The user root can't do `su` to any other user and gets `Permission denied` Error.

Issue

• When trying to su to a user id from root , it gives the below error message .

# su - test
su: /usr/bin/ksh: Permission denied

• The permissions for the ksh file are verified with the working servers and everything is the same .

# ls -l /usr/bin/ksh
lrwxrwxrwx 1 root root 28 Apr 12  2010 /usr/bin/ksh -> /etc/alternatives/ksh-usrbin
# ls -l /etc/alternatives/ksh-usrbin
lrwxrwxrwx 1 root root 10 Mar 29 08:27 /etc/alternatives/ksh-usrbin -> /bin/ksh93
# ls -l /bin/ksh93
-rwxr-xr-x 1 root root 1302432 Jun 28 08:08 /bin/ksh93