dtach - simple program that emulates the detach feature of screen.
dtach -a <socket> <options>
dtach -A <socket> <options> <command...>
dtach -c <socket> <options> <command...>
dtach -n <socket> <options> <command...>
dtach is a program that emulates the detach feature of screen. It is
designed to be transparent and un-intrusive; it avoids interpreting the
input and output between attached terminals and the program under its
control. Consequently, it works best with full-screen applications such
dtach is intended for users who want the detach feature of screen with-
out the other overhead of screen. It is tiny, does not use many
libraries, and stays out of the way as much as possible.
A session in dtach is a single instance in which a program is running
under the control of dtach. The program is disassociated from the
original terminal, and is thus protected from your original terminal
being disconnected for some reason.
Other instances of dtach can attach themselves to a particular session.
Input and output is copied between the program running in the dtach
session, and the attached terminals.
dtach avoids interpreting the communication stream between the program
and the attached terminals; it instead relies on the ability of the
attached terminals to manage the screen.
Sessions are represented by Unix-domain sockets in the filesystem. No
other permission checking other than the filesystem access checks is
performed. dtach creates a master process that monitors the session
socket, the program, and any attached terminals.
dtach has several modes of operation. It can create a new session in
which a program is executed, or it can attach to an existing session.
The first argument specifies which mode dtach should operate in.
-a Attach to an existing session. dtach attaches itself to the
session specified by <socket>. After the attach is completed,
the window size of the current terminal is sent to the master
process, and a redraw is also requested.
-A Attach to an existing session, or create a new one. dtach first
tries to attach to the session specified by <socket> if possi-
ble. If the attempt to open the socket fails, dtach tries to
create a new session before attaching to it.
-c Creates a new session. A new session is created in which the
specified program is executed. dtach then tries to attach
itself to the newly created session.
-n Creates a new session, without attaching to it. A new session is
created in which the specified program is executed. dtach does
not try to attach to the newly created session, however, and
dtach has a few options that allow you to modify its behavior. Each
attaching process can have separate settings for these options, which
allows for some flexibility.
Sets the detach character to <char>. When the detach character
is pressed, dtach detaches itself from the current session and
exits. The process running in the session is unaffected by the
detach. By default, the detach character is set to ^\ (Ctrl-\).
-E Disables the detach character. dtach does not try to scan input
from the terminal for a detach character. The only way to detach
from the session is then by sending the attaching process an
Sets the redraw method to <method>. The valid methods are none,
ctrl_l, or winch.
none disables redrawing completely, ctrl_l sends a Ctrl L char-
acter to the program if the terminal is in character-at-a-time
and no-echo mode, and winch forces a WINCH signal to be sent to
When creating a new session, the specified method is used as the
default redraw method for the session. If not specified, the
ctrl_l method is used.
-z Disables processing of the suspend key. Normally, dtach will
suspend itself when the suspend key is pressed. With this
option, the suspend character is sent to the session instead of
being handled by dtach.
The following example creates a new session that has the detach charac-
ter and suspend processing disabled. A socket is created in the /tmp
directory for the session.
$ dtach -c /tmp/foozle -Ez bash
The following example attaches to the /tmp/foozle session if it exists,
and if not, creates a new session using /tmp/foozle as the socket for
the session. Processing of the suspend character is also disabled for
the attach instance.
$ dtach -A /tmp/foozle -z bash
The following example attaches to the /tmp/foozle session, using the
winch redraw method to redraw the screen.
$ dtach -a /tmp/foozle -r winch
The following example creates a new session and sets the default redraw
method for the session to the winch redraw method.
$ dtach -c /tmp/foozle -r winch bash
Ned T. Crigler <email@example.com>.
dtach 0.7 Jul 2004 dtach(1)
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