[mpich-discuss] importance of /tmp/mpd2.console_root?

[Ralph Butler]

On MonOct 6, at Mon Oct 6 12:17AM, Sangamesh B wrote:

> Hi,
>
>   In my case, the mpd was not running. mpdboot was giving problem  
> with mpd2.console_root file on that particular node.
> Tried to delete it. But it couldn't.

mpd has no particular magic to prevent a user from deleting a file  
which he/she owns.
If the file is owned by root, then root should be able to remove it,  
perhaps by changing the permissions first.
There might be an exception to this, e.g. in the case of a file in an  
nfs-mounted file system with some sort of
root-squash option turned on.  However, it is quite rare to have /tmp  
mounted via nfs.
In any case, the problem of how to delete an old file is a unix  
permissions issue.

>
> You r telling it will delete??
>
>   Rebooted that node. The strange thing happened is the node failed  
> to boot and stuck at GRUB prompt.
>
>  Then we reinstalled it. I'm not sure what is the exact cause for  
> this.
>
> Thanks,
> Sangamesh
> On Sat, Oct 4, 2008 at 8:16 AM, Rajeev Thakur <thakur at mcs.anl.gov>  
> wrote:
>
> From: Ralph Butler
> Sent: Friday, October 03, 2008 5:43 PM
> Subject: Re: [mpich-discuss] importance of /tmp/mpd2.console_root?
>
> A file in /tmp named mpd2.console_XXXX is a Unix socket.  It is used  
> by
> mpiexec (and other pgms) to connect to mpd.  Typically XXXX is the  
> name of a
> particular user who started the mpd and the socket can only be  
> connected to
> by that user.  However, if XXXX is root, and mpd was installed  
> correctly,
> then other users may connect to the socket and run jobs.  The socket  
> should
> be removed when the mpd exits gracefully, e.g. via mpdallexit.   
> However, it
> may be left when an mpd fails.  But an old file should be removed  
> when a new
> mpd starts.
>
>
> ________________________________
>
>        From: owner-mpich-discuss at mcs.anl.gov
> [mailto:owner-mpich-discuss at mcs.anl.gov] On Behalf Of Sangamesh B
>        Sent: Friday, October 03, 2008 1:22 AM
>        To: MPICH ML
>        Subject: [mpich-discuss] importance of /tmp/mpd2.console_root?
>
>
>        Hi all,
>
>             I want to know the importance of "mpd2.console_root" file.
>
>             This file gets created after launching the mpd's in /tmp
> directory.
>
>        srwxrwxrwx 1 root   root      0 Oct  3 11:21 mpd2.console_root
>
>             When mpd's are stopped, this file get deleted  
> automatically.
>
>        I'm curious to know about this because, recently I faced a  
> problem
> with mpdboot. mpdboot was not happening and gave error with a  
> particular
> node. I googled the error, then I came to know that its problem with  
> the
> above file.
>
>        Eventhough, there was no mpd(as user root) running on that  
> node, the
> file /tmp/mpd2.console_root was present. I tried to delete. But it  
> couldn't
> delete.
>
>        So why this file is required? In the above case what's the  
> wayout?
>
>        Thanks,
>        Sangamesh
>
>
>
>