cdif - word context diff


cdif [option] file1 file2

cdif [option] [diff-data]


        -c, -Cn         context diff
        -u, -Un         unified diff
        -i              ignore case
        -b              ignore space change
        -w              ignore whitespace
        -t              expand tabs
        --rcs           use rcsdiff
        -r<rev>, -q     rcs options

        --diff=command      specify diff command
        --subdiff=command   specify backend diff command
        --stat              show statistical information
        --colormap=s        specify color map
        --unit=s            word, char or mecab     (default word)
        --[no]color         color or not            (default true)
        --[no]256           ANSI 256 color mode     (default true)
        --[no]commandcolor  color for command line  (default true)
        --[no]markcolor     color for diff mark     (default true)
        --[no]textcolor     color for normal text   (default true)
        --[no]unknowncolor  color for unknown text  (default true)
        --[no]old           print old text          (default true)
        --[no]new           print new text          (default true)
        --[no]command       print diff command line (default true)
        --[no]unknown       print unknown line      (default true)
        --[no]mark          print mark or not       (default true)
        --[no]prefix        read git --graph output (default true)
        --prefix-pattern    prefix pattern
        --visible char=?    set visible attributes
        --[no]mecab         use mecab tokenizer     (default false)
        --[no]lenience      supress unexpected input warning (default true)


cdif is a post-processor of the Unix diff command. It highlights deleted, changed and added words based on word context.

You may want to compare character-by-character rather than word-by-word. Option -B option can be used for that purpose.

If only one file is specified, cdif reads that file (stdin if no file) as a output from diff command.

Lines those don't look like diff output are simply ignored and printed.



Almost same as diff command.

--rcs, -rrev, -q

Use rcsdiff instead of normal diff. Option --rcs is not required when -rrev is supplied.


Specify the comparing unit. Default is word and compare each line word-by-word. Specify char if you want to compare them character-by-character.

When mecab is given as an unit, mecab command is called as a tokenizer for non-ASCII text. ASCII text is compared word-by-word. External mecab command has to been installed.

-B, --char

Shortcut for --unit=char. This option is being deprecated, and will be removed in a future.


Shortcut for --unit=mecab.


Specify the diff command to use.


Specify the backend diff command to get word differences. Accept normal and unified diff format.

If you want to use git diff command, don't forget to set -U0 option.

    --subdiff="git diff -U0 --no-index --histogram"

Use ANSI color escape sequence for output.

--colormap=colormap, --cm=colormap

Basic colormap format is :


where the FIELD is one from these :

    COMMAND  Command line
    OMARK    Old mark
    NMARK    New mark
    OTEXT    Old text
    NTEXT    New text
    OCHANGE  Old change part
    NCHANGE  New change part
    APPEND   Appended part
    DELETE   Deleted part

and additional Common and Merged FIELDs for git-diff combined format.

    CMARK    Common mark
    CTEXT    Common text
    MMARK    Merged mark
    MTEXT    Merged text

You can make multiple fields same color joining them by = :


Also wildcard can be used for field name :


Multiple fields can be specified by repeating options

    --cm FILED1=COLOR1 --cm FIELD2=COLOR2 ...

or combined with comma (,) :

    --cm FILED1=COLOR1,FIELD2=COLOR2, ...

Color specification is a combination of single uppercase character representing 8 colors :

    R  Red
    G  Green
    B  Blue
    C  Cyan
    M  Magenta
    Y  Yellow
    K  Black
    W  White

and alternative (usually brighter) colors in lowercase :

    r, g, b, c, m, y, k, w

or RGB values and 24 grey levels if using ANSI 256 or full color terminal :

    (255,255,255)      : 24bit decimal RGB colors
    #000000 .. #FFFFFF : 24bit hex RGB colors
    #000    .. #FFF    : 12bit hex RGB 4096 colors
    000 .. 555         : 6x6x6 RGB 216 colors
    L00 .. L25         : Black (L00), 24 grey levels, White (L25)

or color names enclosed by angle bracket :

    <red> <blue> <green> <cyan> <magenta> <yellow>
    <aliceblue> <honeydue> <hotpink> <mooccasin>

with other special effects :

    D  Double-struck (boldface)
    I  Italic
    U  Underline
    S  Stand-out (reverse video)

Above color spec is simplified summary so if you want complete information, read Getopt::EX::Colormap.

Defaults are :

    COMMAND => "555/222E"
    OMARK   => "CS"
    NMARK   => "MS"
    OTEXT   => "C"
    NTEXT   => "M"
    OCHANGE => "K/445"
    NCHANGE => "K/445"
    DELETE  => "K/544"
    APPEND  => "K/544"

    CMARK   => "GS"
    MMARK   => "YS"
    CTEXT   => "G"
    MTEXT   => "Y"

This is equivalent to :

    cdif --cm 'COMMAND=555/222E,OMARK=CS,NMARK=MS' \
         --cm 'OTEXT=C,NTEXT=M,*CHANGE=BD/445,DELETE=APPEND=RD/544' \
--[no]commandcolor, --cc
--[no]markcolor, --mc
--[no]textcolor, --tc
--[no]unknowncolor, --uc

Enable/Disable using color for the corresponding field.

--[no]old, --[no]new

Print or not old/new text in diff output.


Print or not command lines preceding diff output.


Print or not lines not look like diff output.


Print or not marks at the top of diff output lines. At this point, this option is effective only for unified diff.

Next example produces the output exactly same as new except visual effects.

    cdif -U100 --no-mark --no-old --no-command --no-unknown old new

These options are prepared for watchdiff(1) command.


Understand prefix for diff output including git --graph option. True by default.


Specify prefix pattern in regex. Default pattern is:

    (?:\| )*(?:  )*

This pattern matches git graph style and whitespace indented diff output.

--visible chaname=[0,1]

Set visible attribute for specified characters. Default visible: nul, bel, bs, vt, np, cr, esc, del. Default invisible: ht, nl, sp. See ascii(7) for name representation.

Multiple characters can be specified at once, by assembling them by commna (,) like --visible ht=1,sp=1; or connecting them by equal sign (=) like --visible ht=sp=1. Character name accept wildcard; --visible '*=1'.

Currently this option is effective only for modified lines.


Set CARRIAGE-RETURN and ESCAPE visible attributes. These options will be deprecated soon. Use --visible option instead.


Print statistical information at the end of output. It shows number of total appended/deleted/changed words in the context of cdif. It's common to have many insertions and deletions of newlines because of text filling process. So normal information is followed by modified number which ignores insert/delete newlines.


Supress warning message for unexpected input from diff command. True by default.


Environment variable CDIFOPTS is used to set default options.


Kazumasa Utashiro


Copyright 1992-2020 Kazumasa Utashiro

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.


sdif(1), watchdiff(1)



cdif is naturally not very fast because it uses normal diff command as a back-end processor to compare words.