
A
Examples
This appendix provides examples that illustrate how to buil d a nd run applicati ons on the HP X C
system. The examples in this section show you how to take advantage of some of the many
methods available, and demonstrate a variety of other user commands to monitor, control, or
kill jo bs.
The examples in this section assume that yo u have read the information in previous chapters
describing how to use the HP XC comm a nds to build and run parallel applications. Only
examples of building and running applications are provided in this section — detailed
information about the commands is not provided.
A.1 Building and Running a Serial Application
This example s how how to build a simple appli cation, called hello world, and launch it
with the SLU RM srun command.
The f ollow ing is the source code for the hello world program, located in file
hw_hostname.c.
#include <unistd.h>
#include <stdio.h>
int main()
{
char name[100];
gethostname(name, sizeof(name));
printf("%s says Hello!\n", name);
return 0;
}
The hello world program is compiled in the usual way:
$ cc hw_hostname.c -o hw_hostname
When run on the login node, it shows the name of the login node; n16 in this case:
$ ./hw_hostname
n16 says Hello!
srun can b e used to run it on one of the compute nodes. This time it lands on n13:
$ srun ./hw_hostname
n13 says Hello!
srun can also be used to replicate it on several com pute nodes. This is not generally useful, but
is included for illustrative purposes.
$ srun -n4 ./hw_hostname
n13 says Hello!
n13 says Hello!
n14 says Hello!
n14 says Hello!
A.2 Launching a Serial Interactive Shell Through LSF
This section provides an example that shows how to launch a serial interactive shell through
LSF. The bsub -Is comm and is used to launch an interactive shell through LSF. This example
Examples A-1
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