log a command to console and to 2 files separately stdout and stderr

command > >(tee stdout.log) 2> >(tee stderr.log >&2)

9
By: bandie91
2011-10-20 15:08:33

These Might Interest You

  • Useful to recover a output(stdout and stderr) "disown"ed or "nohup"ep process of other instance of ssh. With the others options the stdout / stderr is intercepted, but only the first n chars. This way we can recover ALL text of stdout or stderr Show Sample Output


    3
    strace -e write=1,2 -p $PID 2>&1 | sed -un "/^ |/p" | sed -ue "s/^.\{9\}\(.\{50\}\).\+/\1/g" -e 's/ //g' | xxd -r -p
    glaudiston · 2010-10-06 19:37:39 1
  • When you run an X program from a terminal you can see any errors. But when it's run from another X program (eg from a menu item, from your fluxbox 'keys' file etc) it might just die and you see nothing (except perhaps in .xsession-errors). Instead, launch it via this command and you'll see the termination status, stderr and stdout. eg: "xlaunch firefox" or "xlaunch 'echo stdout; echo stderr >&2; false'": 'echo stdout; echo stderr >&2; false' failed with error 1 STDERR: stderr STDOUT: stdout


    1
    xlaunch(){ T=/tmp/$$;sh -c "$@" >$T.1 2>$T.2;S=$?;[ $S -ne 0 ]&&{ echo -e "'$@' failed with error $S\nSTDERR:\n$(cat $T.2)\nSTDOUT:\n$(cat $T.1)\n"|xmessage -file -;};rm -f $T.1 $T.2;}
    bhepple · 2009-12-31 06:59:56 0
  • 2>&1 permit to combinate stdout and stderr. grep will catch stderr and stdout instead of stdout only.


    1
    ll /root/ 2>&1 | grep -E '(psw|password)'
    strzel_a · 2010-11-11 23:02:21 0
  • In the above example 'muspi merol' (the output of the first rev command) is sent to stderr and 'lorem ipsum' (the output of the second rev command) is sent to stdout. rev reverse lines of a file or files. This use of tee allows testing if a program correctly handles its input without using files that hold the data. Show Sample Output


    2
    rev <<< 'lorem ipsum' | tee /dev/stderr | rev
    penpen · 2009-03-31 13:12:09 2

What Others Think

This is trivial, yet how the hell did I not think of it?
kaedenn · 347 weeks and 4 days ago

What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

You must be signed in to comment.

What's this?

commandlinefu.com is the place to record those command-line gems that you return to again and again. That way others can gain from your CLI wisdom and you from theirs too. All commands can be commented on, discussed and voted up or down.

Share Your Commands



Stay in the loop…

Follow the Tweets.

Every new command is wrapped in a tweet and posted to Twitter. Following the stream is a great way of staying abreast of the latest commands. For the more discerning, there are Twitter accounts for commands that get a minimum of 3 and 10 votes - that way only the great commands get tweeted.

» http://twitter.com/commandlinefu
» http://twitter.com/commandlinefu3
» http://twitter.com/commandlinefu10

Subscribe to the feeds.

Use your favourite RSS aggregator to stay in touch with the latest commands. There are feeds mirroring the 3 Twitter streams as well as for virtually every other subset (users, tags, functions,…):

Subscribe to the feed for: