The chmod command is a tool in Unix and Unix-like operating systems for changing the access permissions of files and directories. It appeared in the earliest versions of Unix, created by Ken Thompson, Dennis Ritchie and their colleagues at Bell Laboratories, and it is documented in the first edition of the Unix Programmer's Manual, which is dated from the end of 1971. The permissions determine who may read, write or execute a file, and they are set separately for the owner, for the owner's group and for everyone else. They can be given as a three-digit octal number or in a symbolic form such as u+x. The command and the permission model remain in use on Linux and macOS.
Before and after
- 15 September 1971Greenpeace sails on its first voyage
- 18 September 1971Birth of Anna Netrebko
- 20 October 1971Birth of Snoop Dogg
- from 27 October 1971 to 16 May 1997Zaire
- 3 November 1971Invention of chmod
- 12 November 1971Establishment of Arches National Park
- 14 November 1971Mariner 9 becomes the first spacecraft to orbit another planet
- 15 November 1971Intel 4004
- from 3 December 1971 to 16 December 1971Indo-Pakistani War of 1971
More in Science & technology
- 1949Discovery of berkelium
- 1955Discovery of mendelevium
- 14 February 1961Discovery of lawrencium
- 8 December 1994Discovery of roentgenium
- 1996Discovery of copernicium
- 2006Discovery of nihonium
The era
This moment belongs to the Contemporary world (1945 CE to today), the world since 1945. You can also browse everything in the 20th century.