32v 1m diff

DIFF(1) UNIX Programmer's Manual DIFF(1)

NAME

    diff - differential file comparator

SYNOPSIS

    diff [ -efbh ] file1 file2

DESCRIPTION

    _D_i_f_f tells what lines must be changed in two files to bring
    them into agreement.  If _f_i_l_e_1 (_f_i_l_e_2) is `-', the standard
    input is used.  If _f_i_l_e_1 (_f_i_l_e_2) is a directory, then a file
    in that directory whose file-name is the same as the file-
    name of _f_i_l_e_2 (_f_i_l_e_1) is used.  The normal output contains
    lines of these forms:

         _n_1 a _n_3,_n_4
         _n_1,_n_2 d _n_3
         _n_1,_n_2 c _n_3,_n_4

    These lines resemble _e_d commands to convert _f_i_l_e_1 into
    _f_i_l_e_2.  The numbers after the letters pertain to _f_i_l_e_2.  In
    fact, by exchanging `a' for `d' and reading backward one may
    ascertain equally how to convert _f_i_l_e_2 into _f_i_l_e_1.  As in
    _e_d, identical pairs where _n_1 = _n_2 or _n_3 = _n_4 are abbreviated
    as a single number.

    Following each of these lines come all the lines that are
    affected in the first file flagged by `<', then all the
    lines that are affected in the second file flagged by `>'.

    The -b option causes trailing blanks (spaces and tabs) to be
    ignored and other strings of blanks to compare equal.

    The -e option produces a script of _a, _c and _d commands for
    the editor _e_d, which will recreate _f_i_l_e_2 from _f_i_l_e_1.  The -f
    option produces a similar script, not useful with _e_d, in the
    opposite order.  In connection with -e, the following shell
    program may help maintain multiple versions of a file.  Only
    an ancestral file ($1) and a chain of version-to-version _e_d
    scripts ($2,$3,...) made by _d_i_f_f need be on hand.  A `latest
    version' appears on the standard output.

         (shift; cat $*; echo '1,$p') | ed - $1

    Except in rare circumstances, _d_i_f_f finds a smallest suffi-
    cient set of file differences.

    Option -h does a fast, half-hearted job.  It works only when
    changed stretches are short and well separated, but does
    work on files of unlimited length.  Options -e and -f are
    unavailable with -h.

FILES

    /tmp/d?????
    /usr/lib/diffh for -h

SEE ALSO

    cmp(1), comm(1), ed(1)

DIAGNOSTICS

    Exit status is 0 for no differences, 1 for some, 2 for trou-
    ble.

BUGS

    Editing scripts produced under the -e or -f option are naive
    about creating lines consisting of a single `.'.