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RedHat 9 (Linux i386) - man page for diff (redhat section 1)

DIFF(1) 				    GNU Tools					  DIFF(1)

NAME
       diff - find differences between two files

SYNOPSIS
       diff [options] from-file to-file

DESCRIPTION
       In  the	simplest case, diff compares the contents of the two files from-file and to-file.
       A file name of - stands for text read from the standard input.  As a special case, diff	-
       - compares a copy of standard input to itself.

       If  from-file is a directory and to-file is not, diff compares the file in from-file whose
       file name is that of to-file, and vice versa.  The non-directory file must not be -.

       If both from-file and to-file are directories, diff compares corresponding files  in  both
       directories,  in  alphabetical  order;  this  comparison is not recursive unless the -r or
       --recursive option is given.  diff never compares the actual contents of a directory as if
       it were a file.	The file that is fully specified may not be standard input, because stan-
       dard input is nameless and the notion of ``file with the same name'' does not apply.

       diff options begin with -, so normally from-file and to-file may not begin with	-.   How-
       ever,  --  as  an  argument by itself treats the remaining arguments as file names even if
       they begin with -.

   Options
       Below is a summary of all of the options that GNU diff accepts.	 Most  options	have  two
       equivalent names, one of which is a single letter preceded by -, and the other of which is
       a long name preceded by --.  Multiple single letter options (unless they take an argument)
       can  be	combined into a single command line word: -ac is equivalent to -a -c.  Long named
       options can be abbreviated to any unique prefix of their name.  Brackets ([ and	])  indi-
       cate that an option takes an optional argument.

       -lines Show  lines  (an integer) lines of context.  This option does not specify an output
	      format by itself; it has no effect unless it is  combined  with  -c  or  -u.   This
	      option is obsolete.  For proper operation, patch typically needs at least two lines
	      of context.

       -a     Treat all files as text and compare them line-by-line, even if they do not seem  to
	      be text.

       -b     Ignore changes in amount of white space.

       -B     Ignore changes that just insert or delete blank lines.

       --brief
	      Report only whether the files differ, not the details of the differences.

       -c     Use the context output format.

       -C lines
       --context[=lines]
	      Use  the	context  output  format,  showing lines (an integer) lines of context, or
	      three if lines is not given.  For proper operation, patch typically needs at  least
	      two lines of context.

       --changed-group-format=format
	      Use format to output a line group containing differing lines from both files in if-
	      then-else format.

       -d     Change the algorithm to perhaps find a smaller set of  changes.	This  makes  diff
	      slower (sometimes much slower).

       -D name
	      Make merged if-then-else format output, conditional on the preprocessor macro name.

       -e
       --ed   Make output that is a valid ed script.

       --exclude=pattern
	      When  comparing  directories, ignore files and subdirectories whose basenames match
	      pattern.

       --exclude-from=file
	      When comparing directories, ignore files and subdirectories whose  basenames  match
	      any pattern contained in file.

       --expand-tabs
	      Expand tabs to spaces in the output, to preserve the alignment of tabs in the input
	      files.

       -f     Make output that looks vaguely like an ed script but has changes in the order  they
	      appear in the file.

       -F regexp
	      In  context and unified format, for each hunk of differences, show some of the last
	      preceding line that matches regexp.

       --forward-ed
	      Make output that looks vaguely like an ed script but has changes in the order  they
	      appear in the file.

       -h     This option currently has no effect; it is present for Unix compatibility.

       -H     Use  heuristics to speed handling of large files that have numerous scattered small
	      changes.

       --horizon-lines=lines
	      Do not discard the last lines lines of the common prefix and the first lines  lines
	      of the common suffix.

       -i     Ignore changes in case; consider upper- and lower-case letters equivalent.

       -I regexp
	      Ignore changes that just insert or delete lines that match regexp.

       --ifdef=name
	      Make merged if-then-else format output, conditional on the preprocessor macro name.

       --ignore-all-space
	      Ignore white space when comparing lines.

       --ignore-blank-lines
	      Ignore changes that just insert or delete blank lines.

       --ignore-case
	      Ignore changes in case; consider upper- and lower-case to be the same.

       --ignore-matching-lines=regexp
	      Ignore changes that just insert or delete lines that match regexp.

       --ignore-space-change
	      Ignore changes in amount of white space.

       --initial-tab
	      Output  a  tab  rather  than a space before the text of a line in normal or context
	      format.  This causes the alignment of tabs in the line to look normal.

       -l     Pass the output through pr to paginate it.

       -L label
       --label=label
	      Use label instead of the file name in the context format and unified  format  head-
	      ers.

       --left-column
	      Print only the left column of two common lines in side by side format.

       --line-format=format
	      Use format to output all input lines in in-then-else format.

       --minimal
	      Change  the  algorithm  to  perhaps find a smaller set of changes.  This makes diff
	      slower (sometimes much slower).

       -n     Output RCS-format diffs; like -f except that each command specifies the  number  of
	      lines affected.

       -N
       --new-file
	      In  directory  comparison,  if  a  file is found in only one directory, treat it as
	      present but empty in the other directory.

       --new-group-format=format
	      Use format to output a group of lines taken from just the second file  in  if-then-
	      else format.

       --new-line-format=format
	      Use format to output a line taken from just the second file in if-then-else format.

       --old-group-format=format
	      Use  format  to  output a group of lines taken from just the first file in if-then-
	      else format.

       --old-line-format=format
	      Use format to output a line taken from just the first file in if-then-else format.

       -p     Show which C function each change is in.

       -P     When comparing directories, if a file appears only in the second directory  of  the
	      two, treat it as present but empty in the other.

       --paginate
	      Pass the output through pr to paginate it.

       -q     Report only whether the files differ, not the details of the differences.

       -r     When comparing directories, recursively compare any subdirectories found.

       --rcs  Output  RCS-format  diffs; like -f except that each command specifies the number of
	      lines affected.

       --recursive
	      When comparing directories, recursively compare any subdirectories found.

       --report-identical-files
       -s     Report when two files are the same.

       -S file
	      When comparing directories, start with the file file.  This is used for resuming an
	      aborted comparison.

       --from-file=file
	      Compare file to all operands.  file can be a directory.

       --to-file=file
	      Compare all operands to file. file can be a directory.

       --sdiff-merge-assist
	      Print  extra  information to help sdiff.	sdiff uses this option when it runs diff.
	      This option is not intended for users to use directly.

       --show-c-function
	      Show which C function each change is in.

       --show-function-line=regexp
	      In context and unified format, for each hunk of differences, show some of the  last
	      preceding line that matches regexp.

       --side-by-side
	      Use the side by side output format.

       --speed-large-files
	      Use  heuristics to speed handling of large files that have numerous scattered small
	      changes.

       --starting-file=file
	      When comparing directories, start with the file file.  This is used for resuming an
	      aborted comparison.

       --suppress-common-lines
	      Do not print common lines in side by side format.

       -t     Expand tabs to spaces in the output, to preserve the alignment of tabs in the input
	      files.

       -T     Output a tab rather than a space before the text of a line  in  normal  or  context
	      format.  This causes the alignment of tabs in the line to look normal.

       --text Treat  all  files as text and compare them line-by-line, even if they do not appear
	      to be text.

       -u     Use the unified output format.

       --unchanged-group-format=format
	      Use format to output a group of common lines taken from both files in  if-then-else
	      format.

       --unchanged-line-format=format
	      Use format to output a line common to both files in if-then-else format.

       --unidirectional-new-file
	      When  comparing  directories, if a file appears only in the second directory of the
	      two, treat it as present but empty in the other.

       -U lines
       --unified[=lines]
	      Use the unified output format, showing lines (an	integer)  lines  of  context,  or
	      three  if lines is not given.  For proper operation, patch typically needs at least
	      two lines of context.

       -v
       --version
	      Output the version number of diff.

       -w     Ignore white space when comparing lines.

       -W columns
       --width=columns
	      Use an output width of columns in side by side format.

       -x pattern
	      When comparing directories, ignore files and subdirectories whose  basenames  match
	      pattern.

       -X file
	      When  comparing  directories, ignore files and subdirectories whose basenames match
	      any pattern contained in file.

       -y     Use the side by side output format.

SEE ALSO
       cmp(1), comm(1), diff3(1), ed(1), patch(1), pr(1), sdiff(1).

DIAGNOSTICS
       An exit status of 0 means no differences were found, 1 means some differences were  found,
       and 2 means trouble.

GNU Tools				    22sep1993					  DIFF(1)


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