Shell timeouts

From Brandonhutchinson.com

To terminate sessions after a period of inactivity, use the following shell variables:

bash/ksh

    TMOUT
         If set to a value  greater  than  zero,  the  value  is
         interpreted  as the number of seconds to wait for input
         after issuing  the  primary  prompt.   Bash  terminates
         after  waiting for that number of seconds if input does
         not arrive.

csh/tcsh

    The autologout shell variable can be set to log out or  lock
    the shell after a given number of minutes of inactivity.

• set autlogout=minutes

Bourne shell

• The Bourne shell has no TMOUT variable nor equivalent [1].