bash: Bourne Shell Variables

1 
1 5.1 Bourne Shell Variables
1 ==========================
1 
1 Bash uses certain shell variables in the same way as the Bourne shell.
1 In some cases, Bash assigns a default value to the variable.
1 
1 'CDPATH'
1      A colon-separated list of directories used as a search path for the
1      'cd' builtin command.
1 
1 'HOME'
1      The current user's home directory; the default for the 'cd' builtin
1      command.  The value of this variable is also used by tilde
1      expansion (⇒Tilde Expansion).
1 
1 'IFS'
1      A list of characters that separate fields; used when the shell
1      splits words as part of expansion.
1 
1 'MAIL'
1      If this parameter is set to a filename or directory name and the
1      'MAILPATH' variable is not set, Bash informs the user of the
1      arrival of mail in the specified file or Maildir-format directory.
1 
1 'MAILPATH'
1      A colon-separated list of filenames which the shell periodically
1      checks for new mail.  Each list entry can specify the message that
1      is printed when new mail arrives in the mail file by separating the
1      filename from the message with a '?'.  When used in the text of the
1      message, '$_' expands to the name of the current mail file.
1 
1 'OPTARG'
1      The value of the last option argument processed by the 'getopts'
1      builtin.
1 
1 'OPTIND'
1      The index of the last option argument processed by the 'getopts'
1      builtin.
1 
1 'PATH'
1      A colon-separated list of directories in which the shell looks for
1      commands.  A zero-length (null) directory name in the value of
1      'PATH' indicates the current directory.  A null directory name may
1      appear as two adjacent colons, or as an initial or trailing colon.
1 
1 'PS1'
11      The primary prompt string.  The default value is '\s-\v\$ '.  ⇒
      Controlling the Prompt, for the complete list of escape sequences
1      that are expanded before 'PS1' is displayed.
1 
1 'PS2'
1      The secondary prompt string.  The default value is '> '.
1