Your home directory contains several files whose names begin with a period, called dot-files. When you do ``ls'' (to see a list of files in the current directory) they are not shown; do ``ls -a'' to see them. These files control the operation of various programs. Here is a list of the more commonly encountered dot-files. In most cases, if a particular dot-file is not present a reasonable default setup is used.
Here is a fuller explanation of the login dot-files. When you log in, the following scripts are executed, in order:
The directory /usr/math/default contains most of these scripts, which are publically readable. In this writeup the filename /usr/math/default is represented by $DEFAULT for brevity.
When your account is created you are given a standard .cshrc and .login, which simply "source" $DEFAULT/cshrcexp and $DEFAULT/loginexp. Loginexp begins by sourcing $DEFAULT/askterm. You also get a standard .logout which sources $DEFAULT/logoutexp.
Many users want to customize their execution environment. A file /usr/math/default/login.x contains examples and suggestions for how to do this. It is strongly recommended that you start with the standard setup by sourcing $DEFAULT/cshrcexp from .cshrc and $DEFAULT/loginexp from .login; after that you should supplement the setup rather than replacing it. This is particularly important for the path and for $HOME, the name of your home directory.
The "path" is a list of directories that is searched to find commands. From time to time in system upgrades the path is changed. If you set the path yourself, obsolete versions of commands will vanish and you will not have access to the new versions. $DEFAULT/login.x shows how to add your own directories to the path without setting the whole thing yourself. Also, directory names are automatically recognized, if existing, where you can put commands that you write yourself. See $DEFAULT/login.x for the names of these directories; if you use them you may not have to add special names to the path.
It is important never to refer explicitly to the name of your home directory or mailbox file, because your home can be moved in order to balance the load among the various machines or filesystems. Use the environment variables $HOME and $MAILDROP instead. If you do this your login customization will adapt automatically when your home directory is moved during end-of-quarter housecleaning.
When you connect to a machine from some outside terminal emulators, your terminal type will be unknown. $DEFAULT/loginexp sources $DEFAULT/askterm to set the terminal type. This script will ask you for the terminal type if it can't figure it out. If you usually or always use the same terminal type you can preset it so askterm doesn't have to ask you. See $DEFAULT/login.x for how to do this (also on dial connections).
When terminals have both a backspace (^H) and del (^?) key, the UNIX distribution generally assumes users will use del for the erase character. However, at Mathnet we have generally used ^H. Termcap has been set for ^H on most terminal types. If you are getting ^? or ^H when you think you shouldn't, be sure you indicated the correct terminal type at login. If you prefer ^? when the default is ^H, $DEFAULT/login.x shows how to customize this. If you have trouble identifying your terminal, please send mail to "bugs" and the staff will try to help. (If your editor doesn't work correctly the terminal type is probably wrong.)