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sending the STDOUT and the STDERR to programs in the shell

Posted on 2007-03-29
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Last Modified: 2013-12-26
Sending the STDOUT and the STDERR to programs.

I can do:
 perl -e 'print "aaa\n"; warn "bbb\n"' | perl -ne 'print "   $_"'
 perl -e 'print "aaa\n"; warn "bbb\n"' 2| perl -ne 'print "** $_"'

but I can't do bout:

 perl -e 'print "aaa\n"; warn "bbb\n"' | perl -ne 'print "   $_"'  2| perl -ne 'print "** $_"'


Notice that the important part of the question is:
How to use the | and 2| in the some command line?
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Question by:oleber
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6 Comments
 
LVL 143

Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 18815885
0
 
LVL 10

Author Comment

by:oleber
ID: 18817225
This isn't a perl question.
the question is:

How to use the | and 2| in the some command line?

Or better, I need the STDOUT to go to one process and the STDERR to another. The perl in this example is just because I'm used to use it, but I can't do it in this project. Just C, the real old C.
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LVL 143

Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 18817502
I see.
in the shell as such, you need to use the 2&>1 to get the stderr redirected to the stdout.

as I don't use unix alot, I am not sure where to put that:

 perl -e 'print "aaa\n"; warn "bbb\n"' 2&>1 | perl -ne 'print "   $_"'

 perl -e 'print "aaa\n"; warn "bbb\n"' | perl -ne 'print "   $_"' 2&>1
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LVL 84

Expert Comment

by:ozo
ID: 18827893
(perl -e 'print "aaa\n"; warn "bbb\n"' | perl -ne 'print "   $_"; ') 3>&1 1>&2 2>&3 3>&-  | perl -ne 'print "** $_"'
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LVL 10

Author Comment

by:oleber
ID: 18827954
there is a order problem

The command:
(perl -e 'print "aaa\n"; sleep(1); warn "bbb\n"; sleep(1); warn "ccc\n"' | perl -ne 'print "   $_"; ') 3>&1 1>&2 2>&3 3>&-  | perl -ne 'print "** $_"'

is printing:
** bbb
** ccc
   aaa

in my cygwin.

so it isn't a good solution.

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LVL 84

Accepted Solution

by:
ozo earned 125 total points
ID: 18829162
(perl -e '$|=1; print "aaa\n"; sleep(1); warn "bbb\n"; sleep(1); warn "ccc\n"' | perl -ne 'print "   $_"; ') 3>&1 1>&2 2>&3 3>&-  | perl -ne 'print "** $_"'
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