QLIMIT(1)

NAME
qlimit - show supported batch limits, and shell strategy for the named host(s).

SYNOPSIS
qlimit [ -v ] [ host-name ... ]

DESCRIPTION
Qlimit displays the set of batch request resource limit types that can be directly enforced on the implied local host or named hosts, and also the batch request shell strategy defined for the implied local host or named hosts.

If no host-names are given, then the information displayed is only relevant to the local host. Otherwise, the supported batch request limits, and batch request shell strategy for each of the named hosts is displayed.

The -v switch indicates that the version of the program is to be printed.

NQS supports many batch request resource limit types that can be applied to an NQS batch request. However, not all UNIX implementations are capable of supporting the rather extensive set of limit types that NQS provides.

The set of limits applied to a batch request, is always restricted to the set of limits that can be directly supported by the underlying UNIX implementation. If a batch request specifies a limit that cannot be enforced by the underlying UNIX implementation, then the limit is simply ignored, and the batch request will operate as though there were no limit (other than the obvious physical maximums), placed upon that resource type.

When an attempt is made to queue a batch request, each limit-value specified by the request (that can also be supported by the local UNIX implementation), is compared against the corresponding limit-value as configured for the destination batch queue. If the corresponding batch queue limit-value for all batch request limit-values is defined as unlimited, or is greater than or equal to the corresponding batch request limit-value, then the request can be successfully queued, provided that no other anomalous conditions occur. For request infinity limit-values, the corresponding queue limit-value must also be configured as infinity.

These resource limit checks are performed irrespective of the batch request arrival mechanism, either by a direct use of the qsub(1) command, or by the indirect placement of a batch request into a batch queue via a pipe queue. It is impossible for a batch request to be queued in an NQS batch queue if any of these resource limit checks fail.

Finally, if a request fails to specify a limit-value for a resource limit type that is supported on the execution machine, then the corresponding limit-value as configured for the destination queue, becomes the limit-value for the unspecified request limit.

Upon the successful queueing of a request in a batch queue, the set of limits under which the request will execute is frozen, and will not be modified by subsequent qmgr(1M) commands that alter the limits of the containing batch queue.

As mentioned above, this command also displays the shell strategy as configured for the implied local host, or named hosts. In the absence of a shell specification for a batch request, NQS must choose which shell should be used to execute that batch request. NQS supports three different algorithms, or strategies to solve this problem that can be configured for each system by a system administrator, depending on the needs of the user's involved, and upon system performance criterion.

The three possible shell strategies are called:

        fixed,
        free, and
        login.

These shell strategies respectively cause the configured fixed shell to be exec'd to interpret all batch requests, cause the user's login shell as defined in the password file to be exec'd which in turn chooses and spawns the appropriate shell for running the batch shell script, or cause only the user's login shell to be exec'd to interpret the script.

A shell strategy of fixed means that the same shell as chosen by the system administrator, will be used to execute all batch requests.

A shell strategy of free will run the batch request script exactly as would an interactive invocation of the script, and is the default NQS shell strategy.

The strategies of fixed, and login exist for host systems that are short on available free processes. In these two strategies, a single shell is exec'd, and that same shell is the shell that executes all of the commands in the batch request shell script.

When a shell strategy of fixed has been configured for a particular NQS system, then the "fixed" shell that will be used to run all batch requests at that host is displayed.

SEE ALSO
qdel(1), qdev(1), qpr(1), qstat(1), and qsub(1) in the NPSN UNIX System Programmer Reference Manual.
qmgr(1M) in the NPSN UNIX System Administrator Reference Manual.

NPSN HISTORY
Origin: Sterling Software Incorporated

May 1986 - Brent Kingsbury, Sterling Software
Original release.

August, 1994 - John Roman, Monsanto Company
Version 3.36