File Compression command
tar -zcvf filename.tar.gz filename
tar -jcvf filename.tar.bz2 filename
File decompression command
tar -zxcf filename.tar.gz
tar -jxvf filename.tar.bz2
Extract the files to a specific directory
tar -zxcf filename.tar.gz -C dirname
tar -jxvf filename.tar.bz2 -C dirname