Question

I created a wordcount example in MapReduce and trying to make the jar file using following command:

hduseros@MT2012018:/usr/local/hadoop$ jar -cvf playground/wordcount.jar -C playground/classes

But Its not at all running and giving me following result:

hduseros@MT2012018:/usr/local/hadoop$ jar -cvf playground/wordcount.jar -C playground/classes
Usage: jar {ctxui}[vfm0Me] [jar-file] [manifest-file] [entry-point] [-C dir] files ...
Options:
    -c  create new archive
    -t  list table of contents for archive
    -x  extract named (or all) files from archive
    -u  update existing archive
    -v  generate verbose output on standard output
    -f  specify archive file name
    -m  include manifest information from specified manifest file
    -e  specify application entry point for stand-alone application 
        bundled into an executable jar file
    -0  store only; use no ZIP compression
    -M  do not create a manifest file for the entries
    -i  generate index information for the specified jar files
    -C  change to the specified directory and include the following file
If any file is a directory then it is processed recursively.
The manifest file name, the archive file name and the entry point name are
specified in the same order as the 'm', 'f' and 'e' flags.

Example 1: to archive two class files into an archive called classes.jar: 
       jar cvf classes.jar Foo.class Bar.class 
Example 2: use an existing manifest file 'mymanifest' and archive all the
           files in the foo/ directory into 'classes.jar': 
       jar cvfm classes.jar mymanifest -C foo/ .

Please correct where I am wrong. I have set the class path. I can run the examples already present but not able to make jar file.

Answer 1

That is probably because you haven’t given it the location where it needs to pick the files from. Try this:

jar -cvf playground/wordcount.jar -C playground/classes .

And include the last dot (.)