ldattach(8) — Linux manual page


LDATTACH(8)               System Administration              LDATTACH(8)

NAME         top

       ldattach - attach a line discipline to a serial line

SYNOPSIS         top

       ldattach [-1278denoVh] [-i iflag] [-s speed] ldisc device

DESCRIPTION         top

       The ldattach daemon opens the specified device file (which should
       refer to a serial device) and attaches the line discipline ldisc
       to it for processing of the sent and/or received data. It then
       goes into the background keeping the device open so that the line
       discipline stays loaded.

       The line discipline ldisc may be specified either by name or by

       In order to detach the line discipline, kill(1) the ldattach

       With no arguments, ldattach prints usage information.


       Depending on the kernel release, the following line disciplines
       are supported:

           The default line discipline, providing transparent operation
           (raw mode) as well as the habitual terminal line editing
           capabilities (cooked mode).

           Serial Line IP (SLIP) protocol processor for transmitting
           TCP/IP packets over serial lines.

           Device driver for RS232 connected pointing devices (serial

           Point to Point Protocol (PPP) processor for transmitting
           network packets over serial lines.

       STRIP(4); AX25(5); X25(6)
           Line driver for transmitting X.25 packets over asynchronous
           serial lines.

       6PACK(7); R3964(9)
           Driver for Simatic R3964 module.

           Linux IrDa (infrared data transmission) driver - see

           Synchronous HDLC driver.

           Synchronous PPP driver.

           Bluetooth HCI UART driver.

           Driver for Siemens Gigaset M101 serial DECT adapter.

           Driver for serial line Pulse Per Second (PPS) source.

           Driver for GSM 07.10 multiplexing protocol modem (CMUX).

OPTIONS         top

       -1, --onestopbit
           Set the number of stop bits of the serial line to one.

       -2, --twostopbits
           Set the number of stop bits of the serial line to two.

       -7, --sevenbits
           Set the character size of the serial line to 7 bits.

       -8, --eightbits
           Set the character size of the serial line to 8 bits.

       -d, --debug
           Keep ldattach in the foreground so that it can be interrupted
           or debugged, and to print verbose messages about its progress
           to standard error output.

       -e, --evenparity
           Set the parity of the serial line to even.

       -i, --iflag value...
           Set the specified bits in the c_iflag word of the serial
           line. The given value may be a number or a symbolic name. If
           value is prefixed by a minus sign, the specified bits are
           cleared instead. Several comma-separated values may be given
           in order to set and clear multiple bits.

       -n, --noparity
           Set the parity of the serial line to none.

       -o, --oddparity
           Set the parity of the serial line to odd.

       -s, --speed value
           Set the speed (the baud rate) of the serial line to the
           specified value.

       -c, --intro-command string
           Define an intro command that is sent through the serial line
           before the invocation of ldattach. E.g. in conjunction with
           line discipline GSM0710, the command 'AT+CMUX=0\r' is
           commonly suitable to switch the modem into the CMUX mode.

       -p, --pause value
           Sleep for value seconds before the invocation of ldattach.
           Default is one second.

       -h, --help
           Display help text and exit.

       -V, --version
           Print version and exit.

AUTHORS         top

       Tilman Schmidt <tilman@imap.cc>

SEE ALSO         top

       inputattach(1), ttys(4)

REPORTING BUGS         top

       For bug reports, use the issue tracker at

AVAILABILITY         top

       The ldattach command is part of the util-linux package which can
       be downloaded from Linux Kernel Archive
       <https://www.kernel.org/pub/linux/utils/util-linux/>. This page
       is part of the util-linux (a random collection of Linux
       utilities) project. Information about the project can be found at
       ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩. If you have
       a bug report for this manual page, send it to
       util-linux@vger.kernel.org. This page was obtained from the
       project's upstream Git repository
       ⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on
       2024-06-14. (At that time, the date of the most recent commit
       that was found in the repository was 2024-06-10.) If you discover
       any rendering problems in this HTML version of the page, or you
       believe there is a better or more up-to-date source for the page,
       or you have corrections or improvements to the information in
       this COLOPHON (which is not part of the original manual page),
       send a mail to man-pages@man7.org

util-linux 2.39.594-1e0ad      2023-07-19                    LDATTACH(8)

Pages that refer to this page: ioctl_tty(2)