merge incorporates all changes that lead from file2 to file3 into file1. The result ordinarily goes into file1. merge is useful for combining separate changes to an original. Suppose file2 is the original, and both file1 and file3 are modifications of file2. Then merge combines both changes.
A conflict occurs if both file1 and file3 have changes in a common segment of lines. If a conflict is found, merge normally outputs a warning and brackets the conflict with and lines. A typical conflict will look like this:
file A lines in file A ======= lines in file B file B
Output conflicts using the -A style of diff3(1), if supported by diff3. This merges all changes leading from file2 to file3 into file1, and generates the most verbose output.
These options specify conflict styles that generate less information than -A. See diff3(1) for details. The default is -E. With -e, merge does not warn about conflicts.
This option may be given up to three times, and specifies labels to be used in place of the corresponding file names in conflict reports. That is, merge -L x -L y -L z a b c generates output that looks like it came from files x, y and z instead of from files a, b and c.
Send results to standard output instead of overwriting file1.