history: Managing the History File

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1 2.3.6 Managing the History File
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1 The History library can read the history from and write it to a file.
1 This section documents the functions for managing a history file.
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1  -- Function: int read_history (const char *filename)
1      Add the contents of FILENAME to the history list, a line at a time.
1      If FILENAME is 'NULL', then read from '~/.history'.  Returns 0 if
1      successful, or 'errno' if not.
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1  -- Function: int read_history_range (const char *filename, int from,
1           int to)
1      Read a range of lines from FILENAME, adding them to the history
1      list.  Start reading at line FROM and end at TO.  If FROM is zero,
1      start at the beginning.  If TO is less than FROM, then read until
1      the end of the file.  If FILENAME is 'NULL', then read from
1      '~/.history'.  Returns 0 if successful, or 'errno' if not.
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1  -- Function: int write_history (const char *filename)
1      Write the current history to FILENAME, overwriting FILENAME if
1      necessary.  If FILENAME is 'NULL', then write the history list to
1      '~/.history'.  Returns 0 on success, or 'errno' on a read or write
1      error.
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1  -- Function: int append_history (int nelements, const char *filename)
1      Append the last NELEMENTS of the history list to FILENAME.  If
1      FILENAME is 'NULL', then append to '~/.history'.  Returns 0 on
1      success, or 'errno' on a read or write error.
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1  -- Function: int history_truncate_file (const char *filename, int
1           nlines)
1      Truncate the history file FILENAME, leaving only the last NLINES
1      lines.  If FILENAME is 'NULL', then '~/.history' is truncated.
1      Returns 0 on success, or 'errno' on failure.
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