TTY Autologin

2024-06-23T17:26:22Z

Sewn: Add note for setting permission bit for script

=By using agetty=

== How ==
Install {{pkg|agetty}}: {{cmd|# apk add agetty}}
Edit {{path|/etc/inittab}} to use agetty 
Example for the virtual terminal tty1: 
<code>tty1::respawn:/sbin/agetty --autologin root tty1 linux</code>

Example inittab entry for a serial terminal on ttys01: 
<code>ttyS0::respawn:/sbin/agetty --autologin root ttyS0 vt100</code>
{{tip|You can change the `tty1` or `ttyS0` to a different serial port or virtual terminal as you please. `root` can be changed to a different user as well. Finally the terminal type (`linux` and `vt100` in our examples) can be changed to a wide variety of serial terminals.}}

=By making your own autologin wrapper=

== How ==
# Writing a wrapper script, called autologin, around {{path|/bin/login}} and moving it in {{path|/usr/sbin/}}
# Editing {{path|/etc/inittab}} specifying the use of {{path|/usr/sbin/autologin}} instead of {{path|/bin/login}}

== Writing the autologin script ==

Edit and create the script in this example in the location {{path|/usr/sbin/autologin}}:

{{cat|/usr/sbin/autologin|#!/bin/sh
exec login -f root}}

Remember to make the scripts executable:
{{cmd|# chmod +x /usr/sbin/autologin}}

The script executes the ''login'' binary (part of busybox) which will be searched in $PATH.

As parameters are passed:
* '''-f''' flag which stands for "Do not authenticate (user already authenticated)"
* ''username'' in this example is ''root'' but if you created a new user, its username can be used instead.

== Editing /etc/inittab ==

Open {{path|/etc/inittab}}

replace "'':respawn:/sbin/getty''" with "'':respawn:/sbin/getty -n -l /usr/sbin/autologin''" for each TTY you want to enable autologin.
* The getty's '''-n''' flag do not prompt the user for a login name
* The getty's '''-l''' flag invokes a custom login instead of {{path|/bin/login}}; in our case it is set to invoke {{path|/usr/sbin/autologin}}

==== Note ====
To perform such a replacement on all TTYs, the following command can be used:
{{Cmd|# sed -i 's@:respawn:/sbin/getty@:respawn:/sbin/getty -n -l /usr/sbin/autologin@g' /etc/inittab }}
* "'''@'''" is used as a delimiter
* The '''-i''' flag edits the file in-place

== References ==
* [https://git.busybox.net/busybox/tree/init/init.c Busybox init source, substantial comments documenting /etc/inittab are at the bottom]
* [http://littlesvr.ca/linux-stuff/articles/autologinconsole/autologinconsole.php Linux-Stuff: Log in automatically to a console when Linux boots]
* [https://wiki.gumstix.com/index.php/AutoLogin AutoLogin - Gumstix User Wiki]
* [https://busybox.net/downloads/BusyBox.html#getty Busybox getty arguments]
* [https://github.com/util-linux/util-linux/blob/master/term-utils/agetty.8.adoc agetty(8) Manual Page]

TTY Autologin

2024-06-23T17:23:04Z

Sewn: Avoid making a C program and just use a script

=By using agetty=

== How ==
Install {{pkg|agetty}}: {{cmd|# apk add agetty}}
Edit {{path|/etc/inittab}} to use agetty 
Example for the virtual terminal tty1: 
<code>tty1::respawn:/sbin/agetty --autologin root tty1 linux</code>

Example inittab entry for a serial terminal on ttys01: 
<code>ttyS0::respawn:/sbin/agetty --autologin root ttyS0 vt100</code>
{{tip|You can change the `tty1` or `ttyS0` to a different serial port or virtual terminal as you please. `root` can be changed to a different user as well. Finally the terminal type (`linux` and `vt100` in our examples) can be changed to a wide variety of serial terminals.}}

=By making your own autologin wrapper=

== How ==
# Writing a wrapper script, called autologin, around {{path|/bin/login}} and moving it in {{path|/usr/sbin/}}
# Editing {{path|/etc/inittab}} specifying the use of {{path|/usr/sbin/autologin}} instead of {{path|/bin/login}}

== Writing the autologin script ==

Edit and create the script in this example in the location {{path|/usr/sbin/autologin}}:

{{cat|/usr/sbin/autologin|#!/bin/sh
exec login -f root}}

The script executes the ''login'' binary (part of busybox) which will be searched in $PATH.

As parameters are passed:
* '''-f''' flag which stands for "Do not authenticate (user already authenticated)"
* ''username'' in this example is ''root'' but if you created a new user, its username can be used instead.

== Editing /etc/inittab ==

Open {{path|/etc/inittab}}

replace "'':respawn:/sbin/getty''" with "'':respawn:/sbin/getty -n -l /usr/sbin/autologin''" for each TTY you want to enable autologin.
* The getty's '''-n''' flag do not prompt the user for a login name
* The getty's '''-l''' flag invokes a custom login instead of {{path|/bin/login}}; in our case it is set to invoke {{path|/usr/sbin/autologin}}

==== Note ====
To perform such a replacement on all TTYs, the following command can be used:
{{Cmd|# sed -i 's@:respawn:/sbin/getty@:respawn:/sbin/getty -n -l /usr/sbin/autologin@g' /etc/inittab }}
* "'''@'''" is used as a delimiter
* The '''-i''' flag edits the file in-place

== References ==
* [https://git.busybox.net/busybox/tree/init/init.c Busybox init source, substantial comments documenting /etc/inittab are at the bottom]
* [http://littlesvr.ca/linux-stuff/articles/autologinconsole/autologinconsole.php Linux-Stuff: Log in automatically to a console when Linux boots]
* [https://wiki.gumstix.com/index.php/AutoLogin AutoLogin - Gumstix User Wiki]
* [https://busybox.net/downloads/BusyBox.html#getty Busybox getty arguments]
* [https://github.com/util-linux/util-linux/blob/master/term-utils/agetty.8.adoc agetty(8) Manual Page]

Alpine Linux - User contributions [en]

TTY Autologin

TTY Autologin