I accidentally changed /var owner/group to my username and then changed it back to root, but not all the /var folders' owners are root, so is there anyway to change back owner/group of files/folders to default state? Or at least those files/folders that are created by packages?

  • 2
    Edited because your general question was an exact duplicate of How to revert chown command? and would have been closed.
    – jw013
    Commented Oct 4, 2012 at 21:23
  • It seems there are some ways to fix this like this one but not just for /var and not just for rpm based distributions.
    – sepehr
    Commented Oct 4, 2012 at 21:32
  • Which distro are you running?
    – derobert
    Commented Oct 4, 2012 at 21:44
  • @derobert debian testing aka wheezy
    – sepehr
    Commented Oct 5, 2012 at 14:19

4 Answers 4


The simplest (and probably most correct) answer is "You can't", but if you want to try, here's a bash script that will fix the permissions of files under /var belonging to .deb packages.


  • it won't fix perms for files not belonging to a package.
  • it won't fix perms for files where the package is no longer available for download by apt-get - e.g. legacy or third-party packages.
  • AFAIK, no files in debian packages have tabs in the filename, so I've used TAB as the IFS for the while-read loop. I've checked the Contents-amd64.gz and Contents-i386.gz for debian sid and confirmed that there are no tabs, but third-party packages may have some.

The script works by generating a list of installed packages that have files in var, downloading those packages, and then using dpkg-deb -c to find out what the permissions should be.

The hardest part was writing the function to convert the permissions string (as displayed by ls -l or tar v) to an octal numeric mode, including catering for setuid, setgid, and sticky bits....some things that would be easy to write with a nice algorithm in, say, perl are too much trouble in bash, so it's easier to just brute-force it.

Finally, the script is written to be in "debug-mode" or "dry-run" mode. To make it actually change the owner/group/perms, comment-out or delete the two lines with the __EOF__ here document markers on them.

#! /bin/bash

perm_string_to_mode() {
  let perms=0
  [[ "${string}" = ?r???????? ]] && perms=$(( perms +  400 ))
  [[ "${string}" = ??w??????? ]] && perms=$(( perms +  200 ))
  [[ "${string}" = ???x?????? ]] && perms=$(( perms +  100 ))
  [[ "${string}" = ???s?????? ]] && perms=$(( perms + 4100 ))
  [[ "${string}" = ???S?????? ]] && perms=$(( perms + 4000 ))
  [[ "${string}" = ????r????? ]] && perms=$(( perms +   40 ))
  [[ "${string}" = ?????w???? ]] && perms=$(( perms +   20 ))
  [[ "${string}" = ??????x??? ]] && perms=$(( perms +   10 ))
  [[ "${string}" = ??????s??? ]] && perms=$(( perms + 2010 ))
  [[ "${string}" = ??????S??? ]] && perms=$(( perms + 2000 ))
  [[ "${string}" = ???????r?? ]] && perms=$(( perms +    4 ))
  [[ "${string}" = ????????w? ]] && perms=$(( perms +    2 ))
  [[ "${string}" = ?????????x ]] && perms=$(( perms +    1 ))
  [[ "${string}" = ?????????t ]] && perms=$(( perms + 1001 ))
  [[ "${string}" = ?????????T ]] && perms=$(( perms + 1000 ))
  echo $perms
# generate a list of installed packages that have files etc in /var
grep -l /var/ /var/lib/dpkg/info/*.list  | \
  sed -e 's:/var/lib/dpkg/info/::' -e 's/\.list$//' | \
  xargs dpkg -l | \
  awk '/^[hi]/ {print $2}' > /tmp/packages.list
# clean out the apt cache, so we only have one version of each package
apt-get clean
# download the packages as if we were going to reinstall them
# NOTE: packages which are no longer available for download
# will not have their permissions fixed.  apt-get will complain about
# those packages, so you can get a list by redirecting or tee-ing the
# output of this script.
xargs apt-get -y -d -u --reinstall install < /tmp/packages.list
for pkg in $(cat /tmp/packages.list) ; do
   if [ -e $PKGFILE ] ; then

     dpkg-deb -c /var/cache/apt/archives/${pkg}_*.deb | \
       awk -v OFS='\t' '/\.\/var\// {print $1, $2, $6}' | \
       while IFS=$'\t' read permstring ownergroup filename ; do
          # don't change owner/group/perms on symlinks
          if ! [[ "${permstring}" =~ ^l ]] ; then
            mode=$(perm_string_to_mode $permstring)
            # change "owner/group" to "owner:group" for chown
            # remove leading '.' from filename
cat <<__EOF__
            chown "$ownergroup" "$filename"
            chmod "$mode" "$filename"

The script could, of course, be quite easily adapted to fix packaged-file perms in any other directory, or in all directories.

This script would have been a lot simpler if the $packagename.list files in /var/lib/dpkg/info had owner, group, and octal perms as well as the filename...but they don't.

  • 1
    Nice. Also, you may be able to replace your grep through *.list with dpkg -S /var. Also, after applying this script, one needs to check dpkg-statoverride --list '/var/*'.
    – derobert
    Commented Oct 5, 2012 at 15:07
  • True, but dpkg -S is slow (which is why i wrote dlocate). Good point about dpkg-statoverride, though....and the output format is perfect.
    – cas
    Commented Oct 6, 2012 at 2:37
  • 1
    Thanks for the script. There's a typo in one of the sed invocations, where blank is changed to tab, it's missing the final '/'. (and while we're at it, why not just write: sed -e 's/ +/\t/g' | \
    – Chelmite
    Commented Sep 13, 2014 at 3:42
  • Wait, what? There's a typo in this? Am I going to regret running this, or does it work?
    – John Smith
    Commented Nov 17, 2023 at 9:32
  • Yeah, this is totally broken. I have no idea if it did or did not do anything, but it spit out hundreds of lines of [[: not found and Bad substitution. Continuing my streak of over 3 weeks without yet finding a working solution to a single problem I've had on SE...
    – John Smith
    Commented Nov 17, 2023 at 9:50

Similar to one of the answers above, if you have a copy of the directory with the correct permissions named "var" in your local directory, you can use the following two commands to restore permissions to the /var directory.

sudo find var -exec chown --reference="{}" "/{}" \;
sudo find var -exec chmod --reference="{}" "/{}" \;

You could.

Install the same distribution onto another machine or a VM, and use the chmod --refer to synchronize permissions for /var

  • Come on. Could this be any vaguer? I know that if I type chmod --refer and hit return, I'm going to get errors.
    – John Smith
    Commented Nov 17, 2023 at 9:32

The simple answer is "you can't".

But.... if you have a filesystem like JFS that has a log you can restore it with it's tools. Some package managers allows you to reintall it's packages and maybe with this way you can recover your files owner.

Another way but more cumbersome is that you can mount the /var at another device and than the programs will recreate the missing directory..

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