savehistory              package:utils              R Documentation

Load or Save or Display the Commands History

Description:

     Load or save or display the commands history.

Usage:

     loadhistory(file = ".Rhistory")
     savehistory(file = ".Rhistory")

     history(max.show = 25, reverse = FALSE, pattern, ...)

     timestamp(stamp = date(),
               prefix = "##------ ", suffix = " ------##",
               quiet = FALSE)

Arguments:

    file: The name of the file in which to save the history, or from
          which to load it. The path is relative to the current working
          directory.

max.show: The maximum number of lines to show. 'Inf' will give all of
          the currently available history.

 reverse: logical. If true, the lines are shown in reverse order. Note:
          this is not useful when there are continuation lines.

 pattern: A character string to be matched against the lines of the
          history

     ...: Arguments to be passed to 'grep' when doing the matching.

   stamp: A value or vector of values to be written into the history.

  prefix: A prefix to apply to each line.

  suffix: A suffix to apply to each line.

   quiet: If 'TRUE', suppress printing timestamp to the console.

Details:

     There are several history mechanisms available for the different R
     consoles, which work in similar but not identical ways.  Other
     uses of R, in particular embedded uses, may have no history. This
     works under the 'readline' and GNOME and MacOS X consoles, but not
     otherwise (for example, in batch use or in an embedded
     application).

     The 'readline' history mechanism is controlled by two environment
     variables: 'R_HISTSIZE' controls the number of lines that are
     saved (default 512), and 'R_HISTFILE' sets the filename used for
     the loading/saving of history if requested at the beginning/end of
     a session (but not the default for these functions).  There is no
     limit on the number of lines of history retained during a session,
     so setting 'R_HISTSIZE' to a large value has no penalty unless a
     large file is actually generated.

     These variables are read at the time of saving, so can be altered
     within a session by the use of 'Sys.setenv'.

     'history' shows only unique matching lines if 'pattern' is
     supplied.

     The 'timestamp' function writes a timestamp (or other message)
     into the history and echos it to the console.  On platforms that
     do not  support a history mechanism (where the mechanism does not
     yet support timestamps) only the console message is printed.

Note:

     If you want to save the history (almost) every session, you can
     put a call to 'savehistory()' in '.Last'.  See the examples.

Examples:

     ## Not run: 
     .Last <- function()
         if(interactive()) try(savehistory("~/.Rhistory"))
     ## End(Not run)

