A login shell first reads commands
from the files /etc/profile and then .profile in a user's home direc-
tory, if they exist. If the environment variable ENV is set on entry
to a shell, or is set in the .profile of a login shell, the shell then
subjects its value to parameter expansion and arithmetic expansion and
reads commands from the named file. Therefore, a user should place
commands that are to be executed only at login time in the .profile
file, and commands that are executed for every shell inside the ENV
file. The user can set the ENV variable to some file by placing the
following line in the file .profile in the home directory, substituting
for .shrc the filename desired:
ENV=$HOME/.shrc; export ENV