Solved: su: failed to execute /bin/ksh: Resource temporarily unavailable ?

Today we will see one of the most common error message and its solution.

I. Error Message

[root@ngelinux orasystem]# su - oracle
Last login: Fri Jun 23 01:48:02 PDT 2023 on pts/5
su: failed to execute /bin/ksh: Resource temporarily unavailable

II. Solution
The error occurs when that particular user is not able to fork new process and hence it failed to switch to that user.

# cat /etc/security/limits.conf
or,
# cat /etc/security/limits.d/20-nproc.conf
# Default limit for number of user's processes to prevent
# accidental fork bombs.
# See rhbz #432903 for reasoning.

* soft nproc 4096
root soft nproc unlimited
oracle soft nproc unlimited
#

III. Test
After changing the limits file, lets test this by switching to that user.

[root@ngelinux ~]# su - oracle
Last login: Fri Jun 23 01:52:27 PDT 2023 on pts/5
The Oracle base remains unchanged with value /usr/orasystem/app/oracle/
/usr/orasysstem
oracle:/usr/orasystem>

Tags: centoserrorhardlimitlinuxnprocoracleresourcerhelsoftsolutionsolvedsutemporarilyunavailableunixunlimited