GDBSERVER(1)		     GNU Development Tools		  GDBSERVER(1)


NAME
       gdbserver - Remote Server for the GNU Debugger

SYNOPSIS
       gdbserver comm prog [args...]

       gdbserver --attach comm pid

       gdbserver --multi comm

DESCRIPTION
       gdbserver is a program that allows you to run GDB on a different
       machine than the one which is running the program being debugged.

       Usage (server (target) side):

       First, you need to have a copy of the program you want to debug put
       onto the target system.	The program can be stripped to save space if
       needed, as gdbserver doesn't care about symbols.	 All symbol handling
       is taken care of by the GDB running on the host system.

       To use the server, you log on to the target system, and run the
       gdbserver program.  You must tell it (a) how to communicate with GDB,
       (b) the name of your program, and (c) its arguments.  The general
       syntax is:

	       target> gdbserver <comm> <program> [<args> ...]

       For example, using a serial port, you might say:

	       target> gdbserver /dev/com1 emacs foo.txt

       This tells gdbserver to debug emacs with an argument of foo.txt, and to
       communicate with GDB via /dev/com1.  gdbserver now waits patiently for
       the host GDB to communicate with it.

       To use a TCP connection, you could say:

	       target> gdbserver host:2345 emacs foo.txt

       This says pretty much the same thing as the last example, except that
       we are going to communicate with the "host" GDB via TCP.	 The
       "host:2345" argument means that we are expecting to see a TCP
       connection from "host" to local TCP port 2345.  (Currently, the "host"
       part is ignored.)  You can choose any number you want for the port
       number as long as it does not conflict with any existing TCP ports on
       the target system.  This same port number must be used in the host GDBs
       "target remote" command, which will be described shortly.  Note that if
       you chose a port number that conflicts with another service, gdbserver
       will print an error message and exit.

       gdbserver can also attach to running programs.  This is accomplished
       via the --attach argument.  The syntax is:

	       target> gdbserver --attach <comm> <pid>

       pid is the process ID of a currently running process.  It isn't
       necessary to point gdbserver at a binary for the running process.

       To start "gdbserver" without supplying an initial command to run or
       process ID to attach, use the --multi command line option.  In such
       case you should connect using "target extended-remote" to start the
       program you want to debug.

	       target> gdbserver --multi <comm>

       Usage (host side):

       You need an unstripped copy of the target program on your host system,
       since GDB needs to examine its symbol tables and such.  Start up GDB as
       you normally would, with the target program as the first argument.
       (You may need to use the --baud option if the serial line is running at
       anything except 9600 baud.)  That is "gdb TARGET-PROG", or "gdb --baud
       BAUD TARGET-PROG".  After that, the only new command you need to know
       about is "target remote" (or "target extended-remote").	Its argument
       is either a device name (usually a serial device, like /dev/ttyb), or a
       "HOST:PORT" descriptor.	For example:

	       (gdb) target remote /dev/ttyb

       communicates with the server via serial line /dev/ttyb, and:

	       (gdb) target remote the-target:2345

       communicates via a TCP connection to port 2345 on host `the-target',
       where you previously started up gdbserver with the same port number.
       Note that for TCP connections, you must start up gdbserver prior to
       using the `target remote' command, otherwise you may get an error that
       looks something like `Connection refused'.

       gdbserver can also debug multiple inferiors at once, described in the
       GDB manual in node "Inferiors Connections and Programs" -- shell
       command "info -f gdb -n 'Inferiors Connections and Programs'".  In such
       case use the "extended-remote" GDB command variant:

	       (gdb) target extended-remote the-target:2345

       The gdbserver option --multi may or may not be used in such case.

OPTIONS
       There are three different modes for invoking gdbserver:

       •   Debug a specific program specified by its program name:

		   gdbserver <comm> <prog> [<args>...]

	   The comm parameter specifies how should the server communicate with
	   GDB; it is either a device name (to use a serial line), a TCP port
	   number (":1234"), or "-" or "stdio" to use stdin/stdout of
	   "gdbserver".	 Specify the name of the program to debug in prog.
	   Any remaining arguments will be passed to the program verbatim.
	   When the program exits, GDB will close the connection, and
	   "gdbserver" will exit.

       •   Debug a specific program by specifying the process ID of a running
	   program:

		   gdbserver --attach <comm> <pid>

	   The comm parameter is as described above.  Supply the process ID of
	   a running program in pid; GDB will do everything else.  Like with
	   the previous mode, when the process pid exits, GDB will close the
	   connection, and "gdbserver" will exit.

       •   Multi-process mode -- debug more than one program/process:

		   gdbserver --multi <comm>

	   In this mode, GDB can instruct gdbserver which command(s) to run.
	   Unlike the other 2 modes, GDB will not close the connection when a
	   process being debugged exits, so you can debug several processes in
	   the same session.

       In each of the modes you may specify these options:

       --help
	   List all options, with brief explanations.

       --version
	   This option causes gdbserver to print its version number and exit.

       --attach
	   gdbserver will attach to a running program.	The syntax is:

		   target> gdbserver --attach <comm> <pid>

	   pid is the process ID of a currently running process.  It isn't
	   necessary to point gdbserver at a binary for the running process.

       --multi
	   To start "gdbserver" without supplying an initial command to run or
	   process ID to attach, use this command line option.	Then you can
	   connect using "target extended-remote" and start the program you
	   want to debug.  The syntax is:

		   target> gdbserver --multi <comm>

       --debug[=option1,option2,...]
	   Instruct "gdbserver" to display extra status information about the
	   debugging process.  This option is intended for "gdbserver"
	   development and for bug reports to the developers.

	   Each option is the name of a component for which debugging should
	   be enabled.	The list of possible options is all, threads, event-
	   loop, remote.  The special option all enables all components.  The
	   option list is processed left to right, and an option can be
	   prefixed with the "-" character to disable output for that
	   component, so you could write:

		   target> gdbserver --debug=all,-event-loop

	   to turn on debug output for all components except event-loop.  If
	   no options are passed to --debug then this is treated as equivalent
	   to --debug=threads.	This could change in future releases of
	   "gdbserver".

       --debug-file=filename
	   Instruct "gdbserver" to send any debug output to the given
	   filename.  This option is intended for "gdbserver" development and
	   for bug reports to the developers.

       --debug-format=option1[,option2,...]
	   Instruct "gdbserver" to include extra information in each line of
	   debugging output.

       --wrapper
	   Specify a wrapper to launch programs for debugging.	The option
	   should be followed by the name of the wrapper, then any command-
	   line arguments to pass to the wrapper, then "--" indicating the end
	   of the wrapper arguments.

       --once
	   By default, gdbserver keeps the listening TCP port open, so that
	   additional connections are possible.	 However, if you start
	   "gdbserver" with the --once option, it will stop listening for any
	   further connection attempts after connecting to the first GDB
	   session.

ENVIRONMENT
SEE ALSO
       The full documentation for GDB is maintained as a Texinfo manual.  If
       the "info" and "gdb" programs and GDB's Texinfo documentation are
       properly installed at your site, the command

	       info gdb

       should give you access to the complete manual.

       Using GDB: A Guide to the GNU Source-Level Debugger, Richard M.
       Stallman and Roland H. Pesch, July 1991.

COPYRIGHT
       Copyright (c) 1988-2024 Free Software Foundation, Inc.

       Permission is granted to copy, distribute and/or modify this document
       under the terms of the GNU Free Documentation License, Version 1.3 or
       any later version published by the Free Software Foundation; with the
       Invariant Sections being "Free Software" and "Free Software Needs Free
       Documentation", with the Front-Cover Texts being "A GNU Manual," and
       with the Back-Cover Texts as in (a) below.

       (a) The FSF's Back-Cover Text is: "You are free to copy and modify this
       GNU Manual.  Buying copies from GNU Press supports the FSF in
       developing GNU and promoting software freedom."

gdb-16.3			  2025-04-20			  GDBSERVER(1)