savehistory              package:utils              R Documentation

_L_o_a_d _o_r _S_a_v_e _o_r _D_i_s_p_l_a_y _t_h_e _C_o_m_m_a_n_d_s _H_i_s_t_o_r_y

_D_e_s_c_r_i_p_t_i_o_n:

     Load or save or display the commands history.

_U_s_a_g_e:

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

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

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

_A_r_g_u_m_e_n_t_s:

    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.

_D_e_t_a_i_l_s:

     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' command-line interface and the 'R.app'
     Mac OS X console, 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'.

     Note that 'readline' history library save files with permission
     '0600', that is with read/write permission for the user and not
     even read permission for any other account.

     '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
     support timestamps) only the console message is printed.

_N_o_t_e:

     If you want to save the history at the end of (almost) every
     interactive session (even those in which you do not save the
     workspace), you can put a call to 'savehistory()' in '.Last'.  See
     the examples.

_E_x_a_m_p_l_e_s:

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