gdiffmk(1) General Commands Manual gdiffmk(1) Name gdiffmk - mark differences between groff/nroff/troff files Synopsis gdiffmk [-a add-mark] [-c change-mark] [-d delete-mark] [-x diff-command] [-D [-B] [-M mark1 mark2]] [--] file1 file2 [output-file] gdiffmk --help gdiffmk --version Description gdiffmk compares two roff(7) documents, file1 and file2, and writes an- other, derived from both, to the standard output stream (or output-file), adding margin character (mc) requests at places in the output where the in- put documents differ. gdiffmk does not interpret the source documents; it treats roff comments and nilpotent changes to formatting as meaningful. For example, it does not know that \h'3m', \h'(1 * 3m)', and \h'3m+0' all mean the same thing. If the file1 or file2 argument is "-", gdiffmk reads the standard input stream for that input. If the output operand is present, gdiffmk writes output to a file of that name. If it is "-" or ab- sent, gdiffmk writes output to the standard output stream. "-" cannot be both an input and output operand. Options --help displays a usage message and --version shows version information; both exit afterward. -a add-mark Annotate material absent from file1 but present in file2 with add- mark (default: "+"). -B Suppress br requests normally inserted by -D option. Use with cau- tion; such requests are the only way to guarantee that deletions and small changes are marked. -c change-mark Annotate material differing between file1 and file2 with change-mark (default: "|"). -d delete-mark Annotate material present in file1 but absent from file2 with delete-mark (default: "*"). -D Mark changed and deleted material with surrounding delimiters. -M mark1 mark2 Use mark1 (default: "[[") and mark2 (default: "]]") as delimiters when using the -D option. -x diff-command Use the diff-command program to perform the comparison of file1 and file2. diff-command (default: diff) must accept GNU diff(1)'s -D extension option. -- Treat all subsequent arguments as file names, even if they begin with "-". Exit status gdiffmk exits with status 0 if the input files are the same; 1 if they dif- fer; 2 upon a usage error; 3 if the system's diff(1) or sh(1) commands do not support features gdiffmk requires; and 4 if the output argument is a duplicate of file1 or file2. Caveats The output is not necessarily compatible with all macro packages or pre- processors. A reliable workaround is to run gdiffmk on the output of the final preprocessor instead of the input source. gdiffmk relies on the -D option of GNU diff to make a merged "#ifdef" out- put format. Busybox diff is known to not support it. Also see the -x diff-command option. Authors gdiffmk was written by Mike Bianchi, now retired. It is maintained by the groff developers. See also groff(1), nroff(1), troff(1), roff(7), diff(1) groff 1.24.1 2026-03-14 gdiffmk(1)
Name | Synopsis | Description | Options | Exit status | Caveats | Authors | See also
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