Useful Commands

If you constantly forget a command and need to reference it, here is a good place to deposit that information.

Command Lines

• tar a directory: tar cfz filename.tar.gz directoryname
• Check what is in a tar file: tar tfz filename.tar.gz
• Uncompress and untar a file: tar -xzf filename.tar.gz
• Zip a file: zip -r foo foo or zip stuff *
• Disk Usage: du -ms .
• Extract Java Files: jar -xvf filename.jar
• Make cd and iso images:
  • mkisofs -o something.iso directory_name
  • cdrecord dev=15,0,0 driveropts=burnfree something.iso
• Mount external hard drive: mount -t ntfs /dev/sd0e /mnt/scratch/harddisk/

Bits and Bytes

• 1 bit = a 1 or 0 (b)
• 4 bits = 1 nybble (?)
• 8 bits = 1 byte (B)
• 1024 bytes = 1 Kilobyte (KB)
• 1024 Kilobytes = 1 Megabyte (MB)
• 1024 Megabytes = 1 Gigabyte (GB)
• 1024 Gigabytes = 1 Terabyte (TB)