sys/stat.h

<sys/stat.h> is the header in the C POSIX library for the C programming language that contains constructs that facilitate getting information about files attributes.

Member functions

Member constants

The following POSIX macros are defined to check the file type using the st_mode field:

The following flags are defined for the st_mode field:

The set-group-ID bit (S_ISGID) has several special uses. For a directory it indicates that BSD semantics is to be used for that directory: files created there inherit their group ID from the directory, not from the effective group ID of the creating process, and directories created there will also get the S_ISGID bit set. For a file that does not have the group execution bit (S_IXGRP) set, the set-group-ID bit indicates mandatory file/record locking. The sticky bit (S_ISVTX) on a directory means that a file in that directory can be renamed or deleted only by the owner of the file, by the owner of the directory, and by a privileged process.

POSIX does not describe the S_IFMT, S_IFSOCK, S_IFLNK, S_IFREG, S_IFBLK, S_IFDIR, S_IFCHR, S_IFIFO, S_ISVTX bits, but instead demands the use of the macros S_ISDIR(), etc. The S_ISLNK() and S_ISSOCK() macros are not in POSIX.1-1996, but both are present in POSIX.1-2001; the former is from SVID 4, the latter from SUSv2.

Other Systems - Values that have been (or are) in use on various systems:

A sticky command appeared in Version 32V AT&T UNIX.

Member types

Data types defined in the <sys/stat.h> header include:

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 file system I/O */
  blkcnt_t  st_blocks;  /* number of blocks allocated */
  time_t    st_atime;   /* time of last access */
  time_t    st_mtime;   /* time of last modification */
  time_t    st_ctime;   /* time of last status change */
};

Example

A short example of <sys/stat.h> usage is:

/**************************************************************
 abstract ls meaning
 **************************************************************/
#include <stdio.h>
#include <sys/stat.h>
#include <string.h>
#include <errno.h>
 
int            main(int argc, char **argv)
{
  struct stat  file_stat;
 
  while (argc-- > 1)
    {
      if (lstat(argv[argc], &file_stat) == -1)
        fprintf(stderr, "%s\n", strerror(errno));
      else
        {
          fprintf(stdout, "Links\tUid\tGid\tSize\tName\n");
          fprintf(stdout, "%u\t%u\t%u\t%u\t%s\n", file_stat.st_nlink,
                  file_stat.st_uid, file_stat.st_gid, file_stat.st_size,
                  argv[argc]);
        }
    }
  return 0;
}

Put the source in a file (main.c) and compile this:

 gcc main.c -o test

Now, to run type:

 ./test main.c
 ./test *

References

• Gnu File Attributes