[SOLVED] "/dev/tty: No such file or directory"

littlebigman · 07-05-2011, 05:37 AM

Hello

I'm trying to use Busybox's init on an appliance running uClinux, instead of the default simpleinit because Busybox's init unmounts partitions while simpleinit simply calls sync().

The issue I'm having, is that device nodes are created dynamically by /bin/mdev in /etc/rc... which seems to be called after the kernel has read /etc/inittab:

Code:

#/etc/inittab
# Startup the system
tty::sysinit:/bin/sh /etc/rc

# Set up a console shell
tty::respawn:/bin/login -f root

Code:

#/etc/rc
if [ -e /bin/mdev ] ; then
        echo /bin/mdev 2>/dev/null > /proc/sys/kernel/hotplug
        /bin/mdev -s 2> /dev/null
fi

As a result, the kernel can't launch a shell on tty:

Quote:

VFS: Mounted root (ext2 filesystem) on device 31:0.
Freeing unused kernel memory: 108k freed
can't open /dev/tty: No such file or directory
can't open /dev/tty: No such file or directory
Jan 1 00:00:16 (none) syslog.info syslogd started: BusyBox v1.16.2
...
process '/bin/login -f root' (pid 32) exited. Scheduling for restart.

It looks like a chicken and egg problem. Does someone know what to do?

Thank you.

Karl Godt · 07-05-2011, 05:55 AM

Code:

tty1::respawn:/sbin/getty -n -l /bin/autologinroot 38400 tty1

Note : "autologinroot" is a binary created especially for "Puppy Linux"
Puppy linux actually uses busybox init

but with

Code:

##tty5::respawn:/sbin/getty -n -l "login -f root" 38400 tty5

I had no luck .
Error messages I cannot remember for now .

To create devices :

Code:

# cat /proc/devices | grep tty

3 ttyp
4 tty
4 ttyS
5 /dev/tty
188 ttyUSB

Code:

# ls -l /dev/tty*

crw-r--r-- 1 root root 5, 0 2001-02-13 19:39 /dev/tty
crw-r--r-- 1 root root 4, 0 2001-02-13 19:55 /dev/tty0
crw------- 1 root root 4, 1 2011-07-05 05:27 /dev/tty1
crw-r--r-- 1 root root 4, 10 2001-02-14 12:58 /dev/tty10

to create it manually

Code:

mknod /dev/tty1 c 4 1

See also the man pages of these commands , ie

Code:

man inittab

or

Code:

man mknod

especially

Code:

getty --help

littlebigman · 07-05-2011, 06:07 AM

Thanks for the help.

So you're saying that, even though dev nodes are created dynamically by mdev, I should run "mknod /dev/tty1 c 4 1" so that the tty1 is created so that init is happy with what's in inittab?

Where should I put "mknod /dev/tty1 c 4 1"?

littlebigman · 07-05-2011, 06:50 AM

Found the solution: As the kernel command line included "console=ttyBF0,115200", the solution is two-fold:

1. Keep using "console" in the "sysinit" line, but
2. Use "ttyBF0" (not "tty") in the "respawn" line where we launch /bin/login

Code:

console::sysinit:/bin/sh /etc/rc

#BAD tty::respawn:/bin/login -f root
ttyBF0::respawn:/bin/login -f root

For some reason, /dev does include "tty" but Linux isn't happy about using it:

Quote:

process '/bin/login -f root' (pid 58) exited. Scheduling for restart.
can't open /dev/tty: No such device or address

HTH,