getty

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A getty is the generic name for a program which manages a terminal line and its connected terminal. Its purpose is to protect the system from unauthorized access. Generally, each getty process is started by systemd and manages a single terminal line.

Installation

agetty is the default getty in Arch Linux, as part of the util-linux package.

An alternative is:

  • mingetty — A minimal getty which allows automatic logins.
mingettyAUR || mingettyAUR

Tips and tricks

Staircase effect

agetty modifies the TTY settings while waiting for a login so that the newlines are not translated to CR-LFs. This tends to cause a "staircase effect" for messages printed to the console.

It is entirely harmless, but in the event it persists once logged, you can fix this behavior with: 

$ stty onlcr

See this forums discussion on the subject.

Add additional virtual consoles

Agetty manages virtual consoles and six of these virtual consoles are provided by default in Arch Linux. They are usually accessible by pressing Ctrl+Alt+F1 through Ctrl+Alt+F6.

Open the file /etc/systemd/logind.conf and set the option NAutoVTs=6 to the number of virtual terminals that you want at boot.

If needed, it is possible to temporarily start a getty@ttyN.service service directly.

Automatic login to virtual console

Configuration relies on systemd unit drop-in files to override the default parameters passed to agetty.

Configuration differs for virtual versus serial consoles. In most cases, you want to set up automatic login on a virtual console, (whose device name is ttyN, where N is a number). The configuration of automatic login for serial consoles will be slightly different. Device names of the serial consoles look like ttySN, where N is a number.

Tip: Consider using greetd's auto-login feature. It will not auto-login a second time if the initial session exits, but will show a login screen instead.

Virtual console

Create a drop-in file for getty@tty1.service with the following contents: 

/etc/systemd/system/getty@tty1.service.d/autologin.conf
[Service]
ExecStart=
ExecStart=-/sbin/agetty -o '-p -f -- \\u' --noclear --autologin username %I $TERM
Tip:
  • The option Type=idle found in the default getty@.service will delay the service startup until all jobs (state change requests to units) are completed in order to avoid polluting the login prompt with boot-up messages. When starting X automatically, it may be useful to start getty@tty1.service immediately by adding Type=simple into the drop-in file. Both the init system and startx can be silenced to avoid the interleaving of their messages during boot-up.
  • See Silent boot#agetty for an example virtual console drop-in file which hides the login prompt completely.
  • The above snippet will cause the loginctl session type to be set to tty. If desirable (for example if starting X automatically), it is possible to manually set the session type to wayland or x11 by adding Environment=XDG_SESSION_TYPE=x11 or Environment=XDG_SESSION_TYPE=wayland into this file.

If you do not want full automatic login, but also do not want to type your username, see #Prompt only the password for a default user in virtual console login.

If you want to use a tty other than tty1, see systemd/FAQ#How do I change the default number of gettys?.

Serial console

Create a drop-in file: 

/etc/systemd/system/serial-getty@ttyS0.service.d/autologin.conf
[Service]
ExecStart=
ExecStart=-/sbin/agetty -o '-p -f -- \\u' --keep-baud --autologin username 115200,57600,38400,9600 - $TERM

Nspawn console

To configure auto-login for a systemd-nspawn container, override console-getty.service by creating a drop-in file: 

/etc/systemd/system/console-getty.service.d/autologin.conf
[Service]
ExecStart=
ExecStart=-/sbin/agetty -o '-p -f -- \\u' --noclear --keep-baud --autologin username - 115200,38400,9600 $TERM

If machinectl login my-container method is used to access the container, also adjust the container-getty@.service template that manages pts/[0-9] pseudo ttys: 

/etc/systemd/system/container-getty@.service.d/autologin.conf
[Service]
ExecStart=
ExecStart=-/sbin/agetty -o '-p -f -- \\u' --noclear --keep-baud --autologin username - 115200,38400,9600 $TERM

Prompt only the password for a default user in virtual console login

Getty can be used to login from a virtual console with a default user, typing the password but without needing to insert the username. For instance, to prompt the password for username on tty1: 

/etc/systemd/system/getty@tty1.service.d/skip-username.conf
[Service]
ExecStart=
ExecStart=-/sbin/agetty -o '-p -- username' --noclear --skip-login - $TERM

Have boot messages stay on tty1

By default, Arch has the getty@tty1 service enabled. The service file already passes --noclear, which stops agetty from clearing the screen. However systemd clears the screen before starting it. To disable this behavior, create a drop-in file: 

/etc/systemd/system/getty@tty1.service.d/noclear.conf
[Service]
TTYVTDisallocate=no
Note:

See also