Stat (Unix)
From Wikipedia, the free encyclopedia
stat() is a Unix system call that returns useful data about an inode. The semantics of stat() vary between operating systems. With Unix command ls, you can gather information about
- mtime: time of last modification (
ls -l), - ctime: time of last status change (
ls -lc) and - atime: time of last access (
ls -lu).
Note, that ctime is not the time of file creation. Overwriting a file changes mtime, ctime as well as atime. A change in file permissions or file ownership changes ctime and atime. Reading a file changes atime.
[edit] Synopsis
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
int stat(const char *filename, struct stat *buf);
int lstat(const char *filename, struct stat *buf);
int fstat(int filedesc, struct stat *buf);
struct stat {
dev_t st_dev; /* device */
ino_t st_ino; /* inode */
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 type (if inode device) */
off_t st_size; /* total size, in bytes */
blksize_t st_blksize; /* blocksize for filesystem 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 */
};
[edit] In Perl
In the platform-independent scripting language Perl, stat() returns a thirteen-element array. From the Perl documentation:
Not all fields are supported on all filesystem types. Here are the meaning of the fields: 0 dev device number of filesystem 1 ino inode number 2 mode file mode (type and permissions) 3 nlink number of (hard) links to the file 4 uid numeric user ID of file's owner 5 gid numeric group ID of file's owner 6 rdev the device identifier (special files only) 7 size total size of file, in bytes 8 atime last access time in Unix time format 9 mtime last modify time in Unix time format 10 ctime inode change time (NOT creation time!) in Unix time format 11 blksize preferred block size for file system I/O 12 blocks actual number of blocks allocated
