usp - set POSIX control parameters dynamically

This command can only be issued by the superuser. The usp command has the following functions:

• Displays the current values of all POSIX control parameters (-s option).

• Modifies the current values of the following POSIX control parameters: DBLPOOL, FORCEDTERM, HDSTNI, HDPTNI, HEAPSZ, MAXTIMERC, MAXUP, NOSTTY, NOTTY and NPROC. Depending on the option specified (-p or -P), the modification is either only valid until the POSIX subsystem is terminated or also the next time POSIX is started.

• Checks whether a value specification is permitted for a selected control parameter (-c option).

Syntax

usp -h

usp -s[ parameter]

usp -c parameter -v value

usp -p parameter -v value

usp -P parameter -v value

-h

(h - help)

The syntax of the usp command and a list of all POSIX control parameters are output. In addition to the names and the meanings of the POSIX control parameters, this list also specifies whether the modification of a parameter is supported by the usp command (SUPPORTED) or not (unsupported).

-s

(s - show)

The current value of the control parameters specified with parameter is output. If parameter is not specified, the current values of all (supported and unsupported) control parameters are output.

parameter

Name of the control parameter. Only the control parameters DBLPOOL, FORCEDTERM, HDSTNI, HDPTNI, HEAPSZ, MAXTIMERC, MAXUP, NOSTTY, NOTTY and NPROC which can be modified with the support of the usp command can be specified using the -c, -p and -P options. All control parameters can be specified with the -s option. The specification can be in uppercase or lowercase characters. You can also obtain the information regarding whether or not the modification of a control parameter is supported by the usp command using usp -h.

-c

(c - check)

Checks whether the value specified using the -v option is within the limits permitted for parameter (minimum value <= value <= maximum value).

-p

The current value of the control parameter specified using parameter is replaced by the value specified using the -v option provided this value is legal (see the -c option). The condition (value > current value) must also be fulfilled for the following control parameters: HDSTNI, HDPTNI, HEAPSZ, MAXUP, NOSTTY, NOTTY and NPROC. The modification only applies for the current POSIX subsystem session. After the POSIX subsystem has been restarted, the value from the POSIX information file SYSSSI.POSIX-BC.<version> applies again.

A modification to the control parameter DBLPOOL only becomes effective the next time the posdbl command is issued. The contents of the global program cache are not saved. A combination of the usp and posdbl commands is therefore required to modify the size of the global program cache; for details on this, see the manual "POSIX Basics for Users and System Administrators" [1].

-P

(like -p option). The new value is also entered in the POSIX information file SYSSSI.POSIX-BC.<version> and consequently also applies after the POSIX subsystem has been restarted.

Before the modification is made in the POSIX information file, a backup copy is created with the name SYSSSI.POSIX-BC.<version>.SAVE.<date>.<time>.

-v value

(v -value) Specifies the value which is to be set or checked.

Hint

You are recommended to enter the modified values in the SYSSSI file (e.g. with the –P option) and to use them the next time the system is started. This makes it unnecessary to adjust them dynamically again during the system session.

When the maximum value HDPTNI (number of local file systems) is increased and used, the new value must be contained in the POSIX information file SYSSSI.POSIX-BC.<version> the next time POSIX is started. If more local file systems are entered in the management tables (e.g. /etc/vfstab) than the value in the POSIX information file permits, the start of the POSIX subsystem is aborted with an error.

All dynamic modifications to control parameters are documented by means of logging in POSIX. Each modification that is made to a value is documented on the console. In addition, all modifications are recorded in the POSIX file /var/adm/messages.