Provided by: util-linux_2.38.1-4ubuntu1_amd64 bug


       agetty - alternative Linux getty


       agetty [options] port [baud_rate...] [term]


       agetty opens a tty port, prompts for a login name and invokes the /bin/login command. It
       is normally invoked by init(8).

       agetty has several non-standard features that are useful for hardwired and for dial-in

       •   Adapts the tty settings to parity bits and to erase, kill, end-of-line and uppercase
           characters when it reads a login name. The program can handle 7-bit characters with
           even, odd, none or space parity, and 8-bit characters with no parity. The following
           special characters are recognized: Control-U (kill); DEL and backspace (erase);
           carriage return and line feed (end of line). See also the --erase-chars and
           --kill-chars options.

       •   Optionally deduces the baud rate from the CONNECT messages produced by
           Hayes(tm)-compatible modems.

       •   Optionally does not hang up when it is given an already opened line (useful for
           call-back applications).

       •   Optionally does not display the contents of the /etc/issue file.

       •   Optionally displays an alternative issue files or directories instead of /etc/issue or

       •   Optionally does not ask for a login name.

       •   Optionally invokes a non-standard login program instead of /bin/login.

       •   Optionally turns on hardware flow control.

       •   Optionally forces the line to be local with no need for carrier detect.

       This program does not use the /etc/gettydefs (System V) or /etc/gettytab (SunOS 4) files.


           A path name relative to the /dev directory. If a "-" is specified, agetty assumes that
           its standard input is already connected to a tty port and that a connection to a
           remote user has already been established.

           Under System V, a "-" port argument should be preceded by a "--".

           A comma-separated list of one or more baud rates. Each time agetty receives a BREAK
           character it advances through the list, which is treated as if it were circular.

           Baud rates should be specified in descending order, so that the null character
           (Ctrl-@) can also be used for baud-rate switching.

           This argument is optional and unnecessary for virtual terminals.

           The default for serial terminals is keep the current baud rate (see --keep-baud) and
           if unsuccessful then default to '9600'.

           The value to be used for the TERM environment variable. This overrides whatever
           init(1) may have set, and is inherited by login and the shell.

           The default is 'vt100', or 'linux' for Linux on a virtual terminal, or 'hurd' for GNU
           Hurd on a virtual terminal.


       -8, --8bits
           Assume that the tty is 8-bit clean, hence disable parity detection.

       -a, --autologin username
           Automatically log in the specified user without asking for a username or password.
           Using this option causes an -f username option and argument to be added to the
           /bin/login command line. See --login-options, which can be used to modify this
           option’s behavior.

           Note that --autologin may affect the way in which getty initializes the serial line,
           because on auto-login agetty does not read from the line and it has no opportunity
           optimize the line setting.

       -c, --noreset
           Do not reset terminal cflags (control modes). See termios(3) for more details.

       -E, --remote
           Typically the login(1) command is given a remote hostname when called by something
           such as telnetd(8). This option allows agetty to pass what it is using for a hostname
           to login(1) for use in utmp(5). See --host, login(1), and utmp(5).

           If the --host fakehost option is given, then an -h fakehost option and argument are
           added to the /bin/login command line.

           If the --nohostname option is given, then an -H option is added to the /bin/login
           command line.

           See --login-options.

       -f, --issue-file path
           Specifies a ":" delimited list of files and directories to be displayed instead of
           /etc/issue (or other). All specified files and directories are displayed, missing or
           empty files are silently ignored. If the specified path is a directory then display
           all files with .issue file extension in version-sort order from the directory. This
           allows custom messages to be displayed on different terminals. The --noissue option
           will override this option.

           Display the current issue file (or other) on the current terminal and exit. Use this
           option to review the current setting, it is not designed for any other purpose. Note
           that output may use some default or incomplete information as proper output depends on
           terminal and agetty command line.

       -h, --flow-control
           Enable hardware (RTS/CTS) flow control. It is left up to the application to disable
           software (XON/XOFF) flow protocol where appropriate.

       -H, --host fakehost
           Write the specified fakehost into the utmp file. Normally, no login host is given,
           since agetty is used for local hardwired connections and consoles. However, this
           option can be useful for identifying terminal concentrators and the like.

       -i, --noissue
           Do not display the contents of /etc/issue (or other) before writing the login prompt.
           Terminals or communications hardware may become confused when receiving lots of text
           at the wrong baud rate; dial-up scripts may fail if the login prompt is preceded by
           too much text.

       -I, --init-string initstring
           Set an initial string to be sent to the tty or modem before sending anything else.
           This may be used to initialize a modem. Non-printable characters may be sent by
           writing their octal code preceded by a backslash (\). For example, to send a linefeed
           character (ASCII 10, octal 012), write \12.

       -J, --noclear
           Do not clear the screen before prompting for the login name. By default the screen is

       -l, --login-program login_program
           Invoke the specified login_program instead of /bin/login. This allows the use of a
           non-standard login program. Such a program could, for example, ask for a dial-up
           password or use a different password file. See --login-options.

       -L, --local-line[=mode]
           Control the CLOCAL line flag. The optional mode argument is auto, always or never. If
           the mode argument is omitted, then the default is always. If the --local-line option
           is not given at all, then the default is auto.

               Forces the line to be a local line with no need for carrier detect. This can be
               useful when you have a locally attached terminal where the serial line does not
               set the carrier-detect signal.

               Explicitly clears the CLOCAL flag from the line setting and the carrier-detect
               signal is expected on the line.

               The agetty default. Does not modify the CLOCAL setting and follows the setting
               enabled by the kernel.

       -m, --extract-baud
           Try to extract the baud rate from the CONNECT status message produced by
           Hayes(tm)-compatible modems. These status messages are of the form:
           "<junk><speed><junk>". agetty assumes that the modem emits its status message at the
           same speed as specified with (the first) baud_rate value on the command line.

           Since the --extract-baud feature may fail on heavily-loaded systems, you still should
           enable BREAK processing by enumerating all expected baud rates on the command line.

           Display supported baud rates. These are determined at compilation time.

       -n, --skip-login
           Do not prompt the user for a login name. This can be used in connection with the
           --login-program option to invoke a non-standard login process such as a BBS system.
           Note that with the --skip-login option, agetty gets no input from the user who logs in
           and therefore will not be able to figure out parity, character size, and newline
           processing of the connection. It defaults to space parity, 7 bit characters, and ASCII
           CR (13) end-of-line character. Beware that the program that agetty starts (usually
           /bin/login) is run as root.

       -N, --nonewline
           Do not print a newline before writing out /etc/issue.

       -o, --login-options login_options
           Options and arguments that are passed to login(1). Where \u is replaced by the login
           name. For example:

           --login-options '-h darkstar -- \u'

           See --autologin, --login-program and --remote.

           Please read the SECURITY NOTICE below before using this option.

       -p, --login-pause
           Wait for any key before dropping to the login prompt. Can be combined with --autologin
           to save memory by lazily spawning shells.

       -r, --chroot directory
           Change root to the specified directory.

       -R, --hangup
           Call vhangup(2) to do a virtual hangup of the specified terminal.

       -s, --keep-baud
           Try to keep the existing baud rate. The baud rates from the command line are used when
           agetty receives a BREAK character. If another baud rates specified then the original
           baud rate is also saved to the end of the wanted baud rates list. This can be used to
           return to the original baud rate after unexpected BREAKs.

       -t, --timeout timeout
           Terminate if no user name could be read within timeout seconds. Use of this option
           with hardwired terminal lines is not recommended.

       -U, --detect-case
           Turn on support for detecting an uppercase-only terminal. This setting will detect a
           login name containing only capitals as indicating an uppercase-only terminal and turn
           on some upper-to-lower case conversions. Note that this has no support for any Unicode

       -w, --wait-cr
           Wait for the user or the modem to send a carriage-return or a linefeed character
           before sending the /etc/issue file (or others) and the login prompt. This is useful
           with the --init-string option.

           Do not print hints about Num, Caps and Scroll Locks.

           By default the hostname will be printed. With this option enabled, no hostname at all
           will be shown.

           By default the hostname is only printed until the first dot. With this option enabled,
           the fully qualified hostname by gethostname(3P) or (if not found) by getaddrinfo(3) is

       --erase-chars string
           This option specifies additional characters that should be interpreted as a backspace
           ("ignore the previous character") when the user types the login name. The default
           additional 'erase' has been '#', but since util-linux 2.23 no additional erase
           characters are enabled by default.

       --kill-chars string
           This option specifies additional characters that should be interpreted as a kill
           ("ignore all previous characters") when the user types the login name. The default
           additional 'kill' has been '@', but since util-linux 2.23 no additional kill
           characters are enabled by default.

       --chdir directory
           Change directory before the login.

       --delay number
           Sleep seconds before open tty.

       --nice number
           Run login with this priority.

           Ask all running agetty instances to reload and update their displayed prompts, if the
           user has not yet commenced logging in. After doing so the command will exit. This
           feature might be unsupported on systems without Linux inotify(7).

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

       -V, --version
           Print version and exit.


       This section shows examples for the process field of an entry in the /etc/inittab file.
       You’ll have to prepend appropriate values for the other fields. See inittab(5) for more

       For a hardwired line or a console tty:

          /sbin/agetty 9600 ttyS1

       For a directly connected terminal without proper carrier-detect wiring (try this if your
       terminal just sleeps instead of giving you a password: prompt):

          /sbin/agetty --local-line 9600 ttyS1 vt100

       For an old-style dial-in line with a 9600/2400/1200 baud modem:

          /sbin/agetty --extract-baud --timeout 60 ttyS1 9600,2400,1200

       For a Hayes modem with a fixed 115200 bps interface to the machine (the example init
       string turns off modem echo and result codes, makes modem/computer DCD track modem/modem
       DCD, makes a DTR drop cause a disconnection, and turns on auto-answer after 1 ring):

          /sbin/agetty --wait-cr --init-string 'ATE0Q1&D2&C1S0=1\015' 115200 ttyS1


       If you use the --login-program and --login-options options, be aware that a malicious user
       may try to enter lognames with embedded options, which then get passed to the used login
       program. agetty does check for a leading "-" and makes sure the logname gets passed as one
       parameter (so embedded spaces will not create yet another parameter), but depending on how
       the login binary parses the command line that might not be sufficient. Check that the used
       login program cannot be abused this way.

       Some programs use "--" to indicate that the rest of the command line should not be
       interpreted as options. Use this feature if available by passing "--" before the username
       gets passed by \u.


       The default issue file is /etc/issue. If the file exists, then agetty also checks for
       /etc/issue.d directory. The directory is optional extension to the default issue file and
       content of the directory is printed after /etc/issue content. If the /etc/issue does not
       exist, then the directory is ignored. All files with .issue extension from the directory
       are printed in version-sort order. The directory can be used to maintain 3rd-party
       messages independently on the primary system /etc/issue file.

       Since version 2.35 additional locations for issue file and directory are supported. If the
       default /etc/issue does not exist, then agetty checks for /run/issue and /run/issue.d,
       thereafter for /usr/lib/issue and /usr/lib/issue.d. The directory /etc is expected for
       host specific configuration, /run is expected for generated stuff and /usr/lib for static
       distribution maintained configuration.

       The default path maybe overridden by --issue-file option. In this case specified path has
       to be file or directory and all the default issue file and directory locations are

       The issue file feature can be completely disabled by --noissue option.

       It is possible to review the current issue file by agetty --show-issue on the current

       The issue files may contain certain escape codes to display the system name, date, time et
       cetera. All escape codes consist of a backslash (\) immediately followed by one of the
       characters listed below.

       4 or 4{interface}
           Insert the IPv4 address of the specified network interface (for example: \4{eth0}). If
           the interface argument is not specified, then select the first fully configured (UP,
           non-LOCALBACK, RUNNING) interface. If no configured interface is found, fall back to
           the IP address of the machine’s hostname.

       6 or 6{interface}
           The same as \4 but for IPv6.

           Insert the baudrate of the current line.

           Insert the current date.

       e or e{name}
           Translate the human-readable name to an escape sequence and insert it (for example:
           \e{red}Alert text.\e{reset}). If the name argument is not specified, then insert \033.
           The currently supported names are: black, blink, blue, bold, brown, cyan, darkgray,
           gray, green, halfbright, lightblue, lightcyan, lightgray, lightgreen, lightmagenta,
           lightred, magenta, red, reset, reverse, yellow and white. All unknown names are
           silently ignored.

           Insert the system name (the name of the operating system). Same as 'uname -s'. See
           also the \S escape code.

       S or S{VARIABLE}
           Insert the VARIABLE data from /etc/os-release. If this file does not exist then fall
           back to /usr/lib/os-release. If the VARIABLE argument is not specified, then use
           PRETTY_NAME from the file or the system name (see \s). This escape code can be used to
           keep /etc/issue distribution and release independent. Note that \S{ANSI_COLOR} is
           converted to the real terminal escape sequence.

           Insert the name of the current tty line.

           Insert the architecture identifier of the machine. Same as uname -m.

           Insert the nodename of the machine, also known as the hostname. Same as uname -n.

           Insert the NIS domainname of the machine. Same as hostname -d.

           Insert the DNS domainname of the machine.

           Insert the release number of the OS. Same as uname -r.

           Insert the current time.

           Insert the number of current users logged in.

           Insert the string "1 user" or "<n> users" where <n> is the number of current users
           logged in.

           Insert the version of the OS, that is, the build-date and such.

       An example. On my system, the following /etc/issue file:

           This is \n.\o (\s \m \r) \t

       displays as:

           This is (Linux i386 1.1.9) 18:29:30


           the system status file.

           printed before the login prompt.

       /etc/os-release /usr/lib/os-release
           operating system identification data.

           problem reports (if syslog(3) is not used).

           init(8) configuration file for SysV-style init daemon.


       The baud-rate detection feature (the --extract-baud option) requires that agetty be
       scheduled soon enough after completion of a dial-in call (within 30 ms with modems that
       talk at 2400 baud). For robustness, always use the --extract-baud option in combination
       with a multiple baud rate command-line argument, so that BREAK processing is enabled.

       The text in the /etc/issue file (or other) and the login prompt are always output with
       7-bit characters and space parity.

       The baud-rate detection feature (the --extract-baud option) requires that the modem emits
       its status message after raising the DCD line.


       Depending on how the program was configured, all diagnostics are written to the console
       device or reported via the syslog(3) facility. Error messages are produced if the port
       argument does not specify a terminal device; if there is no utmp entry for the current
       process (System V only); and so on.


       Werner Fink <>, Karel Zak <>

       The original agetty for serial terminals was written by W.Z. Venema
       <> and ported to Linux by Peter Orbaek <>.


       For bug reports, use the issue tracker at


       The agetty command is part of the util-linux package which can be downloaded from Linux
       Kernel Archive <>.