[Bug-tar] Unable to uncompress .Z files without a "compress" binary

[Hrvoje Nikšić]

I reported this bug in launchpad some years ago, but I see no
indication that the launchpad people forwarded it upstream, so I'm
doing it now myself. The bug was first noticed with an older version
of tar, but as far as I can tell, it persists with 1.23.


Tar appears unable to uncompress a .Z file (produced with the
"compress" utility) without the "compress" binary being present on the
system. This should not be necessary because "gzip" is (and always has
been) quite capable of uncompressing compress-ed binaries.

To repeat:

1. obtain a .tar.Z file, e.g.
ftp://aixpdslib.seas.ucla.edu/pub/ldd/RISC/5.1/exec/ldd.1.0.tar.Z

2. Execute:
    tar xf ldd.1.0.tar.Z

Expected result: the tar file is uncompressed.

Actual result: error:

tar: compress: Cannot exec: No such file or directory
tar: Error is not recoverable: exiting now
tar: Child returned status 2
tar: Error exit delayed from previous errors

As a workaround, one can add the "z" flag to force the use of gunzip
for decompression. However, the "z" flag should not be necessary and
is confusing, since tar is obviously quite capable of recognizing the
format.