in reply to Re: Confusion with finding strings in command output
in thread Confusion with finding strings in command output

It is a two-step process: first a shell command run under qx to retrieve the output (including STDERR thanks to the shell redirection), and then an analysis of the output.

Replies are listed 'Best First'.
Re^3: Confusion with finding strings in command output
by Anonymous Monk on Aug 30, 2014 at 20:07 UTC

    I know that standard error is being redirected. Do look again at OP's code (simplified)... 

    my $SUCCESS = 0;
my %Error   = ( q[No such file or directory] => 1 );

my @out = qx { command here 2>&1 };
my $rc = $?;

if ( $rc == $SUCCESS )
{
  #  As I wrote earlier, if command was sucessful, then why would
  #  there be no-file-found error (under normal conditions)? Else,
  #  exit code cannot be trusted.
  ... = grep { $Error{$_} } @out;
  ...
}
...

    [download]
[reply]
[d/l]
      Hmm, there is a misunderstanding. My point is that we have no idea about what output this line: 
      my @out = qx { command here 2>&1 };

      [download]
      produces, because we don't know what command here is. As an example, if "command here" if a shell find . -name ... -print ... command, it might very well produce successful lines as well as error lines.
[reply]
[d/l]
[select]

In Section Seekers of Perl Wisdom