Jump to content United States-English
HP.com Home Products and Services Support and Drivers Solutions How to Buy
» Contact HP
More options
HP.com home
HP-UX Reference > N


HP-UX 11i Version 3: February 2007

Technical documentation

» Feedback
Content starts here

 » Table of Contents

 » Index


nice — change priority of a process


#include <unistd.h>

int nice(int priority_change);


nice() adds the value of priority_change to the nice value of the calling process. A process's nice value is a positive number for which a more positive value results in lower CPU priority.

A maximum nice value of 39 and a minimum nice value of 0 are imposed by the system. Requests for values above or below these limits result in the nice value being set to the corresponding limit.

If the calling process contains more than one thread or lightweight process (i.e., the process is multi-threaded) this function shall apply to all threads or lightweight processes in the calling process.

Security Restrictions

Some or all of the actions associated with this system call are subject to compartmental restrictions. See compartments(5) for more information about compartmentalization on systems that support that feature. Compartmental restrictions can be overridden if the process possesses the PRIV_COMMALLOWED privilege (COMMALLOWED). Processes owned by the superuser may not have this privilege. Processes owned by any user may have this privilege, depending on system configuration.

Some or all of the actions associated with this system call require the PRIV_OWNER (OWNER) and/or the PRIV_LIMIT (LIMIT) privileges. Processes owned by the superuser will have these privileges. Processes owned by other users may have privilege(s), depending on system configuration. See privileges(5) for more information about privileged access on systems that support fine-grained privileges.


Upon successful completion, nice() returns the new nice value minus 20. Otherwise, a value of -1 is returned and errno is set to indicate the error.

Note that nice() assumes a user process priority value of 20. If a user having appropriate privileges has changed the user process priority value to something less than 20, certain values for priority_change can cause nice() to return -1, which is indistinguishable from an error return.



nice() fails and does not change the nice value if priority_change is negative or greater than 40, and the effective user ID of the calling process is not a user having appropriate privileges.


nice(): AES, SVID2, SVID3, XPG2, XPG3, XPG4

Printable version
Privacy statement Using this site means you accept its terms Feedback to webmaster
© 1983-2007 Hewlett-Packard Development Company, L.P.