Bash Shell Variables

Bash Shell Variables

The Bash shell has numerous variables that contain useful information. They are indicated by the following pattern: $VARIABLE_NAME.

We won’t look at all of the Bash Shell Variables, but we would like you to know about four of them:

• $BASH
• $HOME
• $PATH
• $BASHPID

To view the contents of any Bash Shell variable you can simply use the variable as the argument with the echo command.

echo $BASH

The $BASH shell variable contains the absolute path to the shell this session is using.

echo $HOME

The $HOME shell variable contains the absolute path to the home directory of the user that initiated the Bash shell.

echo $PATH

The $PATH shell variable contains a collection of all of the tools currently accessible to this current Bash Shell session.

Any files and subdirectories found within the listed directories are available to be invoked by name.

echo $BASHPID

The $BASHPID shell variable contains the process ID of the current Bash Shell. This number will likely be different for everyone. In fact if you open your current terminal and open a new one and then check the $BASHPID shell variable you should notice that it is different.

Every running program has at least one process running and therefore a process ID. Many programs will create multiple processes and each of their children processes will have unique IDs, however the program’s initial main process is the parent of all other associated process IDs.