How to update one file in a zip archive

I've found the Linux zip file to be cumbersome for replacing a single file in a zip. The jar utility from the Java Development Kit may be easier. Consider the common task of updating WEB/web.xml in a JAR file (which is just a zip file):

jar -uf path/to/myapp.jar -C path/to/dir WEB-INF/web.xml

Here, path/to/dir is the path to a directory containing the WEB-INF directory (which in turn contains web.xml).

From zip(1):

When given the name of an existing zip archive, zip will replace identically named entries in the zip archive or add entries for new names.

So just use the zip command as you normally would to create a new .zip file containing only that one file, except the .zip filename you specify will be the existing archive.

Try the following:

zip [zipfile] [file to update] 

An example:

$ zip test.zip test/test.txt
updating: test/test.txt (stored 0%)