THE META KEY

THE META KEY

If you venture into the Readline documentation, which can be found in the“READLINE” section of the bash man page, you will encounter the term metakey. On modern keyboards this maps to the ALT key, but it wasn’t always so.
Back in the dim times (before PCs but after Unix) not everybody had theirown computer. What they might have had was a device called a terminal. A terminal was a communication device that featured a text-display screen and akeyboard and had just enough electronics inside to display text characters andmove the cursor around. It was attached (usually by serial cable) to a larger computer or the communication network of a larger computer. There weremany different brands of terminals, and they all had different keyboards anddisplay feature sets. Since they all tended to at least understand ASCII, softwaredevelopers wanting portable applications wrote to the lowest common denominator. Unix systems have a very elaborate way of dealing with terminals andtheir different display features. Since the developers of Readline could not besure of the presence of a dedicated extra control key, they invented one andcalled it meta. While the ALT key serves as the meta key on modern keyboards,you can also press and release the ESC key to get the same effect as holdingdown the ALT key if you’re still using a terminal (which you can still do inLinux!).