how to get the hostname when in single user mode

[curt larson_1]

is there a way to get the host when boot into single user mode, i.e. startup scripts haven't run so no networking available, and the /usr, etc. filesystems aren't mounted?

[Patrick Wallek · Accepted solution]

# grep "HOSTNAME=" /etc/rc.config.d/netconf

Remember that normally /etc is NOT a separate filesystem. It is under the / filesystem.

[Jeff Schussele]

Hi,

And if you mount /usr, you could run the hostname commnad.

Rgds,
Jeff

[A. Clay Stephenson]

I haven't knocked down to single user to test this but it should work:

echo "hostname/S" | adb /stand/vmunix /dev/kmem

[curt larson_1]

I had thought of using a file to save the name, but you have to keep that uptodate and there are other files that have the information, such as /etc/hosts.

And, Mr. Wallek has what I'm looking for a file where the there is only one entry and should be authoriative. althought grep is in /usr and unavailable, /sbin/awk should work just as well.

otherways, were writing a C program not using shared libraries. and the output from /sbin/uname -n, which is unknown in single user mode

[A. Clay Stephenson]

Forget mine, /usr has to be mounted for adb; it requires shared libraries.

[Sridhar Bhaskarla]

Just to add my 2 cents. "hostname" is set only during the rc scripts after the single user mode. So, even mounting /usr and other tricks may not help.

Patrick had the answer. That's the most possible hostname that would get assigned to the system later.

-Sri

[A. Clay Stephenson]

Okay, I have another method. We will ask the box ourselves with a statically linked program that you can install in /sbin.

-----------------------------------------
#include
#include

extern int errno;

int main()
{
int cc = 0;
char s[80];

cc = gethostname(s,(size_t) (sizeof(s) - 1));
if (cc == 0)
{
(void) printf("%s\n",s);
}
else
{
cc = (errno != 0) ? errno : -1;
(void) fprintf(stderr,"Gethostname failed. (%d)\n",cc);
}
return(cc);
}
--------------------------------------------

Compile gethostname.c like this (It will even compile with the Bundled compiler):

cc +DAportable -Wl,-a,archive -o gethostname gethostname.c

[Sijesh]

#cat /etc/rc.config.d/netconf and look for HOSTNAME=

else mount /usr (vgchange -a y /dev/vg00 ;mount /dev/vg00/lvol7 /usr)
then
#grep "HOSTNAME=" /etc/rc.config.d/netconf

[curt larson_1]

you can do this:
/sbin/awk '/HOSTNAME=/ {print;}' /etc/rc.config.d/netconf

but it returns lines and not really the value. And, with the possibilities of multiple lines, comments, and quoting, I think this works best for getting the value from netconf:

/sbin/sh -c ". /etc/rc.config.d/netconf;print $HOSTNAME"

Mr. Stephenson's program works. but it returns the same value as /sbin/uname -n would, i.e. it will report the hostname as "unknown" when in single user mode.

[Bill Hassell]

AS you've discovered, the hostname is meaningless (unknown) in songle user mode. That because hostname is of no value without networking. The hostname is assigned during startup from the /sbin/init.d/hostname file. In detail, it is set in run level 1 definitions (/sbin/rc1.d) just after mounts and some kernel init has been completed. So all systems have the same hostname in single user mode.