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GETPRIORITY(2) FreeBSD System Calls Manual GETPRIORITY(2) NAME getpriority, setpriority -- get/set program scheduling priority LIBRARY Standard C Library (libc, -lc) SYNOPSIS #include <sys/time.h> #include <sys/resource.h> int getpriority(int which, int who); int setpriority(int which, int who, int prio); DESCRIPTION The scheduling priority of the process, process group, or user, as indi- cated by which and who is obtained with the getpriority() system call and set with the setpriority() system call. The which argument is one of PRIO_PROCESS, PRIO_PGRP, or PRIO_USER, and who is interpreted relative to which (a process identifier for PRIO_PROCESS, process group identifier for PRIO_PGRP, and a user ID for PRIO_USER). A zero value of who denotes the current process, process group, or user. The prio argument is a value in the range -20 to 20. The default priority is 0; lower priori- ties cause more favorable scheduling. The getpriority() system call returns the highest priority (lowest numer- ical value) enjoyed by any of the specified processes. The setpriority() system call sets the priorities of all of the specified processes to the specified value. Only the super-user may lower priorities. RETURN VALUES Since getpriority() can legitimately return the value -1, it is necessary to clear the external variable errno prior to the call, then check it af- terward to determine if a -1 is an error or a legitimate value. The setpriority() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error. ERRORS The getpriority() and setpriority() system calls will fail if: [ESRCH] No process was located using the which and who values specified. [EINVAL] The which argument was not one of PRIO_PROCESS, PRIO_PGRP, or PRIO_USER. In addition to the errors indicated above, setpriority() will fail if: [EPERM] A process was located, but neither its effective nor real user ID matched the effective user ID of the caller. [EACCES] A non super-user attempted to lower a process prior- ity. SEE ALSO nice(1), fork(2), renice(8) HISTORY The getpriority() system call appeared in 4.2BSD. FreeBSD 13.0 June 4, 1993 FreeBSD 13.0
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | HISTORY
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