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
tee_can_split_a_pipe_in_two
owt ni epip a tilps nac eet

By: axelabs

2010-08-14 20:38:59

echo tee tr tee echo pipe tr pipes rev

1 Alternatives + Submit Alt

tee to a file descriptor

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
This is sample output - yours may be different.
```
$ bash --version |tee  >(cat - >&2) | wc -l
GNU bash, version 3.2.49(1)-release (i586-suse-linux-gnu)
Copyright (C) 2007 Free Software Foundation, Inc.
2
```
5

tee >(cat - >&2)

camocrazed · 2010-07-20 17:22:31 7

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 · 735 weeks ago

My debian show this error: tee: /dev/fd/63: File or directory not found

n158 · 610 weeks and 4 days ago

Here is the magic behind it: http://tldp.org/LDP/abs/html/process-sub.html

axelabs · 598 weeks and 4 days ago

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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?

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