Use tee to process a pipe with two or more processes

echo "tee can split a pipe in two"|tee >(rev) >(tr ' ' '_')
Tee can be used to split a pipe into multiple streams for one or more process to work it. You can add more " >()" for even more fun.
Sample Output
tee can split a pipe in two
owt ni epip a tilps nac eet

By: axelabs
2010-08-14 20:38:59

1 Alternatives + Submit Alt

  • the tee command does fine with file names, but not so much with file descriptors, such as &2 (stderr). This uses process redirection to tee to the specified descriptor. In the sample output, it's being used to tee to stderr, which is connected with the terminal, and to wc -l, which is also outputting to the terminal. The result is the output of bash --version followed by the linecount Show Sample Output

    tee >(cat - >&2)
    camocrazed · 2010-07-20 17:22:31 3

What Others Think

Cool trick! Unfortunately Cygwin has a bug in 1.7 that prevents this from working. AIX also has problems with it - it runs once but hangs after that. I thought it was leaving pipes around but it still hangs if I delete them from /tmp. Any help is much appreciated.
randy909 · 596 weeks and 6 days ago
My debian show this error: tee: /dev/fd/63: File or directory not found
n158 · 472 weeks and 2 days ago
Here is the magic behind it:
axelabs · 460 weeks and 2 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? 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.


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: