FAQ: Why doesn't open() return an error when a pipe open fails?

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This message is one of several periodic postings to comp.lang.perl.misc
intended to make it easier for perl programmers to find answers to
common questions. The core of this message represents an excerpt
from the documentation provided with Perl.


8.26: Why doesn't open() return an error when a pipe open fails?

    If the second argument to a piped open() contains shell metacharacters,
    perl fork()s, then exec()s a shell to decode the metacharacters and
    eventually run the desired program. If the program couldn't be run, it's
    the shell that gets the message, not Perl. All your Perl program can
    find out is whether the shell itself could be successfully started. You
    can still capture the shell's STDERR and check it for error messages.
    See the section on "How can I capture STDERR from an external command?"
    elsewhere in this document, or use the IPC::Open3 module.

    If there are no shell metacharacters in the argument of open(), Perl
    runs the command directly, without using the shell, and can correctly
    report whether the command started.


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