$ id
uid=1000(kev) gid=1000(kev) groups=1000(kev),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),109(lpadmin),124(sambashare)

$ ls -l /etc/sudoers
-r--r----- 1 root root 723 Jan 31  2012 /etc/sudoers

$ sudo adduser kev root
Adding user `kev' to group `root' ...
Adding user kev to group root

$ cat /etc/sudoers
cat: /etc/sudoers: Permission denied

After adding myself(kev) to group root, I still cannot read /etc/sudoers.

I don't know why. Thanks for your help.

2 Answers 2


You need to log out and back in again for the change to take effect.

  • 1
    If you'd prefer refreshing groups w/o logging out, then check harayz's answer. Nov 11, 2016 at 12:21

To refresh group membership of the user kev without logging out:

exec su -l kev

To make groupname your default group for the entire session:

newgrp groupname

To print current groups you're a member of (source):


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