Variables used within Shell Scripts
- System variable to return the Process ID of the script
- System variable to return the first command line parameter
- User-defined variable for counting in a loop
- Environment variable containing the current user’s home directory path
- User-defined variable to hold a constant value referenced in the script
- environment variable containing the operating system name
Variables in Bourne shell
Variables in the Bourne shell are more straightforward and homogeneous than in the C shell, and are treated more consistently.
There are no special variables that are propagated from shell to environment variables, and vice versa. There is only one command to set a normal variable, and one command to make any variable into an environment variable. In sh, to set a key equal to a value, the syntax is:
Note that it is important that no spaces be included between the variable and the value to which it is being set. To make a variable visible to the environment, it must be "'exported". The shell builtin export is designed for this task.
prompt$ key=value
Note that it is important that no spaces be included between the variable and the value to which it is being set. To make a variable visible to the environment, it must be "'exported". The shell builtin export is designed for this task.
Linux Shell Scripting