文件状态信息

文件状态信息

例1:

mystat.c

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <sys/stat.h>
#include <unistd.h>
#include <sys/types.h>
#include <errno.h>

#define ERROR(flag)                 \
if(flag)                \
{                    \
printf("%d: ",__LINE__);    \
fflush(stdout);            \
perror("error");        \
exit(errno);            \
}
int main(int argc, char *argv[])
{
struct stat buf;

if (argc != 2)
{
printf("Usage: my_stat <filename>\n");
exit(0);
}

int ret = stat(argv[1], &buf);
ERROR(ret == -1);

printf("device is:                 %d\n", buf.st_dev);
printf("inode is:                 %d\n", buf.st_ino);
printf("mode is:                 %o\n", buf.st_mode);
printf("number of hard links  is:         %d\n", buf.st_nlink);
printf("user ID of owner is:             %d\n", buf.st_uid);
printf("group ID of owner is:             %d\n", buf.st_gid);
printf("device type (if inode device) is:     %d\n", buf.st_rdev);

printf("total size, in bytes is:         %d\n", buf.st_size);
printf(" blocksize for filesystem I/O is:    %d\n", buf.st_blksize);
printf("number of blocks allocated is:         %d\n", buf.st_blocks);

printf("time of last access is:         %s", ctime(&buf.st_atime));
printf("time of last modification is:         %s", ctime(&buf.st_mtime));
printf("time of last change is:         %s", ctime(&buf.st_ctime));

return 0;
}

编译/链接/执行后, 输出结果如下:



观察输出结果, 与前面的命令的输出结果一致

例2: chmod接口API

mychmod.c

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>

#define ERROR(flag)                 \
if(flag)                \
{                    \
printf("%d: ",__LINE__);    \
fflush(stdout);            \
perror("error");        \
exit(errno);            \
}

int main(int argc, char ** argv)
{
int    mode;
int    mode_u;
int    mode_g;
int    mode_o;

mode = atoi(argv[1]);

mode_u = mode / 100;
mode_g = (mode - (mode_u*100)) / 10;
mode_o = mode - (mode_u*100) - (mode_g*10);

mode = (mode_u * 8 * 8) + (mode_g * 8) + mode_o;

int ret = chmod(argv[2], mode);

ERROR(ret == -1);

return 0;
}

编译链接执行, 输出结果如下:



文件的读写等属性发生改变

例3: chown接口API

mychown.c

#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <fcntl.h>

#define ERROR(flag)                 \
if(flag)                \
{                    \
printf("%d: ",__LINE__);    \
fflush(stdout);            \
perror("error");        \
exit(errno);            \
}

int main(int argc,char *argv[])
{

//int ret = chown(argv[1],500,500);
int ret = chown(argv[1],7,7);

ERROR(ret == -1);

return 0;
}

编译链接执行, 结果输出如下:



文件的拥有者属性发生变化