R: Display One or More Text Files

file.show {base} | R Documentation

## Display One or More Text Files

### Description

Display one or more (plain) text files, in a platform specific way, typically via a ‘pager’.

### Usage

    file.show(..., header = rep("", nfiles),
              title = "R Information",
              delete.file = FALSE, pager = getOption("pager"),
              encoding = "")

### Arguments

`...` | one or more character vectors containing the names of the files to be displayed. Paths with have tilde expansion.
`header` | character vector (of the same length as the number of files specified in `...`) giving a header for each file being displayed. Defaults to empty strings.
`title` | an overall title for the display. If a single separate window is used for the display, `title` will be used as the window title. If multiple windows are used, their titles should combine the title and the file-specific header.
`delete.file` | should the files be deleted after display? Used for temporary files.
`pager` | the pager to be used: not used on all platforms
`encoding` | character string giving the encoding to be assumed for the file(s).

### Details

This function provides the core of the R help system, but it can be used for other purposes as well, such as `page`.

How the pager is implemented is highly system-dependent.

The basic Unix version concatenates the files (using the headers) to a temporary file, and displays it in the pager selected by the `pager` argument, which is a character vector specifying a system command (a full path or a command found on the PATH) to run on the set of files. The ‘factory-fresh’ default is to use ‘R_HOME/bin/pager’, which is a shell script running the command-line specified by the environment variable PAGER whose default is set at configuration, usually to `less`. On a Unix-alike `more` is used if `pager` is empty.

Most GUI systems will use a separate pager window for each file, and let the user leave it up while R continues running. The selection of such pagers could either be done using special pager names being intercepted by lower-level code (such as `"internal"` and `"console"` on Windows), or by letting `pager` be an R function which will be called with arguments `(files, header, title, delete.file)` corresponding to the first four arguments of `file.show` and take care of interfacing to the GUI.

The `R.app` GUI on macOS uses its internal pager irrespective of the setting of `pager`.

Not all implementations will honour `delete.file`. In particular, using an external pager on Windows does not, as there is no way to know when the external application has finished with the file.

### Author(s)

Ross Ihaka, Brian Ripley.

### See Also

`files`, `list.files`, `help`; `RShowDoc` call `file.show()` for `type = "text"`. Consider `getOption("pdfviewer")` and e.g., `system` for displaying pdf files.

`file.edit`.

### Examples

    file.show(file.path(R.home("doc"), "COPYRIGHTS"))

[Package base version 3.5.1 Index]