PHP Cookbook

19.2. Getting File Information

Problem

You want to read a file’s metadata; for example, permissions and ownership.

Solution

Use stat( ) , which returns an array of information about a file:

$info = stat('harpo.php');

Discussion

The function stat( ) returns an array with both numeric and string indexes with information about a file. The elements of this array are in Table 19-3.

Table 19-3. Information returned by stat( )

Numeric index	String index	Value
0	dev	Device
1	ino	Inode
2	mode	Permissions
3	nlink	Link count
4	uid	Owner’s user ID
5	gid	Group’s group ID
6	rdev	Device type for inode devices (-1 on Windows)
7	size	Size (in bytes)
8	atime	Last access time (epoch timestamp)
9	mtime	Last change time of contents (epoch timestamp)
10	ctime	Last change time of contents or metadata (epoch timestamp)
11	blksize	Block size for I/O (-1 on Windows)
12	blocks	Number of block allocated to this file

The mode element of the returned array contains the permissions expressed as a base 10 integer. This is confusing since permissions are usually either expressed symbolically (e.g., ls’s -rw-r--r-- output) or as an octal integer (e.g., 0644). To convert the permissions to a more understandable format, use base_convert( ) to change the permissions to octal:

$file_info = stat('/tmp/session.txt');
$permissions = base_convert($file_info['mode'],10,8);

This results in a six-digit octal number. For example, ...