Comparing and Merging Files
10.4 Creating and Removing Files
Sometimes when comparing two directories, a file may exist in one
directory but not the other. If you give
`-N' or `--new-file' option, or if you supply an old or
new file that is named `/dev/null' or is empty and is dated the
Epoch (1970-01-01 00:00:00 UTC),
diff outputs a patch that
adds or deletes the contents of this file. When given such a patch,
patch normally creates a new file or removes the old file.
However, when conforming to POSIX (see section 10.12
patch and the POSIX Standard),
patch does not remove the old file, but leaves it empty.
The `-E' or `--remove-empty-files' option causes
patch to remove output files that are empty after applying a
patch, even if the patch does not appear to be one that removed the
If the patch appears to create a file that already exists,
patch asks for confirmation before applying the patch.