The stat and Access functions under Linux

1.stat has both a command and a function of the same name, used to obtain the main information in the Inode (i.e. file type, file permissions, creation/modification/access time, etc.), stat tracking Symbolic Links, lstat not tracking symbolic links. You can view related information through Man 2 Stat.

 #include <sys/types.h> #include <sys/stat.h> #include <unistd.h>int stat (const char *path, struct stat      *BUF) int fstat (int fd, struct stat *buf), int lstat (const char *path, struct stat *buf); struct Stat {dev_t     St_dev;     /* ID of device containing file */ino_t St_ino;    /* inode number */mode_t st_mode;   /* Protection */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;  /* BlockSize for filesystem I/O */blkcnt_t st_blocks;   /* Number of 512B blocks allocated */time_t st_atime;   /* Time of last access */time_t st_mtime; /* Time of last modification *//refers to the modificationDocument Content time_t St_ctime; /* Time of last status change *//refers to modify Inode property};

#include <sys/types.h> #include <sys/stat.h> #include <time.h> #include <unistd.h> #include <errno.h> #include <stdio.h>int main (int argc, char *argv[]) {struct stat filestat;if (ARGC < 2) {printf (" Usage:%s <pathname>\n ", argv[0]); return 0;} if (stat (argv[1], &filestat) = =-1) {perror ("Stat error:"); return 0;} printf ("File type:"); switch (Filestat.st_mode & s_ifmt)//0170000 bit mask for the File type bit fie Lds{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) Filestat.st_ino);p rintf ("Mode:%lo (octal) \ n", (unsign Ed long) Filestat.st_mode);p rintf ("Link count:%ld\n", (lONG) filestat.st_nlink);p rintf ("Ownership:uid=%ld gid=%ld\n", (Long) Filestat.st_uid, (long) filestat.st_ GID);p rintf ("Preferred I/O block size:%ld bytes\n", (long) filestat.st_blksize);p rintf ("File Size:%lld by Tes\n ", (Long Long) filestat.st_size);p rintf (" Blocks Allocated:%lld\n ", (Long Long) filestat.st_blocks);p rintf (" L AST status change:%s ', CTime (&filestat.st_ctime));p rintf ("Last File access:%s", CTime (&filestat.st _atime));p rintf ("Last File Modification:%s", CTime (&filestat.st_mtime)); return 0;}

2.access function

Function: Determines the access rights for a file or folder. That is, check how a file is accessed, such as read-only, write-only, and so on. If the specified access method is valid, the function returns 0, otherwise the function returns-1.

#include <unistd.h>int access (const char *pathname, int mode);

Test by actual user ID and actual group ID, track symbolic links
Parameter mode
R_ok whether read access is available
W_ok whether there is write permission
X_ok whether there is execute permission
F_OK testing whether a file exists

#include <stdio.h> #include <unistd.h>int main (int argc, char *argv[]) {if (ARGC < 2) {printf ("Usage:%s < Pathname>\n ", argv[0]); return 0;} if (Access (argv[1],r_ok| x_ok| W_OK) {==0) {printf ("read Wirte execute \ n");} return 0;}

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The stat and Access functions under Linux