Login & Interactive Environment

Last modified: Friday September 07, 2012 10:40 AM


Use of the login nodes (eos1, eos2, eos3, eos4, and eos5) is intended for "small" processing only. This includes, but is not limited to, the tasks of compiling codes, testing and making short runs, batch job preparation and submission, and so on. The interactive CPU time limit per login session is 1 hour, while the maximum number of CPUs to engage for concurrent use is four (4) per user, whether that is through a single or through multiple logins. In particular, all parallel (OpenMP or MPI) program executions must NOT exceed the above CPU limit. Program runs that require extended CPU time and/or a higher (than 4) CPU counts should be submitted to the batch system.

You may view your login session limits with the ulimit -a command. The output below shows the typical output of the ulimit command for the bash shell, the default interactive shell on eos:

eos# ulimit -a
core file size          (blocks, -c) 0
data seg size           (kbytes, -d) 2097152  
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 409600
max locked memory       (kbytes, -l) unlimited
max memory size         (kbytes, -m) 2097152
open files                      (-n) 10000
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 10240
cpu time               (seconds, -t) 3600
max user processes              (-u) 409600
virtual memory          (kbytes, -v) 2097152
file locks                      (-x) unlimited

Login Environment

The default shell for eos is bash. This shell is recommended for batch processing. You must NOT copy startup files from other systems to your home directory on eos. Startup files copied from other systems are sometimes the cause of user problems.

The TMPDIR environment variable specifies a directory where temporary files should be placed. The default location for TMPDIR is /scratch/$USER/tmp for interactive sessions. Applications which use the TMPDIR variable will place temporary files created during execution in the TMPDIR directory. Unlike hydra, the TMPDIR variable is not set differently for batch jobs.

You can view all the variables in your environment with the command:

eos% env

In general, the environments for applications, compilers, libraries are managed with modules.

Startup Files

The startup files are read and executed by the login shell when you login to the cluster. Environment variables and aliases as well as other settings to be made persistent for all login sessions and batch jobs should be stored in your startup files. The following files are provided in your home directory upon account creation:

Any commands in this file are executed upon a login for the bash shell.
Any commands in this file are executed each time an interactive non-login bash shell starts.

Viewing Man Pages

Information can be found for almost any command in the command's online manual page (commonly referred to as a man page). The following shows how to view the man page for the ls command.

eos# man ls

More information about using man pages can be found here..