Linux: TMOUT To Automatically Log Users Out

export TMOUT=SECONDS
export TMOUT=120

The above command will implement a 2 minute idle time-out for the default /bin/bash shell. You can edit your ~/.bash_profile or /etc/profile file as follows to define a 5 minute idle time out:

# set a 5 min timeout policy for bash shell
TMOUT=300
readonly TMOUT
export TMOUT

Save and close the file. The readonly command is used to make variables and functions readonly. In other words, your user cannot change the value of the variable called TMOUT. Consider this as a security feature.

How Do I Disable TMOUT?

To disable auto-logout, just set the TMOUT to zero or unset it as follows:
$ export TMOUT=0
or
$ unset TMOUT
Please note that readonly variable can only be disabled by root user in /etc/profile or ~/.bash_profile.

A Note About TCSH SHELL and OpenSSH Server/Client

SSH allows administrators to set an idle timeout interval in /etc/ssh/sshd_config file. TCSH user should use autologout variable. Please see our previous FAQ “Linux / UNIX Automatically Log BASH / TCSH / SSH Users Out After a Period of Inactivity” for more information.

Conclusion

TMOUT is a bash variable to auto-logout Linux users when there isn’t any activity. When we set TMOUT value greater than zero, TMOUT is treated as the default timeout for the read command. The select command terminates if the input does not arrive after TMOUT seconds when information is coming from a terminal. In an interactive shell, the value is interpreted as the number of seconds to wait for a line of input after issuing the primary prompt. Bash terminates after waiting for that number of seconds if a complete line of information does not arrive. Read bash man page for more information by typing the following man command:
$ man bash