CODEWITHSUNDEEP
perl
user2933738
user2933738

Reputation: 75

Perl backtick behaves differently than console commands

So, I'm writing a Perl script which at one point needs to process the output of another script. I tried to do this by calling the script in backticks:

 my @output = `scriptName`;

I have tested the script I want to call in backticks, and it works just fine--in the same shell I'm calling my script in, even. But when I call it as part of the script, it produces no output. The variable is left empty.

I've tried executing the command with system(), but there is still no output. I have no idea why. However, the specific arguments I'm passing into the script have caused me problems before until I fixed my PATH variable. Does calling a script through a Perl script result in different environment variables somehow?

Edit: Okay, here's a potential issue. I tried using backticks and system() to print out my PATH variable, and both of them are coming up blank. Is my Perl script unable to use my PATH for some reason?

Upvotes: 1

Views: 1352

Answers (2)

Jarmund
Jarmund

Reputation: 3205

The most common cause of problems such as these, is difference in relative paths. I have a tendency of using absolute paths for that reason.

In addition, it sounds to me like your subscript might be printing to STDERR and not STDOUT. Backticks only capture STDOUT, so you need to do a redirect with the help of 2>&1

my @output = `scriptName 2>&1`;

NB: The redirect doesn't work with all shells (I believe it was tcsh that didn't support it back when i had a similar problem). Bash takes the redirect just fine.

Upvotes: 1

Sobrique
Sobrique

Reputation: 53478

Environment isn't your problem, unless you're explicitly adjusting it within perl, prior to calling your script. My suggestion would be - double check permissions on your script, and check relative paths. I note you don't have ./scriptName - so if it's not in your path, perl won't be able to find it either.

Upvotes: 0

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