Multics (from Multiplexed Information and Computing Service) was an influential time-sharing operating system developed during the 1960s in a joint project by MIT's Project MAC, General Electric, and Bell Labs. Multics was commercialized by Honeywell and Groupe Bull for their mainframe hardware, reaching a peak of about 80 installations worldwide by the early 1980s. The last known Multics site running on real hardware was operated by the Canadian Department of National Defence and was shut down on October 30, 2000.
Although commercially disappointing, Multics enjoyed a reputation as a highly secure operating system. Multics developers pioneered a number of operating system concepts such as the hierarchical file system and system programming in a high-level language that were later popularized in the Unix operating system and have become standard in current operating systems.
The Living Computer's simulated Honeywell 6180 system runs Multics version MR12.6e.
The Multics user environment will be very familiar to Unix-style shell users. In fact, many Unix shell command names were inspired by Multics commands.
Multics resolves meaningful command versus easy typing tradeoff by having it both ways: Every command has a long meaningful name with the most frequently used commands also given a short 2-3 character alias. (Unix developers tended to adopt the short command aliases and forget the meaningful names.) Multics commands are case-sensitive.
Multics documentation uses the term segment to refer to files.
Linux-to-Multics Command Mapping has a list of corresponding commands in Unix and Multics.
There are a differences between Unix and Multics that should be kept in mind:
>) is used as a directory separator instead of Unix's slash (
/). The less-than character (
<) is used to refer to the current working directory's parent directory instead of Unix's (
cdin Unix changes the current working directory, but in Multics creates a new directory (long form
create_dir). (To change the current directory in Multics, use the command
Get help on Multics with the
help command, instead of
man on Unix.