1. Environment Variables
-
operating system: type
echo $OSTYPE
show detail:USER: your login name HOME: the path name of your home directory HOST: the name of the computer you are using ARCH: the architecture of the computer processor DISPLAY: the name of the computer screen to display X windows PRINTER: the default printer to send print jobs PATH: the directory the shell should search to find a command environment set:
type:setenvenvironment show:
type:printenvorenvenvironment unset:
type:unsetenv
2. Shell Variables
-
echo history: the vaule of how many shell commands to save -
cwd: current working directory -
home: the path name of your home directory -
path: the directories the shell should search to find a command -
prompt: the text string used to prompt for interactive commands shell
set or display shell variables:
type: set xxx
unset shell variables:
type: unset xxx
show all shell variables:
type: set | less
3. Using and setting variables
default file: ~/.login (C shell) or ~/.cshrc(TC shell)
~/.login: set conditions which will apply to the whole session and to perform actions that are relevant only at login.
~/.cshrc: set conditions and perform actions specific to the shell and to each invacation of it
recommand: set ENVIRONMENT variables in the .login file , and SHELL variables in the .cshrc file
warning: NEVER put commands that run graphical displays (e.g. a web browser) in your .cshrc or .login file
4. Setting shell variables in the .cshrc file
- edit
~/.cshrcfile:set history = 200 % source .cshrc% echo $history
5. Setting the path
% set path = ($path ~/xxx/xx/bin)- add this line to
.cshrcfile:set path = ($path ~/xxx/xx/bin)
