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 process.

       With no arguments, ldattach prints usage information.


       Depending on the kernel release, the following line disciplines are

       TTY(0) 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

       PPP(3) Point to Point Protocol (PPP) processor for transmitting
              network packets over serial lines.



       X25(6) Line driver for transmitting X.25 packets over asynchronous
              serial lines.


              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.

       -V, --version
              Display version information and exit.

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

SEE ALSO         top

       inputattach(1), ttys(4)

AUTHOR         top

       Tilman Schmidt (

AVAILABILITY         top

       The ldattach command is part of the util-linux package and is
       available from

COLOPHON         top

       This page is part of the util-linux (a random collection of Linux
       utilities) project.  Information about the project can be found at 
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util-linux                        July 2014                      LDATTACH(8)