APUE学习(三)文件类型

一．文件类型

１．普通文件

２．目录文件

３．块特殊文件，有缓冲

４．字符文件，无缓冲

５．管道FIFO

６．套接字

７．符号连接

二．stat,lstat,fstat

       #include <sys/types.h>
       #include <sys/stat.h>
       #include <unistd.h>

       int stat(const char *pathname, struct stat *statbuf);
       int fstat(int fd, struct stat *statbuf);
       int lstat(const char *pathname, struct stat *statbuf);
       lstat()  is  identical to stat(), except that if pathname is a symbolic link, then it
       returns information about the link itself, not the file that it refers to.

       fstat() is identical to stat(), except that the file about which information is to be
       retrieved is specified by the file descriptor fd.
           struct stat {
               dev_t     st_dev;         /* ID of device containing file */
               ino_t     st_ino;         /* Inode number */
               mode_t    st_mode;        /* File type and mode */
               nlink_t   st_nlink;       /* Number of hard links */
               uid_t     st_uid;         /* User ID of owner */
               gid_t     st_gid;         /* Group ID of owner */
               dev_t     st_rdev;        /* Device ID (if special file) */
               off_t     st_size;        /* Total size, in bytes */
               blksize_t st_blksize;     /* Block size for filesystem I/O */
               blkcnt_t  st_blocks;      /* Number of 512B blocks allocated */

               /* Since Linux 2.6, the kernel supports nanosecond
                  precision for the following timestamp fields.
                  For the details before Linux 2.6, see NOTES. */

               struct timespec st_atim;  /* Time of last access */
               struct timespec st_mtim;  /* Time of last modification */
               struct timespec st_ctim;  /* Time of last status change */

           #define st_atime st_atim.tv_sec      /* Backward compatibility */
           #define st_mtime st_mtim.tv_sec
           #define st_ctime st_ctim.tv_sec
           };

#include <sys/types.h>

#include <sys/stat.h>

#include <time.h>

#include <stdio.h>

#include <stdlib.h>

#include <sys/sysmacros.h>

int

main( int argc, char *argv[])

{

struct stat sb;

if (argc != 2) {

fprintf(stderr, "Usage: %s <pathname> \n ", argv[ 0]);

exit(EXIT_FAILURE);

}

if ( lstat(argv[ 1], &sb) == - 1) {

perror( "lstat");

exit(EXIT_FAILURE);

}

printf( "ID of containing device: [%lx,%lx] \n ",

( long) major(sb. st_dev), ( long) minor(sb. st_dev));

printf( "File type: ");

switch (sb. st_mode & S_IFMT) {

case S_IFBLK: printf( "block device \n "); break;

case S_IFCHR: printf( "character device \n "); break;

case S_IFDIR: printf( "directory \n "); break;

case S_IFIFO: printf( "FIFO/pipe \n "); break;

case S_IFLNK: printf( "symlink \n "); break;

case S_IFREG: printf( "regular file \n "); break;

case S_IFSOCK: printf( "socket \n "); break;

default: printf( "unknown? \n "); break;

}

printf( "I-node number: %ld \n ", ( long) sb. st_ino);

printf( "Mode: %lo (octal) \n ",

( unsigned long) sb. st_mode);

printf( "Link count: %ld \n ", ( long) sb. st_nlink);

printf( "Ownership: UID=%ld GID=%ld \n ",

( long) sb. st_uid, ( long) sb. st_gid);

printf( "Preferred I/O block size: %ld bytes \n ",

( long) sb. st_blksize);

printf( "File size: %lld bytes \n ",

( long long) sb. st_size);

printf( "Blocks allocated: %lld \n ",

( long long) sb. st_blocks);

printf( "Last status change: %s", ctime(&sb. st_ctime));

printf( "Last file access: %s", ctime(&sb. st_atime));

printf( "Last file modification: %s", ctime(&sb. st_mtime));

exit(EXIT_SUCCESS);

}