A Universally Unique Identifier (UUID) is an identifier standard used in software construction whose intent is to enable distributed systems to uniquely identify information without significant central coordination.

Typically, a UUID consists of 32 hexadecimal digits, displayed in 5 groups separated by hyphens, e.g.:


Getting UUIDs

To get a list of the UUIDs for your partitions:


Most source files (and sometimes programs and files) that you download from the Internet come packaged as "tarballs". A tarball is an archive file similar to "zip" files in Windows world. The name comes from its original purpose, storing data in Magnetic Tapes (Tape ARchiver), and usually has the .tar extension. When it is compressed, it is .tar.gz (sometimes shortened to .tgz) or .tar.bz2. Extracting the files from the tarball is called "untaring".


PATH is an environment variable that is a list of directories that the operating system looks in to find commands issued by the user. For example, when you type ls to list files, you are actually executing /bin/ls because the /bin directory is in your path by default. There may be times when you will want to add a new location to PATH, whether temporarily or permanently.


From Wikipedia: The BIOS (Basic Input/Output System) is boot firmware, designed to be the first code run by a PC when powered on. The initial function of the BIOS is to identify, test, and initialize system devices such as the video display card, hard disk, and floppy disk and other hardware. This is to prepare the machine into a known state, so that software stored on compatible media can be loaded, executed, and given control of the PC.


You can provide your own name for commands using the alias command. An alias allows a user to create simple names or abbreviations (even consisting of just a single character) for commands, regardless of how complex the original commands are, and then use them in the same way that ordinary commands are used.


In its simplest form, you just set the  command name you want to use equal to the original command, which you surround with single quotes. For example, if a user wants to exit with a personal command such as cu (i.e., "see you"):



A computer firewall is simply a piece of hardware or software that prevents unwanted, possibly malicious, outside access to your computer through your Internet connection. In its simplest and strictest sense, such firewalls block or simply ignore incoming attempts by outside systems to establish a connection to your computer, while, at the same time, allowing your computer to originate and establish connections with other outside systems.


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