DIFF(1)

NAME
diff - compare files line by line

SYNOPSIS
diff [OPTION]... FILES

DESCRIPTION
Compare FILES line by line.

Mandatory arguments to long options are mandatory for short options too.

--normal
    output a normal diff (the default)

-q, --brief
    report only when files differ

-s, --report-identical-files
    report when two files are the same

-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

-e, --ed
    output an ed script

-n, --rcs
    output an RCS format diff

-y, --side-by-side
    output in two columns

-W, --width=NUM
    output at most NUM (default 130) print columns

--left-column
    output only the left column of common lines

--suppress-common-lines
    do not output common lines

-p, --show-c-function
    show which C function each change is in

-F, --show-function-line=RE
    show the most recent line matching RE

--label LABEL
    use LABEL instead of file name and timestamp (can be repeated)

-t, --expand-tabs
    expand tabs to spaces in output

-T, --initial-tab
    make tabs line up by prepending a tab

--tabsize=NUM
    tab stops every NUM (default 8) print columns

--suppress-blank-empty
    suppress space or tab before empty output lines

-l, --paginate
    pass output through 'pr' to paginate it

-r, --recursive
    recursively compare any subdirectories found

--no-dereference
    don't follow symbolic links

-N, --new-file
    treat absent files as empty

--unidirectional-new-file
    treat absent first files as empty

--ignore-file-name-case
    ignore case when comparing file names

--no-ignore-file-name-case
    consider case when comparing file names

-x, --exclude=PAT
    exclude files that match PAT

-X, --exclude-from=FILE
    exclude files that match any pattern in FILE

-S, --starting-file=FILE
    start with FILE when comparing directories

--from-file=FILE1
    compare FILE1 to all operands; FILE1 can be a directory

--to-file=FILE2
    compare all operands to FILE2; FILE2 can be a directory

-i, --ignore-case
    ignore case differences in file contents

-E, --ignore-tab-expansion
    ignore changes due to tab expansion

-Z, --ignore-trailing-space
    ignore white space at line end

-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 where lines are all blank

-I, --ignore-matching-lines=RE
    ignore changes where all lines match RE

-a, --text
    treat all files as text

--strip-trailing-cr
    strip trailing carriage return on input

-D, --ifdef=NAME
    output merged file with '#ifdef NAME' diffs

--GTYPE-group-format=GFMT
    format GTYPE input groups with GFMT

--line-format=LFMT
    format all input lines with LFMT

--LTYPE-line-format=LFMT
    format LTYPE input lines with LFMT

    These format options provide fine-grained control over the output

    of diff, generalizing -D/--ifdef.

LTYPE is 'old', 'new', or 'unchanged'.
    GTYPE is LTYPE or 'changed'.

    GFMT (only) may contain:

%<  lines from FILE1

%>  lines from FILE2

%=  lines common to FILE1 and FILE2

%[-][WIDTH][.[PREC]]{doxX}LETTER
    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

%(A=B?T:E)
    if A equals B then T else E

    LFMT (only) may contain:

%L  contents of line

%l  contents of line, excluding any trailing newline

%[-][WIDTH][.[PREC]]{doxX}n
    printf-style spec for input line number

    Both GFMT and LFMT may contain:

%%  %

%c'C'
    the single character C

%c'\OOO'
    the character with octal code OOO

C   the character C (other characters represent themselves)

-d, --minimal
    try hard to find a smaller set of changes

--horizon-lines=NUM
    keep NUM lines of the common prefix and suffix

--speed-large-files
    assume large files and many scattered small changes

--color[=WHEN]
    color output; WHEN is 'never', 'always', or 'auto'; plain --color means --color='auto'

--palette=PALETTE
    the colors to use when --color is active; PALETTE is a colon-separated list of terminfo capabilities

--help
    display this help and exit

-v, --version
    output version information and exit

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 FILE(s). If a FILE is '-', read standard input. Exit status is 0 if inputs are the same, 1 if different, 2 if trouble.

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

REPORTING BUGS
Report bugs to: bug-diffutils@gnu.org
GNU diffutils home page: <https://www.gnu.org/software/diffutils/>
General help using GNU software: <https://www.gnu.org/gethelp/>

COPYRIGHT
Copyright © 2025 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.

SEE ALSO
wdiff(1), cmp(1), diff3(1), sdiff(1), patch(1)

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

should give you access to the complete manual.