ed
Unix-like operating system command
ed is a line editor for Unix and Unix-like operating systems. It was one of the first parts of the Unix operating system that was developed, in August 1969. It remains part of the POSIX and Open Group standards for Unix-based operating systems,... Wikipedia
Initial release: 1973, 50–51 years ago
Operating system: Unix, Unix-like, Plan 9
Original author(s): Ken Thompson
Written in: C