unix shell, redirect output but keep on stdin

Question

I'd like to have a shell script redirect stdout of a child process in the following manner

I know I could do something like

#!/bin/sh

./child > file
cat file

But that would not display stdout in real time. For instance, if the child was

#!/bin/sh

echo 1
sleep 1
echo 2

The user would see "1" and "2" printed at the same time

Dennis Williamson · Accepted Answer · 2010-05-17 19:33:55Z

14

Use tee:

./child | tee file

tee will copy its standard input to any file on the command line and to standard output as well.

Dennis Williamson

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answered May 17, 2010 at 17:47

R Samuel Klatchko

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1 Comment

Another tip: 'tee -a' is for appending to files if you want that, equivalent to using >> instead of > with normal shell redirection.

ebal · Accepted Answer · 2010-05-18 18:40:08Z

-1

you can do something like that:

$ grep something largefile | sponge largefile

answered May 18, 2010 at 18:40

ebal

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How does it fullfill "Display the output of the process in real time"?