Uncovering Default Shell Environment Variables

The bash shell uses specific environment variables by default to define the system environment. You can always count on these variables being set or available to be set on your Linux system. Because the bash shell is a derivative of the original Unix Bourne shell, it also includes environment variables originally defined in that shell.

Table 6.1 shows the environment variables that the bash shell provides that are compatible with the original Unix Bourne shell.

Table 6.1 The bash Shell Bourne Variables

Variable	Description
CDPATH	A colon-separated list of directories used as a search path for the cd command
HOME	The current user's home directory
IFS	A list of characters that separate fields used by the shell to split text strings
MAIL	The filename for the current user's mailbox (The bash shell checks this file for new mail.)
MAILPATH	A colon-separated list of multiple filenames for the current user's mailbox...