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Capturing STDERR Output

Posted on 1999-01-21
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Last Modified: 2008-03-10
I have a process that return text using STDERR.
I need to run something like:
@out=`process command`;
To get the output, but this gets only STDOUT.
How can I get the STDERR like that in an Easy way?
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Question by:eofek
2 Comments
 
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Expert Comment

by:thoellri
ID: 1210227
From "perldoc perlfaq8" :

     With any of these, you can change file descriptors before
     the call:

         open(STDOUT, ">logfile");
         system("ls");

     or you can use Bourne shell file-descriptor redirection:

         $output = `$cmd 2>some_file`;
         open (PIPE, "cmd 2>some_file |");

     You can also use file-descriptor redirection to make STDERR
     a duplicate of STDOUT:

         $output = `$cmd 2>&1`;
         open (PIPE, "cmd 2>&1 |");

Hope this helps
   Tobias

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Accepted Solution

by:
meyoz earned 100 total points
ID: 1210228
Use this (I've checked it myself - it's working):

$pipename="pipename";
system("mkfifo -m 600 $pipename"); || die("Cannot make fifo: $!\n");
if (!fork()) {
  close(STDOUT);
  open(STDOUT,">$pipename");
  close(STDERR);
  open(STDERR,">$pipename");
  system("cmd"); # place your command here
  exit(0);
} else {
  open(CATCH,"<$pipename");
# now you have STD(OUT,ERR) of cmd in CATCH
# or you can do so:
#  @out=`cat $pipename`
}
unlink("$pipename");

You will get mixed STDOUT and STDERR
I think it's clear how to capture STDOUT and STDERR separately :)

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