diff3 - 3-way differential file comparison
diff3 [ -exEX3 [-i | -m] [-L label1 -L label3] ] file1 file2 file3
Diff3 compares three versions of a file, and publishes disagreeing ranges
of text flagged with these codes:
==== all three files differ
====1 file1 is different
====2 file2 is different
====3 file3 is different
The type of change suffered in converting a given range of a given file
to some other is indicated in one of these ways:
f : n1 a Text is to be appended after line number n1 in file f,
where f = 1, 2, or 3.
f : n1 , n2 c Text is to be changed in the range line n1 to line n2.
If n1 = n2, the range may be abbreviated to n1.
The original contents of the range follows immediately after a c
indication. When the contents of two files are identical, the contents
of the lower-numbered file is suppressed.
The -m option produces a merge script on the output of diff3. If none of
-eExX3 is specified along with -m, then the format of option -E is
presumed. If the -m option is used, then binary files, files without
trailing newline, and files with excessively long lines can be
If no -m option is specified, then under the -e option, diff3 publishes a
script for the editor ed(1) that will incorporate into file1 all changes
between file2 and file3, i.e. the changes that normally would be flagged
==== and ====3. Option -x (-3) produces a script to incorporate only
changes flagged ==== (====3). The following command will apply the
resulting script to `file1', and emit the result on the output stream.
(cat script; echo '1,$p') | ed - file1
The -E and -X are similar to -e and -x, respectively, but treat
overlapping changes (i.e., changes that would be flagged with ==== in the
normal listing) differently. The overlapping lines from both files will
be inserted by the edit script, bracketed by "<<<<<<" and ">>>>>>" lines.
For example, suppose lines 7-8 are changed in both file1 and file3. The
merged output of the command
"diff3 -m file1 file2 file3"
lines 1-6 of file1
lines 7-8 of file1
lines 7-8 of file3
rest of file1
If there are overlaps, the user should edit the result and delete one of
the alternatives. If the -L label1 and -L label3 options are given, the
labels are output in place of the names file1 and file3 in overlap
If the option -i is specified along with one of the options -exEX3, then
the resulting edit script has the editor commands
added at the end. Then the following command will update `file1' in
place with the changes.
ed - file1 < script
If merges are done by generating explicit scripts to input to the editor,
rather than by using the -m option, the merge is limited by the
capabilities of the editor ed(1). The editor cannot handle excessively
long lines, binary files (with nul bytes) or files without a trailing
An exit status of 0 means diff3 was successful, 1 means some overlaps
were found, and 2 means trouble.
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