Streaming from zip to bz2

I’ve got a massive bunch of zip archives, each of which contains only a single file. And the name of the enclosed file varies. Dealing with these data is painful.

It’d be a lot more convenient if the files were compressed with gzip or bzip2 and had a consistent naming convention. How would you go about making that conversion without actually unpacking the zip archive, finding the name of the enclosed file and then recompressing? Enter funzip.

To illustrate, first we create a zip archive with a single file.

$ ls -l foo.txt
-rw-rw-r- 1 user user 2311 Jul 8 14:06 foo.txt
$ zip foo.txt
  adding: foo.txt (deflated 62%)
$ ls -l
-rw-rw-r- 1 user user 1031 Jul 8 14:06

Then extract the single file to standard output using funzip and pipe the results through bzip2.

$ funzip | bzip2 >foo.bz2
$ ls -l foo.bz2
-rw-rw-r- 1 user user 924 Jul 8 14:06 foo.bz2

Another, more robust, approach is to simply use unzip with -c (extract to stdout) and -qq (be super quiet).

unzip -qq -c | bzip2 >foo.bz2