Capture output from backtick commands using sudo

macron0 has asked for the wisdom of the Perl Monks concerning the following question:

Hello Monks,

How do I get the output from a sudo command using backticks.

If I do this:

$result=`sudo ls -la`;
print "$result\n";
[download]

I get the sudo output:

    sudo: please use single character options
    usage: sudo -K | -L | -V | -h | -k | -l | -v
    usage: sudo [-HPSb] [-p prompt] [-u username|#uid]
                { -e file [...] | -i | -s | <command> }
[download]

If I do this:

$result=`sudo ls -la`;
print "$result\n";
[download]

I get nothing at all.

It seems such a simple question but I cannot find the answer.

So I was wondering if anyone here might know the answer.

I really need to parse the output of some scripts and I also need to use sudo.

Thank you.

Hans de Groot

Comment on Capture output from backtick commands using sudo Select or Download Code

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Re: Capture output from backtick commands using sudo by afoken (Chancellor) on Apr 04, 2010 at 12:06 UTC
Your example works for me, and I fail to see a difference between $result=`sudo ls -la`; print "$result\n"; [download] and $result=`sudo ls -la`; print "$result\n"; [download] . The first error message looks like you have placed the ls options before the ls command. Show us the real code that fails, copied and pasted into <code> tags. Alexander -- Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)	[reply] [d/l] [select]
Re: Capture output from backtick commands using sudo by ww (Archbishop) on Apr 04, 2010 at 12:34 UTC
Please read the Monastery's documentation -- particularly that on the page at which you entered the above. Use para tags (<p>...</p>) for paragraphs, and <c>...</c> to surround code and data. But, don't use <pre> tags. See Markup in the Monastery, Perl Monks Approved HTML tags and Writeup Formatting Tips.	[reply]
Re^2: Capture output from backtick commands using sudo by Anonymous Monk on Oct 03, 2013 at 15:55 UTC
Hi, I stumbled across the same issue as you. In fact, since sudo will return: 'Upon successful execution of a program, the exit status from sudo will simply be the exit status of the program that was executed.' - you will not the the result of the 'ls'. In a specific case, what I wished for was the output of the executed program ('ls', for you). Did you find an answer for this? I'd really prefer not to use any temp files. Thanks! Norbert	[reply]
Re^3: Capture output from backtick commands using sudo by Happy-the-monk (Canon) on Oct 03, 2013 at 16:28 UTC
Huh? Give perl -E 'say `sudo "/bin/ls"`' a try. The exit status is not the STDOUT of the programme, but it's "return code". Like: did the command succeed? Cheers, Sören Créateur des bugs mobiles - let loose once, run everywhere. (hooked on the Perl Programming language)	[reply] [d/l]