ ....
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any idea how this should be modified. if you could point me to a concise tutorial also that would help. all the tutorials i find seem to be rather large to dig for a relatively small piece of info.thanks

Comment on How to check for existence,executabilituy and return code when executing a shell script from perl Download Code

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Re: How to check for existence,executabilituy and return code when executing a shell script from perl by kennethk (Abbot) on Feb 11, 2009 at 16:48 UTC
It seems like the more appropriate way of performing your task would be to first test if the file exists, perhaps using the -X functions. They can also check file permissions. Lastly, why in the world are you taking a reference to your return after being forced into numeric context and then testing the value? For what you want to test, you should be calling your backticks as $proc =`/aa/bb/cc.ksh arg1`;. Update: And, to boot, if you want to check your return value for non-decimal characters, your test should be `$proc =~ /\D/` - your regex syntax does not do what you think. Please read perlretut. Update 2:You should also get in the habit of using `or` in place of `\|\|` - otherwise you may get Burned by precedence rules (operator precedence).	[reply] [d/l] [select]
Re: How to check for existence,executabilituy and return code when executing a shell script from perl by ikegami (Patriarch) on Feb 11, 2009 at 16:44 UTC
$?, for starters	[reply]