| % File src/library/base/man/file.show.Rd |
| % Part of the R package, https://www.R-project.org |
| % Copyright 1995-2015 R Core Team |
| % Distributed under GPL 2 or later |
| |
| \name{file.show} |
| \alias{file.show} |
| \title{Display One or More Text Files} |
| \description{Display one or more (plain) text files, in a platform |
| specific way, typically via a \sQuote{pager}. |
| } |
| \usage{ |
| file.show(\dots, header = rep("", nfiles), |
| title = "R Information", |
| delete.file = FALSE, pager = getOption("pager"), |
| encoding = "") |
| } |
| \arguments{ |
| \item{\dots}{one or more character vectors containing the names of the |
| files to be displayed. Paths with have \link{tilde expansion}.} |
| \item{header}{character vector (of the same length as the number of files |
| specified in \code{\dots}) giving a header for each file being |
| displayed. Defaults to empty strings.} |
| \item{title}{an overall title for the display. If a single separate |
| window is used for the display, \code{title} will be used as the window |
| title. If multiple windows are used, their titles should combine the title |
| and the file-specific header.} |
| \item{delete.file}{should the files be deleted after display? Used |
| for temporary files.} |
| \item{pager}{the pager to be used: not used on all platforms} |
| \item{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 \code{\link{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 |
| \code{pager} argument, which is a character vector specifying a system |
| command (a full path or a command found on the \env{PATH}) to run on |
| the set of files. The \sQuote{factory-fresh} default is to use |
| \file{R_HOME/bin/pager}, which is a shell script running the command-line |
| specified by the environment variable \env{PAGER} whose default is set |
| at configuration, usually to \command{less}. On a Unix-alike |
| \command{more} is used if \code{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 \code{"internal"} and |
| \code{"console"} on Windows), or by letting \code{pager} be an \R |
| function which will be called with arguments \code{(files, header, |
| title, delete.file)} corresponding to the first four arguments of |
| \code{file.show} and take care of interfacing to the GUI. |
| |
| The \command{R.app} GUI on macOS uses its internal pager irrespective |
| of the setting of \code{pager}. |
| |
| Not all implementations will honour \code{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{Ross Ihaka, Brian Ripley.} |
| \seealso{ |
| \code{\link{files}}, \code{\link{list.files}}, |
| \code{\link{help}}; |
| \code{\link{RShowDoc}} call \code{file.show()} for \code{type = |
| "text"}. Consider \code{\link{getOption}("pdfviewer")} and |
| e.g., \code{\link{system}} for displaying pdf files. |
| |
| \code{\link{file.edit}}. |
| } |
| \examples{ |
| file.show(file.path(R.home("doc"), "COPYRIGHTS")) |
| } |
| \keyword{file} |