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append content of a file to itself

Terminal - append content of a file to itself
cat file | tee >> file
2009-07-30 07:34:03
User: GeckoDH
Functions: cat file tee
0
append content of a file to itself

The command `cat file >> file` failes with the following error message:

cat: file: input file is output file

`tee` is a nice workaround without using any temporary files.

Alternatives

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Terminal - Alternatives

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What others think

Could you please tell us at least one reason we would duplicate a file in itself ?

Comment by CodSpirit 309 weeks and 5 days ago

it looks like you mean to use > rather than >> here, because depending on when cat takes a break reading "file" and when the shell writes the incoming data you could end up with a file that just keeeeeeepppps groooooowing.

Comment by bwoodacre 309 weeks and 3 days ago

For me its nice if I need to generate a test file with a, say, 10 chunks of identical 100,000 lines in it. So it's quicker to append the file to itself 10 times than write out 100,000 lines 10 times. But (ironically) this way didn't work for me (the file kept growing), so intermediate file is not a bad alternative. Maybe it's because the file is so gigantic, but oh well...

Comment by tefrak 174 weeks and 1 day ago

Your point of view

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