How do erase the contents of a error.log file but keep the file intact

Question

I want to erase the contents of the file error.log (nginx error log file), but I don't want to actually delete the file.

is this possible?

running ubuntu

Dennis Williamson · Accepted Answer · 2010-12-04 03:16:21Z

74

You can use this:

>error.log

(typed just like that - an empty output redirection)

or

truncate -s0 error.log

answered Dec 4, 2010 at 3:16

Dennis Williamson

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@Ignacio: If the file already exists, either will truncate it. If the file doesn't exist, either will create it.
– Dennis Williamson
Dec 4, 2010 at 3:21
You're right, my bad.
– Ignacio Vazquez-Abrams
Dec 4, 2010 at 3:24
The last option worked for me, for some reason sudo >error.log didnt work for me (ubuntu 12.04)
– davidkonrad
May 19, 2014 at 10:38
5

@davidkonrad: You would have to already be root for the redirection to work since it's performed before sudo takes effect. Or you can do sudo bash -c '>error.log'
– Dennis Williamson
May 19, 2014 at 10:56
1

@divHelper11: In my answer I say it's an "empty output redirection". That means that "nothing" is being sent to the named file and that overwrites any existing contents. It's similar to echo "some words" > output.txt but nothing is going in.
– Dennis Williamson
Oct 25, 2018 at 16:46

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Ignacio Vazquez-Abrams · Accepted Answer · 2010-12-04 03:04:40Z

2

You'll confuse the daemon. Erase the file then send SIGHUP to nginx.

answered Dec 4, 2010 at 3:04

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SIGHUP? Can't I shut nginx down, purge the file, then start? I want to know how to erase the file for knowledge sake also.
– user27449
Dec 4, 2010 at 3:14
If you wanted to, sure. But that would disrupt service.
– Ignacio Vazquez-Abrams
Dec 4, 2010 at 3:15
I think both a null redirection and a truncate are atomic, so as long as no seeking is going on (especially if the only operation that's occurring is appending) it shouldn't be disruptive.
– Dennis Williamson
Dec 4, 2010 at 3:25

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