DIFF(1)                              SysV                              DIFF(1)



NAME
     diff - differential file comparator

SYNOPSIS
     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 used to convert file1 into file2.  The
     numbers after the letters pertain to file2.  In fact, by using a instead
     of d and reading backward, you can see 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 >.

OPTIONS
     -b   Causes trailing blanks (spaces and tabs) to be ignored and other
          strings of blanks to compare equal.

     -e   Produces a script of a, c, and d commands for the editor ed, which
          recreates file2 from file1.

     -f   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 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.

     -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.

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

WARNINGS
     Missing newline at end of file X
     indicates that the last line of file X did not have a new-line.  If the
     lines are different, they will be flagged and output; although the output
     will seem to indicate they are the same.

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

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

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