 1. The compressed files are read only. To modify them, first uncompress
    them, modify them, and finally recompress them. If these files are text
    files you may edit them directly using the crypt.el mode of emacs.

 2. Files associated with the boot or shutdown process should not be
    compressed. These files are /etc/fstab, /etc/mtab, /etc/inittab,
    /etc/mount and /etc/umount.

 3. Executables and shared libraries cannot be compressed either. 
    However static libraries (libc.a) and stub libraries (libc.sa) can
    be compressed.
    To compress executables, get the tcx package from your favourite ftp
    site. (tcx compresses only executables, not data files. zlib compresses
    only datafiles, not executables. The two packages should be the ideal 
    partners :-) )

 4. It is useless to compress files which are already smaller than 1k,
    because most filesystems use allocation units of at least 1k.

 5. Static executables won't use the uncompressing libc.
    On certain SUNs, there are still many statically linked binaries. Execute 
    'file program' to see the type of the program (static or dynamic executable)

 6. Zlibc doesn't work with multi-threaded programs (i.e. which use the clone()
    system call.) Fortunately, these programs are extremely rare.

 7. Zlibc doesn't follow symlinks by itself. This work is still done by the
    kernel. Thus when you compress a file, you need to remake all the symlinks
    pointing to it. (See zlibrc.so.3 for details) 
