savehistory {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)

    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.
`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 in Rgui and interactive Rterm but not in batch use of Rterm nor in embedded/DCOM versions.

The 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.putenv`.

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)

[Package utils version 2.3.1 Index]