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Empty a file

Terminal - Empty a file
> file.txt
2009-01-26 10:22:31
User: root
112
Up
Down
Empty a file

For when you want to flush all content from a file without removing it (hat-tip to Marc Kilgus).

Add to favourites | Report as malicious

Alternatives

There are 2 alternatives - vote for the best!

Terminal - Alternatives
> foobar.txt
2009-12-29 08:08:15
User: unixmonkey7657
3
Up
Down
Empty a file
Comments (1) | Add to favourites | Report as malicious
truncate -s0 file
2009-10-24 16:31:03
User: pipping
2
Up
Down
Empty a file

The downside of output redirection is that you need permissions. So something like

> file

won't play nicely w/ sudo. You'd need to do something like

bash -c '> file'

instead, you could go w/

sudo truncate -s0 file
Comments (0) | Add to favourites | Report as malicious

Know a better way?

If you can do better, submit your command here.

What others think

Nice one! Some thing in *nix are so simple that you'd never imagine they exist :)

Comment by evad 58 weeks and 6 days ago

cat > file.txt followed by shift+ins allows you to insert your buffer content into file. ^d to finish the process

Comment by boombastic 58 weeks and 3 days ago

A similar useful trick which works with things like sudo and pfexec is "cp /dev/null file.txt"; that way you don't have to switch to another account to empty files which you do not own.

Comment by systemj 57 weeks and 3 days ago

To avert surprises, prepend ":" to perform specified redirections reliably:

: > foo

FWIW, the (built-in) null command ":" also expands arguments.

Comment by laburu 57 weeks and 2 days ago

laburu can you expand on the reliability issue you're referring to?

Comment by pixelbeat 57 weeks and 2 days ago

This is especially useful with large files that need to be cleared. I've run across a situation where the inodes ran out on the hd because people kept cat'ing /dev/null and redirecting it to file. That method kept the inodes locked.

Comment by leprasmurf 57 weeks and 1 day ago

It should be noted that this is a Bash-ism. This will hang in ZSH and throw an error to STDERR with BSD-CSH.

Comment by atoponce 54 weeks ago

Excellent! Just what I was looking for

Comment by xenon87 52 weeks and 5 days ago

If you've done set -o noclobber the command will need to be:

>| file.txt

Comment by rtmhal 51 weeks and 4 days ago

This is not just a is a Bash-ism it works fine on the korn shell too.. tested on ksh/HP-UX.

Comment by zlemini 38 weeks and 1 day ago

Perfect for clearing log files :)

Comment by okuehn 22 weeks and 2 days ago

Your point of view

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