Purdue University

cannot connect to X server / cannot open display

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You receive the following message after entering a command to bring up a graphical window

cannot connect to X server cannot open display

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This can happen due to multiple reasons:

1. Reason: Your SSH client software does not support graphical display by itself (e.g. SecureCRT or PuTTY).
   • Solution: Try using a client software like Thinlinc or MobaXterm as described in the SSH X11 Forwarding guide.

2. Reason: You did not enable X11 forwarding in your SSH connection.

   • Solution: If you are in a Windows environment, make sure that X11 forwarding is enabled in your connection settings (e.g. in MobaXterm or PuTTY). If you are in a Linux environment, try

     ssh -Y -l username hostname

3. Reason: If you are trying to open a graphical window within an interactive PBS job, make sure you are using the -X option with qsub after following the previous step(s) for connecting to the front-end. Please see the example in the Interactive Jobs guide.
4. Reason: If none of the above apply, make sure that you are within quota of your home directory.

bash: command not found

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You receive the following message after typing a command

bash: command not found

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This means the system doesn't know how to find your command. Typically, you need to load a module to do it.

qdel: Server could not connect to MOM 12345.hammer-adm.rcac.purdue.edu

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You receive the following message after attempting to delete a job with the qdel command

qdel: Server could not connect to MOM 12345.hammer-adm.rcac.purdue.edu

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This error usually indicates that at least one node running your job has stopped responding or crashed. Please forward the job ID to support, and staff can help remove the job from the queue.

bash: module command not found

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You receive the following message after typing a command, e.g. module load intel

bash: module command not found

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The system cannot find the module command. You need to source the modules.sh file as below

source /etc/profile.d/modules.sh

or

#!/bin/bash -i

1234.hammer-adm.rcac.purdue.edu.SC: line 12: 12345 Killed

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Your PBS job stopped running and you received an email with the following:

/var/spool/torque/mom_priv/jobs/1234.hammer-adm.rcac.purdue.edu.SC: line 12: 12345 Killed <command name>

Link to section 'Solution' of '1234.hammer-adm.rcac.purdue.edu.SC: line 12: 12345 Killed' Solution

This means that the node your job was running on ran out of memory to support your program or code. This may be due to your job or other jobs sharing your node(s) consuming more memory in total than is available on the node. Your program was killed by the node to preserve the operating system. There are two possible causes:

• You requested your job share node(s) with other jobs. You should request all cores of the node or request exclusive access. Either your job or one of the other jobs running on the node consumed too much memory. Requesting exclusive access will give you full control over all the memory on the node.
• Your job requires more memory than is available on the node. You should use more nodes if your job supports MPI or run a smaller dataset.