diffmk(1)

DESCRIPTION

diffmk compares the previous version of a file with the current version and creates a file that includes nroff/troff ``change mark'' commands. prevfile is the name of the previous version of the file and currfile is the name of the current version of the file. diffmk generates markfile which contains all the lines of the currfile plus inserted formatter ``change mark'' (.mc) requests. When markfile is formatted, changed or inserted text is shown by a | character at the right margin of each line. The position of deleted text is shown by a single *.

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

EXTERNAL INFLUENCES

EXAMPLES

A typical command line for comparing two versions of an nroff/troff file and generating a file with the changes marked is:

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

where the file macs contains:

The .ll request can specify a different line length, depending on the nature of the program being printed. The .eo request is probably needed only for C programs.

WARNINGS

Aesthetic considerations may dictate manual adjustment of some output.

diffmk does not differentiate between changes in text and changes in formatter request coding. Thus, file differences involving only formatting changes (such as replacing .sp with .sp 2 in a text source file) with no change in actual text can produce change marks.

Although unlikely, certain combinations of formatting requests can cause change marks to either disappear or to mark too much. Manual intervention may be required because the subtleties of various formatting macro packages and preprocessors is beyond the scope of diffmk. tbl cannot tolerate .mc commands in its input (see tbl(1)), so any .mc request that would appear inside a .TS range is silently deleted. The script can be changed if this action is inappropriate, or diffmk can be run on two files that have both been run through the tbl preprocessor before any comparisons are made.

diffmk uses diff, and thus has the same limitations on file size and performance that diff may impose (see diff(1)). In particular the performance is nonlinear with the size of the file, and very large files (well over 1000 lines) may take extremely long to process. Breaking the file into smaller pieces may be advisable.

diffmk also uses the ed(1) editor. If the file is too large for ed, ed error messages may be embedded in the file. Again, breaking the file into smaller pieces may be advisable.

SEE ALSO

diff(1), nroff(1).