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Manual Pages  — DIFF


diff - compare files line by line



diff [OPTION]... FILES


Compare files line by line.
-i --ignore-case
  Ignore case differences in file contents.
  Ignore case when comparing file names.
  Consider case when comparing file names.
-E --ignore-tab-expansion
  Ignore changes due to tab expansion.
-b --ignore-space-change
  Ignore changes in the amount of white space.
-w --ignore-all-space
  Ignore all white space.
-B --ignore-blank-lines
  Ignore changes whose lines are all blank.
-I RE --ignore-matching-lines=RE
  Ignore changes whose lines all match RE.
  Strip trailing carriage return on input.
-a --text Treat all files as text.
-c -C NUM --context[=NUM]
  Output NUM (default 3) lines of copied context.
-u -U NUM --unified[=NUM]
  Output NUM (default 3) lines of unified context.
--label LABEL
  Use LABEL instead of file name.
-p --show-c-function
  Show which C function each change is in.
-F RE --show-function-line=RE
  Show the most recent line matching RE.
-q --brief
  Output only whether files differ.
-e --ed Output an ed script.
  Output a normal diff.
-n --rcs Output an RCS format diff.
-y --side-by-side
  Output in two columns.
-W NUM --width=NUM
  Output at most NUM (default 130) print columns.
  Output only the left column of common lines.
  Do not output common lines.
-D NAME --ifdef=NAME
  Output merged file to show `#ifdef NAME' diffs.
  Similar, but format GTYPE input groups with GFMT.
  Similar, but format all input lines with LFMT.
  Similar, but format LTYPE input lines with LFMT.
LTYPE is `old', `new', or `unchanged'.
  GTYPE is LTYPE or `changed'.
GFMT may contain:
%< lines from FILE1
%> lines from FILE2
%= lines common to FILE1 and FILE2
  printf-style spec for LETTER
LETTERs are as follows for new group, lower case for old group:
F first line number
L last line number
N number of lines = L-F+1
E F-1
M L+1
LFMT may contain:
%L contents of line
%l contents of line, excluding any trailing newline
  printf-style spec for input line number
Either GFMT or LFMT may contain:
%% %
%c'C' the single character C
%c'\OOO' the character with octal code OOO
-l --paginate
  Pass the output through `pr' to paginate it.
-t --expand-tabs
  Expand tabs to spaces in output.
-T --initial-tab
  Make tabs line up by prepending a tab.
  Tab stops are every NUM (default 8) print columns.
-r --recursive
  Recursively compare any subdirectories found.
-N --new-file
  Treat absent files as empty.
  Treat absent first files as empty.
-s --report-identical-files
  Report when two files are the same.
-x PAT --exclude=PAT
  Exclude files that match PAT.
-X FILE --exclude-from=FILE
  Exclude files that match any pattern in FILE.
-S FILE --starting-file=FILE
  Start with FILE when comparing directories.
  Compare FILE1 to all operands. FILE1 can be a directory.
  Compare all operands to FILE2. FILE2 can be a directory.
  Keep NUM lines of the common prefix and suffix.
-d --minimal
  Try hard to find a smaller set of changes.
  Assume large files and many scattered small changes.
-v --version
  Output version info.
--help Output this help.
FILES are `FILE1 FILE2' or `DIR1 DIR2' or `DIR FILE...' or `FILE... DIR'. If --from-file or --to-file is given, there are no restrictions on FILES. If a FILE is `-', read standard input. Exit status is 0 if inputs are the same, 1 if different, 2 if trouble.


Written by Paul Eggert, Mike Haertel, David Hayes, Richard Stallman, and Len Tower.


Report bugs to <bug-gnu-utils@gnu.org>.


Copyright © 2004 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


The full documentation for diff is maintained as a Texinfo manual. If the info and diff programs are properly installed at your site, the command
info diff

April 2004 DIFF (1) diffutils 2.8.7

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This philosophy, in the hands of amateurs, leads to inexplicably mind-numbing botches like the existence of two programs, “head” and “tail,” which print the first part or the last part of a file, depending. Even though their operations are duals of one another, “head” and “tail” are different programs, written by different authors, and take different options!
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