When you create a *.jar file using jar command-line tool, it is worth to remember that the order of arguments does matter, so:
jar cmvf projects/myTags/etc/MANIFEST.MF myTags.war myTags
means that you must firstly provide the manifest file (m), than the JAR filename (f).
If you use the same order of arguments but change the switches like this:
jar cvfm projects/myTags/etc/MANIFEST.MF myTags.war myTags
the command will not be executed. According to the switches, your first argument should be the JAR filename (f) and then manifest file (m).