Find out which process is changing a file

Solution 1:

You can use auditing to find this. If not already available, install and enable auditing for your distro.

set an audit watch on /etc/hosts

/sbin/auditctl -w /etc/hosts -p war -k hosts-file

-w watch /etc/hosts
-p warx watch for write, attribute change, execute or read events
-k hosts-file is a search key.

Wait till the hosts file changes and then use ausearch to seer what is logged

/sbin/ausearch -f /etc/hosts | more

You'll get masses of output e.g.

> time->Wed Oct 12 09:34:07 2011 type=PATH
> msg=audit(1318408447.180:870): item=0 name="/etc/hosts" inode=2211062
> dev=fd:00 mode=0100644 ouid=0 ogid=0 rdev=00:00
> obj=system_u:object_r:etc_t:s0 type=CWD msg=audit(1318408447.180:870):
> cwd="/home/iain" type=SYSCALL msg=audit(1318408447.180:870):
> arch=c000003e syscall=2 success=yes exit=0 a0=7fff73641c4f a1=941
> a2=1b6 a3=3e7075310c items=1 **ppid=7259**  **pid=7294** au id=1001 uid=0 gid=0
> euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts0 ses=123 
> comm="touch" **exe="/bin/touch"** subj=user_u:system_r:unconfined_t:s0
> key="hosts-file"

In this case I used the touch command to change the files timstamp it's pid was 7294 and it's ppid was 7259 (my shell).

Solution 2:

After a lot of search, I found the solution, just use this command: sudo fs_usage | grep [path_to_file]

Solution 3:

You can also use inotify-tools:

  inotifywait -mq -e open -e modify /etc/hosts