Bash: Is it ok to use same input file as output of a piped command?

Posted by Amro on Stack Overflow See other posts from Stack Overflow or by Amro
Published on 2010-06-16T15:56:39Z Indexed on 2010/06/16 21:22 UTC
Read the original article Hit count: 212

Filed under:

linux

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bash

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unix

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shell

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pipes

Consider something like:

cat file | command > file

Is this good practice? Could this overwrite the input file as the same time as we are reading it, or is it always read first in memory then piped to second command?

Obviously I can use temp files as intermediary step, but I'm just wondering..

t=$(mktemp)
cat file | command > ${t} && mv ${t} file

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