UNIX for Advanced & Expert Users

       HISTCONTROL
	      A colon-separated list of values controlling  how  commands  are
	      saved  on  the  history  list.   If  the list of values includes
	      ignorespace, lines which begin with a space  character  are  not
	      saved  in  the history list.  A value of ignoredups causes lines
	      matching the previous history entry to not be saved.  A value of
	      ignoreboth is shorthand for ignorespace and ignoredups.  A value
	      of erasedups causes all previous lines matching the current line
	      to  be  removed from the history list before that line is saved.
	      Any value not in the above list is ignored.  If  HISTCONTROL  is
	      unset,  or does not include a valid value, all lines read by the
	      shell parser are saved on the history list, subject to the value
	      of  HISTIGNORE.  The second and subsequent lines of a multi-line
	      compound command are not tested, and are added  to  the  history
	      regardless of the value of HISTCONTROL.
       HISTFILE
	      The name of the file in which command history is saved (see HIS-
	      TORY below).  The default value is ~/.bash_history.   If	unset,
	      the  command  history  is  not  saved  when an interactive shell
	      exits.
       HISTFILESIZE
	      The maximum number of lines contained in the history file.  When
	      this  variable  is  assigned  a value, the history file is trun-
	      cated, if necessary, by removing the oldest entries, to  contain
	      no  more	than  that number of lines.  The default value is 500.
	      The history file is also truncated to this size after writing it
	      when an interactive shell exits.
       HISTIGNORE
	      A  colon-separated list of patterns used to decide which command
	      lines should be saved on the  history  list.   Each  pattern  is
	      anchored	at  the  beginning of the line and must match the com-
	      plete line (no implicit  `*'  is	appended).   Each  pattern  is
	      tested  against  the line after the checks specified by HISTCON-
	      TROL are applied.  In  addition  to  the	normal	shell  pattern
	      matching characters, `&' matches the previous history line.  `&'
	      may be escaped using  a  backslash;  the	backslash  is  removed
	      before attempting a match.  The second and subsequent lines of a
	      multi-line compound command are not tested, and are added to the
	      history regardless of the value of HISTIGNORE.
       HISTSIZE
	      The  number  of commands to remember in the command history (see
	      HISTORY below).  The default value is 500.