TTY Autologin

What follows is one from many different ways to get autologin.

How

Writing a wrapper, called autologin, around /bin/login and moving it in /usr/sbin/
Editing /etc/inittab specifying the use of /usr/sbin/autologin instead of /bin/login

Create a file; in this example called autologin.c

# vi autologin.c

Write into it the following C program.

#include <unistd.h> int main() { execlp( "login", "login", "-f", "root", 0); }

The only thing it does is a system call to execute 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, the user username can be used instead.

If using tcc:

# tcc -o autologin autologin.c

Move the binary autologin to /usr/sbin

# mv autologin /usr/sbin/

# sed -i 's@:respawn:/sbin/getty@:respawn:/sbin/getty -n -l /usr/sbin/autologin@g' /etc/inittab

The above command:

replaces ":respawn:/sbin/getty" with ":respawn:/sbin/getty -n -l /usr/sbin/autologin"
"@" is used as a delimiter
The -i flag edits the file in-place
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 /bin/login; in our case it is set to invoke /usr/sbin/autologin

It is possible to remove the autologin.c file, the C compiler and the musl-dev package

# rm autologin.c # apk del tcc # apk del musl-dev