Two copies of one input stream
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From: John Kelly on 3 Jul 2010 01:57 Two copies of one input stream -- I think I did this before but I forgot how. So I did it again. There's probably a better way, but this works: The "cat >Stream " commands are just a sample; you can replace them with whatever you want to do with each stream. #!/bin/bash exit_ () { set +u [[ $td == /tmp/[^/]* ]] && rm -rf $td || : } trap exit_ EXIT td=`mktemp -d` mkfifo "$td/f1" exec 3<>"$td/f1" exec 4> "$td/f1" exec 3< "$td/f1" ( exec <&3- 4>&- cat >Stream1 ) & mkfifo "$td/f2" exec 3<>"$td/f2" exec 5> "$td/f2" exec 3< "$td/f2" ( exec <&3- 5>&- cat >Stream2 ) & exec 3>&1 # Keep a copy of STDOUT so it can be restored later if needed tee /dev/fd/4 >/dev/fd/5 exec 4>&- 5>&- wait $! -- Web mail, POP3, and SMTP http://www.beewyz.com/freeaccounts.php
From: John Kelly on 3 Jul 2010 03:19
On Sat, 03 Jul 2010 05:57:54 +0000, John Kelly <jak(a)isp2dial.com> wrote: >Two copies of one input stream -- I think I did this before but I forgot >how. So I did it again. There's probably a better way Seems there is -- process subsitution in bash: #!/bin/bash tee >(cat >Stream1) >(cat >Stream2) >/dev/null >The "cat >Stream " commands are just a sample; you can replace them with >whatever you want to do with each stream. > > > >#!/bin/bash > >exit_ () { > set +u > [[ $td == /tmp/[^/]* ]] && rm -rf $td || : >} >trap exit_ EXIT > >td=`mktemp -d` > >mkfifo "$td/f1" >exec 3<>"$td/f1" >exec 4> "$td/f1" >exec 3< "$td/f1" >( > exec <&3- 4>&- > cat >Stream1 >) & > >mkfifo "$td/f2" >exec 3<>"$td/f2" >exec 5> "$td/f2" >exec 3< "$td/f2" >( > exec <&3- 5>&- > cat >Stream2 >) & > >exec 3>&1 # Keep a copy of STDOUT so it can be restored later if needed > >tee /dev/fd/4 >/dev/fd/5 > >exec 4>&- 5>&- > >wait $! Same result, but the hard way. Oh well, it was good exercise with FIFOs and redirection. After posting this, I noticed a small anomaly with the "wait $!" and /dev/fd/4. It works OK as is, but two minor changes would tighten it up. -- Web mail, POP3, and SMTP http://www.beewyz.com/freeaccounts.php |