Problem with PTY allocation

[Sandip Ghosh]

Mike,

If you look at the /dev/pts directory you will see that some of the devices are owned by root:sys and some of them are owned by the users. The pty's those are not used those will show you as root:sys, others are in use. In my system I could see that there are around 57/58 devices are there which is in use by some user. But when I am giving ps command I couldn't find those pty's.

By the fuser command I couldn't find any of them in use. I have looked through "last|grep still" command also. but I couldn't found any of them.

Sandip

[Mike Stroyan]

What does fuser say about /dev/ptmx ?

If there are rlogind or other master side processes holding /dev/ptmx open, then they could be keep the slave sides of the ptys busy even though no process has the slave side open.

That would fit the FINWAIT problem.

[Animesh Chakraborty]

Hi Sandip,
If you have glance then
#glance -t will show the used npty numbers.
You can also donload lsof to monitor the process being used.

Regards

[Sandip Ghosh]

Hi Mike,

It is not showing anything on /dev/ptmx.

Animesh,

It is showing available=60 and used=2. HP is also looking at the problem. The problem is that once it is allocating one terminal it is not releasing from the kernel when the users are getting out of the system.

So, how is life in Singapore? Everybody is fine over there?

Sandip

[Mike Stroyan]

| If you look at the /dev/pts directory you will see
| that some of the devices are owned by root:sys and
| some of them are owned by the users. The pty's
| those are not used those will show you as
| root:sys, others are in use. In my system I could
| see that there are around 57/58 devices are there
| which is in use by some user. But when I am
| giving ps command I couldn't find those pty's.

The ownership of /dev/pts/* files does not indicate whether they are currently in use. The ownership is often set when a stream pty starts to be used. There is no convention of changing the ownership when the pty is no longer in use. (The grantpt() function runs the /usr/lbin/chgpt program to give ownership to the current user of the pty.)

Perhaps you are looking at the system when the problem is not occuring at all. You may have to wait for an "Unable to allocate pty" message before you run the fuser command to look for the cause of the trouble.