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

NAME
     diff - differential file and directory comparator

SYNOPSIS
     diff [ -l ] [ -r ] [ -s ] [ -cefh ] [ -b ] dir1 dir2
     diff [ -cefh ] [ -b ] file1 file2
     diff [ -D_s_t_r_i_n_g ] [ -b ] file1 file2

DESCRIPTION
     If both arguments are directories, _d_i_f_f sorts the contents
     of the directories by name, and then runs the regular file
     _d_i_f_f algorithm (described below) on text files which are
     different.  Binary files which differ, common subdirec-
     tories, and files which appear in only one directory are
     listed.  Options when comparing directories are:

     -l   long output format; each text file _d_i_f_f is piped
          through _p_r(1) to paginate it, other differences are
          remembered and summarized after all text file differ-
          ences are reported.

     -r   causes application of _d_i_f_f recursively to common sub-
          directories encountered.

     -s   causes _d_i_f_f to report files which are the same, which
          are otherwise not mentioned.

     -Sname
          starts a directory _d_i_f_f in the middle beginning with
          file _n_a_m_e.

     When run on regular files, and when comparing text files
     which differ during directory comparison, _d_i_f_f tells what
     lines must be changed in the files to bring them into agree-
     ment.  Except in rare circumstances, _d_i_f_f finds a smallest
     sufficient set of file differences.  If neither _f_i_l_e_1 nor
     _f_i_l_e_2 is a directory, then either may be given as `-', in
     which case the standard input is used.  If _f_i_l_e_1 is a direc-
     tory, then a file in that directory whose file-name is the
     same as the file-name of _f_i_l_e_2 is used (and vice versa).

     There are several options for output format; the default
     output format 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

Printed 7/25/83                                                 1

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

     _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 `>'.

     Except for -b, which may be given with any of the others,
     the following options are mutually exclusive:

     -e       producing a script of _a, _c and _d commands for the
              editor _e_d, which will recrea