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Empty a file

Terminal - Empty a file
> file.txt
2009-01-26 10:22:31
User: root
217
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 7 alternatives - vote for the best!

Terminal - Alternatives
> file
2010-12-26 14:17:13
User: Juev
9
Up
Down
Create a new file
Comments (0) | Add to favourites | Report as malicious
:> file
2010-09-23 12:33:55
User: krissi
6
Up
Down
Empty a file
Comments (0) | Add to favourites | Report as malicious
truncate -s0 file
2009-10-24 16:31:03
User: pipping
5
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 (1) | Add to favourites | Report as malicious
> foobar.txt
2009-12-29 08:08:15
User: unixmonkey7657
4
Up
Down
Empty a file
Comments (1) | Add to favourites | Report as malicious
> [filename]
2011-05-18 14:59:02
User: bbbco
Tags: redirect Linux UNIX touch
-3
Up
Down
Empty a file of contents

Ever need to erase the contents of a file and start over from scratch? This easy command allows you to do so. Be warned! This will immediately erase all the contents of your file and start you over from scratch (i.e. your file will be at 0 bytes, like if you touch a file).

Show sample output | Comments (3) | 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 157 weeks and 4 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 157 weeks and 1 day 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 156 weeks and 2 days ago

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

: > foo

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

Comment by laburu 156 weeks and 1 day ago

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

Comment by pixelbeat 156 weeks and 1 day 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 156 weeks 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 152 weeks and 5 days ago

Excellent! Just what I was looking for

Comment by xenon87 151 weeks and 4 days ago

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

>| file.txt

Comment by rtmhal 150 weeks and 3 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 137 weeks ago

Perfect for clearing log files :)

Comment by okuehn 121 weeks ago

Useful trick, thanks

One more question: if i need to not change the time of the emptied file?

How can i do?

thanks in advance

Comment by bugmenot 68 weeks and 2 days ago

That is very nice also becouse '>' command preserves the permissions

Comment by carlesso 55 weeks and 3 days ago

Your point of view

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