prototype

stat, fstat, lstat - get file status

SYNOPSIS

include 
include 


int stat(const char *file_name, struct stat *buf);
int fstat(int filedes, struct stat *buf);
int lstat(const char *file_name, struct stat *buf);

DESCRIPTION

These functions return information about the specified file. You do not need any access rights to the file to get this information but you need search rights to all directories named in the path leading to the file.

• stat stats the file pointed to by file_name and fills in buf.
• lstat is identical to stat, only the link itself is stated, not the file that is obtained by tracing the links.
• fstat is identical to stat, only the open file pointed to by filedes (as returned by [fopen()]) is stated in place of file_name.

They all return a stat structure, which is declared as follows:

struct stat {
    dev_t         st_dev;      /* device */
    ino_t         st_ino;      /* inode */
    umode_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 type (if inode device) */
    off_t         st_size;     /* total size, in bytes */
    unsigned long st_blksize;  /* blocksize for filesystem I/O */
    unsigned long 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 change */
};

Note that st_blocks may not always be in terms of blocks of size st_blksize, and that st_blksize may instead pro- vide a notion of the "preferred" blocksize for efficient file system I/O.

Not all of the Linux filesystems implement all of the time fields. Traditionally, st_atime is changed by mknod(2), utime(2), read(2), write(2), and truncate(2).

Traditionally, st_mtime is changed by mknod(2), utime(2), and write(2). The st_mtime is not changed for changes in owner, group, hard link count, or mode.

Traditionally, st_ctime is changed by writing or by setting inode information (i.e., owner, group, link count, mode, etc.).

The following macros are defined to check the file type:

• S_ISLNK(m) is it a symbolic link?
• S_ISREG(m) regular file?
• S_ISDIR(m) directory?
• S_ISCHR(m) character device?
• S_ISBLK(m) block device?
• S_ISFIFO(m) fifo?
• S_ISSOCK(m) socket?

The following flags are defined for the st_mode field:

• S_IFMT 00170000 bitmask for the file type bit-fields
• S_IFSOCK 0140000 socket
• S_IFLNK 0120000 symbolic link
• S_IFREG 0100000 regular file
• S_IFBLK 0060000 block device
• S_IFDIR 0040000 directory
• S_IFCHR 0020000 character device
• S_IFIFO 0010000 fifo
• S_ISUID 0004000 set UID bit
• S_ISGID 0002000 set GID bit
• S_ISVTX 0001000 sticky bit
• S_IRWXU 00700 user (file owner) has read, write and execute permission
• S_IRUSR (S_IREAD) 00400 user has read permission
• S_IWUSR (S_IWRITE) 00200 user has write permission
• S_IXUSR (S_IEXEC) 00100 user has execute permission
• S_IRWXG 00070 group has read, write and execute permission
• S_IRGRP 00040 group has read permission
• S_IWGRP 00020 group has write permission
• S_IXGRP 00010 group has execute permission
• S_IRWXO 00007 others have read, write and execute permission
• S_IROTH 00004 others have read permission
• S_IWOTH 00002 others have write permisson
• S_IXOTH 00001 others have execute permission

RETURN VALUE

On success, zero is returned. On error, -1 is returned, and errno is set appropriately.

ERRORS

• EBADF filedes is bad.
• ENOENT File does not exist.