DIFFMK(1)               COMMAND REFERENCE               DIFFMK(1)



NAME
     diffmk - mark differences between files

SYNOPSIS
     diffmk name1 name2 [ name3 ]

DESCRIPTION
     Diffmk compares two versions of a file and creates a third
     file that includes ``change mark'' commands for nroff.
     Name1 and name2 are the old and new versions of the file.
     name2 may be given as '-', which will cause diffmk to read
     from the standard input.  name1 may not be specified as '-'.
     Diffmk generates name3, if it exists, which contains the
     lines of name2 plus inserted formatter ``change mark'' (.mc)
     requests.  If name3 was not specified the result is placed
     on standard out.  When name3 is formatted, changed or
     inserted text is shown by | at the right margin of each
     line.  The position of deleted text is shown by a single *.

     If anyone is so inclined, diffmk can be used to produce
     listings of C (or other) programs with changes marked.  A
     typical command line for such use is:

          diffmk old.c new.c > diff.nr
          nroff macs diff.nr

     where the file macs contains:

          .pl 1
          .ll 77
          .nf
          .eo
          .nc `

     The .ll request might specify a different line length,
     depending on the nature of the program being printed.  The
     .eo and .nc requests are probably needed only for C
     programs.

     If the characters | and * are inappropriate, a copy of
     diffmk can be edited to change them (diffmk is a shell
     procedure).

EXAMPLES
     The following example generates a file changes which
     contains the differences between source.nr and newsource.nr
     marked with change bars.

          diffmk source.nr newsource.nr diff.nr
          nroff diff.nr > changes





Printed 4/6/89                                                  1

DIFFMK(1)               COMMAND REFERENCE               DIFFMK(1)



RETURN VALUE
     [NO_ERRS]      Command completed without error.

     [USAGE]        Incorrect command line syntax. Execution
                    terminated.

     [NP_ERR]       An error occurred that was not a system
                    error.  Execution terminated.

CAVEATS
     The input files are expected to be nroff(1) input. Other
     types of input, including formatted text, require special
     macros similar to those required for C source.

     Incorrect output may be generated when diffmk is used at the
     beginning of a pipe.  It is therefore recommended that the
     output from diffmk be put in a file before formatting.

     Aesthetic considerations may dictate manual adjustment of
     some output.  File differences involving only formatting
     requests may produce undesirable output, i.e., replacing .sp
     by .sp 2 will produce a ``change mark'' on the preceding or
     following line of output.

SEE ALSO
     diff(1) and nroff(1).





























Printed 4/6/89                                                  2

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