Output Redirection

Since batch jobs do not have a terminal connection, their standard output and their standard error output must be redirected into files. The grid engine system enables the user to define the location of the files to which the output is redirected. Defaults are used if no output files are specified.

The standard location for the files is in the current working directory where the jobs run. The default standard output file name is job-name.ojob-id, the default standard error output is redirected to job-name>.ejob-id. The job-name can be built from the script file name, or defined by the user. See, for example, the -N option in the submit(1) man page. job-id is a unique identifier that is assigned to the job by the grid engine system.

For array job tasks , the task identifier is added to these filenames, separated by a dot. The resulting standard redirection paths are job-name.ojob-id.task-id> and job-name.ejob-id.task-id. For more information, see Submitting Array Jobs.

In case the standard locations are not suitable, the user can specify output directions with QMON, as shown in Figure 3–6. Or the user can use the -e and -o options to the qsub command to specify output directions. Standard output and standard error output can be merged into one file. The redirections can be specified on a per execution host basis, in which case, the location of the output redirection file depends on the host on which the job is executed. To build custom but unique redirection file paths, use dummy environment variables together with the qsub -e and -o options. A list of these variables follows.

• HOME – Home directory on execution machine

• USER – User ID of job owner

• JOB_ID – Current job ID

• JOB_NAME – Current job name; see the -N option

• HOSTNAME – Name of the execution host

• TASK_ID – Array job task index number

When the job runs, these variables are expanded into the actual values, and the redirection path is built with these values.

See the qsub(1) man page for further details.