


      DIFF(1)                     (UNIX 5.0)                    DIFF(1)



      NAME
           diff - differential file comparator

      SYNTAX
           diff [ -efbh ] file1 file2

      DESCRIPTION
           Diff tells what lines must be changed in two files to bring
           them into agreement.  If file1 (file2) is -, the standard
           input is used.  If file1 (file2) is a directory, then a file
           in that directory with the name file2 (file1) is used.  The
           normal output contains lines of these forms:

                n1 a n3,n4
                n1,n2 d n3
                n1,n2 c n3,n4

           These lines resemble ed commands to convert file1 into
           file2.  The numbers after the letters pertain to file2.  In
           fact, by exchanging a for d and reading backward one may
           ascertain equally how to convert file2 into file1.  As in
           ed, identical pairs where n1 = n2 or n3 = n4 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 ed, which will recreate file2 from file1.  The -f
           option produces a similar script, not useful with ed, 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 ed
           scripts ($2,$3,...) made by diff need be on hand.  A
           ``latest version'' appears on the standard output.

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

           Except in rare circumstances, diff finds a smallest
           sufficient 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?????



      Page 1                                          (73 A2 02MT REV1)






      DIFF(1)                     (UNIX 5.0)                    DIFF(1)



           /usr/lib/diffh for -h

      SEE ALSO
           cmp(1), comm(1), ed(1).

      DIAGNOSTICS
           Exit status is 0 for no differences, 1 for some differences,
           2 for trouble.

      BUGS
           Editing scripts produced under the -e or -f option are naive
           about creating lines consisting of a single period (.).











































      Page 2                                          (73 A2 02MT REV1)



