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Re^3: capturing command output

by JavaFan (Canon)
on Jan 25, 2012 at 15:54 UTC ( #949923=note: print w/ replies, xml ) Need Help??


in reply to Re^2: capturing command output
in thread capturing command output

If you call via perl backticks then only "hello" is captured, and "world" is still sent to stdout.
I cannot reproduce that.
$ cat foo #!/usr/bin/perl print STDOUT "hello\n"; print STDERR "world\n"; $ cat bar #!/usr/bin/perl use 5.010; my $output = `./foo 2>&1`; say "[[$output]]"; $ chmod +x foo $ chmod +x bar $ ./bar [[world hello ]] $
Or are you suggesting the OP would run a different command in backticks than in his open? Why would he do that?


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Re^4: capturing command output
by chrestomanci (Priest) on Jan 25, 2012 at 16:35 UTC
    Or are you suggesting the OP would run a different command in backticks than in his open? Why would he do that?

    No I am saying that plain backticks, without the 2>&1 shell redirection only captures stdout. If you add the shell redirection then of course you get stderr as well, because you asked the shell to do that for you. (Though as Eliya has demonstrated, it is actually perl intercepting the redirection shell trick and doing it within perl.)

      Hmmm, so, you're saying, it's wrong to use backticks, because if you only put half the command in the backticks, it doesn't work?

      I think that's one of the more stupid arguments one can make. If the OP would remove the 2>&1 from his original solution, it would break in the same way.

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