% File src/library/tools/man/Rdiff.Rd
% Part of the R package, https://www.R-project.org
% Copyright 2010-2017 R Core Team
% Distributed under GPL 2 or later

\name{Rdiff}
\alias{Rdiff}
\title{Difference R Output Files}
\description{
  Given two \R output files, compute differences ignoring headers,
  footers and some other differences.
}
\usage{
Rdiff(from, to, useDiff = FALSE, forEx = FALSE,
      nullPointers = TRUE, Log = FALSE)
}
\arguments{
  \item{from, to}{filepaths to be compared}
  \item{useDiff}{should \command{diff} always be used to compare
    results?}
  \item{forEx}{logical: extra pruning for \file{-Ex.Rout} files to
    exclude the header.}
  \item{nullPointers}{logical: should the displayed addresses of
    pointers be set to \code{0x00000000} before comparison?}
  \item{Log}{logical: should the returned value include a log of
    differences found?}
}
\details{
  
  The \R startup banner and any timing information from \command{R CMD
    BATCH} are removed from both files, together with lines about
  loading packages.  UTF-8 fancy quotes (see \code{\link{sQuote}}) and
  on Windows, Windows' so-called \sQuote{smart quotes}, are mapped to
  a simple quote.  Addresses of environments, compiled bytecode and
  other exotic types expressed as hex addresses
  (e.g., \code{<environment: 0x12345678>}) are mapped to
  \code{0x00000000}.  The files are then compared line-by-line.  If
  there are the same number of lines and \code{useDiff} is false, a
  simple \command{diff -b} -like display of differences is printed
  (which ignores trailing spaces and differences in numbers of
  consecutive spaces), otherwise \command{diff -bw} is called on the
  edited files.  (This tries to ignore all differences in whitespace:
  note that flag \option{-w} is not required by POSIX but is supported
  by GNU, Solaris and FreeBSD versions.)

  This can compare uncompressed PDF files, ignoring differences in
  creation and modification dates.

  Mainly for use in examples, text from marker
  \samp{> ## IGNORE_RDIFF_BEGIN} up to (but not including)
  \samp{> ## IGNORE_RDIFF_END} is ignored.
}
\value{
  If \code{Log} is true, a list with components \code{status} (see
  below) and \code{out}, a character vector of descriptions of
  differences, possibly of zero length.

  Otherwise, a status indicator, \code{0L} if and only if no differences
  were found.
}

\seealso{
  The shell script run as \command{R CMD Rdiff}.
}

\keyword{utilities}