The diff3(1) utility compares the contents of three
different versions of a file, file1, file2 and
file3, writing the result to the standard output. The
options describe different methods of merging and purging the
separate versions into a new file. The diff3(1) utility is
used by the RCS commands to merge specific versions or create new
versions.
Produce output in a form suitable as an input script for the
ed(1) utility. The script CAN then be used to merge
differences common between all three files and differences specific
to file1 and file3. In other words, the -e
option ignores differences specific to file1 and
file2, and those specific to file2 and file3.
It is useful for backing out changes specific to file2
only.
-x
Produce an output script suitable for ed(1) with changes
specific only to all three versions.
-3
Produce an output script suitable for ed(1) with changes
specific only to file3.
-E
Similar to -e but treat overlapping changes (that is,
changes that would be noted with ==== in the normal listing)
differently. The overlapping lines from both files will be inserted
by the edit script, bracketed by "<<<<<<" and
">>>>>>" lines.
-X
Similar to -x, but treat overlapping changes (as
described for -E) differently. The overlapping lines from
both files will be inserted by the edit script, bracketed by
"<<<<<<" and ">>>>>>"
lines.
The -E option is used by RCS merge(1) to ensure
that overlapping changes in the merged files are preserved and are
therefore noticeable.
For example, suppose lines 7-8 are changed in both file1
and file2. Applying to file1 the edit script
generated by the following command:
diff3 -E file1 file2 file3
results in the file:
lines 1-6
of file1
<<<<<<< file1
lines 7-8
of file1
=======
lines 7-8
of file3
>>>>>>> file3
rest of file1
The default output of diff3(1) makes notation of the
differences between all files, as well as those differences
specific to each pair of files. The changes are described by the
commands necessary for ed(1) to create the desired target
from the different versions. See diff(1) for a description
of the commands.
====
The lines beneath this notation are ranges of lines that are
different between all files.
====n
The lines beneath this notation are ranges of lines that are
exclusively different in file n.
The -e option cannot detect and change lines that have a
period (.) as the first and only character on the line. The
resulting script fails on that line because . is an
ed(1) editing command.