Removing old package for Linux Mint

To remove the orphaned dependencies using apt-get

# apt-get autoremove

To clean old versions of packages using apt-get

# apt-get autoclean

To remove all packages files from the acahe using apt-get
# apt-get clean

Installing Java Runtime Environment (JRE) from the command line on Linux Mint

If you are planning to install JRE and the web browser plugin, you will need to do the following:

# apt-get install sun-java6-jre sun-java6-plugin sun-java6-fonts

Prevent non-users from login into the system

Sometimes as administrator, you may need to some immediate repair work and need to prevent users from logging in immediately, you can easily do that by doing the following:

# touch /etc/nologin

If the file exists, only the root can gain accessnow

pbs node manipulation Revision

It has been a long time since I used torque. I though I pen down some common commands I will used

• pbsnodes -l (List node names and their state. If no state is specified, only nodes in the DOWN, OFFLINE, or UNKNOWN states are listed. Specifying a state string acts as an output filter. Valid state strings are "active", "all", "busy", "down", "free", "offline", "unknown", and "up". )
  
• pbsnodes -o (Add the OFFLINE state. This is different from being marked DOWN. OFFLINE prevents new jobs from running on the specified nodes. This gives the administrator a tool to hold a node out of service without changing anything else. The OFFLINE state will never be set or cleared automatically by pbs_server; it is purely for the manager or operator.)
  
• pbsnodes -c (Clear OFFLINE from listed nodes)
  
• pbsnodes -a (All attributes of a node or all nodes are listed. This is the default if no flag is given)
  

libibverbs: Warning: RLIMIT_MEMLOCK is 32768 bytes. This will severely limit memory registrations.

We are using OpenFarics for our HPC. According to the FAQ, "With OpenFabrics (and therefore the openib BTL component), you need to set the available locked memory to a large number (or better yet, unlimited) -- the defaults with most Linux installations are usually too low for most HPC applications that utilize OpenFabrics"

libibverbs: Warning: RLIMIT_MEMLOCK is 32768 bytes.
This will severely limit memory registrations.

For the solution, look here at http://www.open-mpi.org/faq/?category=openfabrics#ib-locked-pages
Or you can also look at my blog entry Encountering Segmentation Fault, Bus Error or No output