umask

umask函数为进程设置文件模式创建屏蔽字，并返回以前的值。

＃include

mode_t umask(mode_t cmask)

example:

#include

#include

#include

#define RWRWRW (S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH)

int main()

{

    int value = umask(1);

    printf("value last time = %d\n", value);

    if (creat("foo", RWRWRW) < 0)

        printf("create errno for foo ");

    value = umask(S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);

    printf("value last time = %d\n", value);

    if (creat("bar", RWRWRW) < 0)

        printf("create errno for bar");

    exit(0);

    return 0;

}

result:

value last time = 18

value last time = 1

#ls -l

-rw------- 1 root      root         0 2010-04-28 16:49 bar

-rw-rw-rw- 1 root      root         0 2010-04-28 16:49 foo