dtach is a program written in C that emulates the detach feature of
screen, which allows a program to be executed in an environment that is
protected from the controlling terminal. For instance, the program under
the control of dtach would not be affected by the terminal being
disconnected for some reason.

dtach was written because screen did not adequately meet my needs; I did
not need the other features of screen, such as its support of multiple
terminals or its terminal emulation support. screen was also too big,
bulky, and the source code was also difficult to understand.

screen also interfered with my use of full-screen applications such as
emacs and ircII, since screen excessively interprets the stream between
the program and the attached terminals. dtach does not have a terminal
emulation layer, and passes the raw output stream of the program to the
attached terminals. The input processing that dtach performs is
scanning for the detach character (which signals dtach to detach from
the program) and processing the suspend key (which tells dtach to
temporarily suspend itself without affecting the running program), which
can both be disabled if desired.

Contrary to screen, dtach has minimal features, and is extremely tiny.
The small size allows it to be more easily audited for bugs and security
holes, and also allows it to fit in environments where space is limited,
such as on rescue disks.

dtach has only been tested on the Linux/x86 platform, however it should
be easily portable to other variants of Unix. It currently assumes that
the host system uses POSIX termios, and has a working forkpty function
available.