3.2.4.1.
Bourne shell reserved variables
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Bash uses certain shell variables in the same way as the Bourne shell. In some cases, Bash assigns a default value to the variable. The table below gives an overview of these plain shell variables:
Table 3-1. Reserved Bourne shell variables
| Variable name | Definition |
|---|---|
| CDPATH | A colon-separated list of directories used as a search path for the cd built-in command. |
| HOME | The current user's home directory; the default for the cd built-in. The value of this variable is also used by tilde expansion. |
| IFS | A list of characters that separate fields; used when the shell splits words as part of expansion. |
| If this parameter is set to a file name and the MAILPATH variable is not set, Bash informs the user of the arrival of mail in the specified file. | |
| MAILPATH | A colon-separated list of file names which the shell periodically checks for new mail. |
| OPTARG | The value of the last option argument processed by the getopts built-in. |
| OPTIND | The index of the last option argument processed by the getopts built-in. |
| PATH | A colon-separated list of directories in which the shell looks for commands. |
| PS1 | The primary prompt string. The default value is "'\s-\v\$ '". |
| PS2 | The secondary prompt string. The default value is "'> '". |
