history: History Variables

1 
1 2.4 History Variables
1 =====================
1 
1 This section describes the externally-visible variables exported by the
1 GNU History Library.
1 
1  -- Variable: int history_base
1      The logical offset of the first entry in the history list.
1 
1  -- Variable: int history_length
1      The number of entries currently stored in the history list.
1 
1  -- Variable: int history_max_entries
1      The maximum number of history entries.  This must be changed using
1      'stifle_history()'.
1 
1  -- Variable: int history_write_timestamps
1      If non-zero, timestamps are written to the history file, so they
1      can be preserved between sessions.  The default value is 0, meaning
1      that timestamps are not saved.
1 
1      The current timestamp format uses the value of HISTORY_COMMENT_CHAR
1      to delimit timestamp entries in the history file.  If that variable
1      does not have a value (the default), timestamps will not be
1      written.
1 
1  -- Variable: char history_expansion_char
1      The character that introduces a history event.  The default is '!'.
1      Setting this to 0 inhibits history expansion.
1 
1  -- Variable: char history_subst_char
1      The character that invokes word substitution if found at the start
1      of a line.  The default is '^'.
1 
1  -- Variable: char history_comment_char
1      During tokenization, if this character is seen as the first
1      character of a word, then it and all subsequent characters up to a
1      newline are ignored, suppressing history expansion for the
1      remainder of the line.  This is disabled by default.
1 
1  -- Variable: char * history_word_delimiters
1      The characters that separate tokens for 'history_tokenize()'.  The
1      default value is '" \t\n()<>;&|"'.
1 
1  -- Variable: char * history_search_delimiter_chars
1      The list of additional characters which can delimit a history
1      search string, in addition to space, TAB, ':' and '?' in the case
1      of a substring search.  The default is empty.
1 
1  -- Variable: char * history_no_expand_chars
1      The list of characters which inhibit history expansion if found
1      immediately following HISTORY_EXPANSION_CHAR.  The default is
1      space, tab, newline, carriage return, and '='.
1 
1  -- Variable: int history_quotes_inhibit_expansion
1      If non-zero, double-quoted words are not scanned for the history
1      expansion character or the history comment character.  The default
1      value is 0.
1 
1  -- Variable: rl_linebuf_func_t * history_inhibit_expansion_function
1      This should be set to the address of a function that takes two
1      arguments: a 'char *' (STRING) and an 'int' index into that string
1      (I).  It should return a non-zero value if the history expansion
1      starting at STRING[I] should not be performed; zero if the
1      expansion should be done.  It is intended for use by applications
1      like Bash that use the history expansion character for additional
1      purposes.  By default, this variable is set to 'NULL'.
1