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(4) Logging In

Logging in and Initialization Files

During log in a shell is started in your home directory (echo $shell) , (grep richard /etc/passwd)
Home directories can contain special files that are read at log in time and when shells start up, these initialization files tell the shell and your environment how to set up
Initialization Files
- File ".login" runs when you login (more .login)
- File ".cshrc" runs when csh, tcsh starts
- Other configuration files (".logout",".profile",".newsrc",".emacs",".forward")
- Initialization files set up variables/environment and can be changed by the user
Environment variables are set in .login
- env will show you current environment variables
- To set variables: setenv variable_name value
  e.g. setenv DISPLAY kronos:0
- To unset (remove) variables: unsetenv variable_name,
  e.g. unsetenv PRINTER)
".cshrc" read by csh, tcsh
- To see shell variables that are set, e.g. echo $path, (echo $variable_name), the ($) tells the shell that you want the the next text string to be treated like a variable, substitute the value before evaluating the command
- The shell also has local variables (used internally, not passed to other programs), (set)
- To set, e.g. set path = /usr/local/bin , (set [variable_name] = [value], set path = ($path /usr/local/bin))
- To unset, unset path, (unset [variable_name])

slide04.src last modified Feb 8, 2011

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