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sh, bash, ksh, ash
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bash, ash - has alias

1. run /etc/profile
2. run ~/.profile
   Place commands to be executed only at login
   in .profile.
3. if $ENV is set, read commands from file
   specified in $ENV (bash uses BASH_ENV)
   
. file - commands in the specified file are
  read and executed by the shell. (in bash,
  the word 'source' can also be used). 



-------------------
csh, tcsh
-------------------

1. run .cshrc
2. run .login

use setenv to cause environment variables
to persist from parent to child process.

can call commands from other files using
'source' command

========================
aliases

ksh has aliases and can export them with
'alias -x'. sh does not have aliases and
bash does, but I can't find a way to
export them.

Perhaps the only solution is to eliminate
the use of aliases and do things in wrappers
instead - one wrapper for each program.

A pain in the ass, but it may be the only way
with these shells.