File (de)compression

tar -zxvf filename.tar.gz
(=tape archiver) Untar a tarred and compressed tarball (*.tar.gz or *.tgz) that you downloaded from the Internet.

tar -xvf filename.tar
Untar a tarred but uncompressed tarball (*.tar).

gunzip filename.gz
Decompress a zipped file (*.gz" or *.z). Use gzip (also zip or compress) if you wanted to compress files to this file format.

bunzip2 filename.bz2
(=big unzip) Decompress a file (*.bz2) zipped with bzip2 compression utility. Used for big files.

unzip filename.zip
Decompress a file (*.zip) zipped with a compression utility compatible with PKZIP for DOS.

unarj e filename.arj
Extract the content of an *.arj archive.

uudecode -o outputfile filename
Decode a file encoded with uuencode. uu-encoded files are typically used for transfer of non-text files in e-mail (uuencode transforms any file into an ASCII file).