内容简介
#include <unistd.h>int nice(int%uA0inc)
描述
nice()%uA0增加inc%uA0为调用进程的nice值. (A higher nice value means a low priority.) Only the super%uA0user may specify a negative increment, or priority increase. The range for nice values is described in%uA0getpriority(2).返回值
On success, the new nice value is returned (but see NOTES below). On error, -1 is returned, and%uA0errno%uA0is set appropriately.错误
| 标签 | 描述 |
|---|---|
| EPERM | The calling process attempted to increase its priority by supplying a negative%uA0inc%uA0but has insufficient privileges. Under Linux the%uA0CAP_SYS_NICEꃊpability is required. (But see the discussion of the%uA0RLIMIT_NICE%uA0resource limit in%uA0setrlimit(2).) |
遵循于
SVr4, 4.3BSD, POSIX.1-2001. However, the Linux and (g)libc (earlier than glibc 2.2.4) return value is nonstandard, see below. SVr4 documents an additional EINVAL error code.注意
SUSv2 and POSIX.1-2001 specify that%uA0nice() should return the new nice value. However, the Linux syscall and the%uA0nice() library function provided in older versions of (g)libc (earlier than glibc 2.2.4) return 0 on success. The new nice value can be found usinggetpriority(2).Since glibc 2.2.4,%uA0nice() is implemented as a library function that calls%uA0getpriority(2) to obtain the new nice value to be returned to the caller. With this implementation, a successful call can legitimately return -1. To reliably detect an error, set%uA0errno%uA0to 0 before the call, and check its value when%uA0nice() returns -1.