Find that your shell is logging you out after a certain period of inactivity? You can tweak the number of seconds before the logout, or disable auto logout completely. In the instructions below, zero (0) disables auto logout or replace 0 with number for timeout seconds.
Disable Auto Logout in bash or sh
bash$ export TMOUT=0
Disable Auto Logout in csh or tcsh
tcsh% set autologout=0