class File::Stat

Create a File::Stat object for the given file name (raising an exception if the file doesn’t exist).

Compares self and other, by comparing their modification times; that is, by comparing self.mtime and other.mtime.

Returns:

• -1, if self.mtime is earlier.

• 0, if the two values are equal.

• 1, if self.mtime is later.

• nil, if other is not a File::Stat object.

Examples:

stat0 = File.stat('README.md')
stat1 = File.stat('NEWS.md')
stat0.mtime         # => 2025-12-20 15:33:05.6972341 -0600
stat1.mtime         # => 2025-12-20 16:02:08.2672945 -0600
stat0 <=> stat1     # => -1
stat0 <=> stat0.dup # => 0
stat1 <=> stat0     # => 1
stat0 <=> :foo      # => nil

Class File::Stat includes module Comparable, each of whose methods uses File::Stat#<=> for comparison.

Returns the last access time for this file as an object of class Time.

File.stat("testfile").atime   #=> Wed Dec 31 18:00:00 CST 1969

Returns the birth time for stat.

If the platform doesn’t have birthtime, raises NotImplementedError.

File.write("testfile", "foo")
sleep 10
File.write("testfile", "bar")
sleep 10
File.chmod(0644, "testfile")
sleep 10
File.read("testfile")
File.stat("testfile").birthtime   #=> 2014-02-24 11:19:17 +0900
File.stat("testfile").mtime       #=> 2014-02-24 11:19:27 +0900
File.stat("testfile").ctime       #=> 2014-02-24 11:19:37 +0900
File.stat("testfile").atime       #=> 2014-02-24 11:19:47 +0900

Returns the native file system’s block size. Will return nil on platforms that don’t support this information.

File.stat("testfile").blksize   #=> 4096

Returns true if the file is a block device, false if it isn’t or if the operating system doesn’t support this feature.

File.stat("testfile").blockdev?    #=> false
File.stat("/dev/hda1").blockdev?   #=> true

Returns the number of native file system blocks allocated for this file, or nil if the operating system doesn’t support this feature.

File.stat("testfile").blocks   #=> 2

Returns true if the file is a character device, false if it isn’t or if the operating system doesn’t support this feature.

File.stat("/dev/tty").chardev?   #=> true

Returns the change time for stat (that is, the time directory information about the file was changed, not the file itself).

Note that on Windows (NTFS), returns creation time (birth time).

File.stat("testfile").ctime   #=> Wed Apr 09 08:53:14 CDT 2003

Returns an integer representing the device on which stat resides.

File.stat("testfile").dev   #=> 774

Returns the major part of File_Stat#dev or nil.

File.stat("/dev/fd1").dev_major   #=> 2
File.stat("/dev/tty").dev_major   #=> 5

Returns the minor part of File_Stat#dev or nil.

File.stat("/dev/fd1").dev_minor   #=> 1
File.stat("/dev/tty").dev_minor   #=> 0

Returns true if stat is a directory, false otherwise.

File.stat("testfile").directory?   #=> false
File.stat(".").directory?          #=> true

Returns true if stat is executable or if the operating system doesn’t distinguish executable files from nonexecutable files. The tests are made using the effective owner of the process.

File.stat("testfile").executable?   #=> false

Same as executable?, but tests using the real owner of the process.

Returns true if stat is a regular file (not a device file, pipe, socket, etc.).

File.stat("testfile").file?   #=> true

Identifies the type of stat. The return string is one of: file`'', directory'', ```characterSpecial”, blockSpecial`'', fifo'', ```link”, socket`'', or unknown`”.

File.stat("/dev/tty").ftype   #=> "characterSpecial"

Returns the numeric group id of the owner of stat.

File.stat("testfile").gid   #=> 500

Returns true if the effective group id of the process is the same as the group id of stat. On Windows, returns false.

File.stat("testfile").grpowned?      #=> true
File.stat("/etc/passwd").grpowned?   #=> false

Returns the inode number for stat.

File.stat("testfile").ino   #=> 1083669

Produce a nicely formatted description of stat.

File.stat("/etc/passwd").inspect
   #=> "#<File::Stat dev=0xe000005, ino=1078078, mode=0100644,
   #    nlink=1, uid=0, gid=0, rdev=0x0, size=1374, blksize=4096,
   #    blocks=8, atime=Wed Dec 10 10:16:12 CST 2003,
   #    mtime=Fri Sep 12 15:41:41 CDT 2003,
   #    ctime=Mon Oct 27 11:20:27 CST 2003,
   #    birthtime=Mon Aug 04 08:13:49 CDT 2003>"

Returns an integer representing the permission bits of stat. The meaning of the bits is platform dependent; on Unix systems, see stat(2).

File.chmod(0644, "testfile")   #=> 1
s = File.stat("testfile")
sprintf("%o", s.mode)          #=> "100644"

Returns the modification time of stat.

File.stat("testfile").mtime   #=> Wed Apr 09 08:53:14 CDT 2003

Returns the number of hard links to stat.

File.stat("testfile").nlink             #=> 1
File.link("testfile", "testfile.bak")   #=> 0
File.stat("testfile").nlink             #=> 2

Returns true if the effective user id of the process is the same as the owner of stat.

File.stat("testfile").owned?      #=> true
File.stat("/etc/passwd").owned?   #=> false

Returns true if the operating system supports pipes and stat is a pipe; false otherwise.

Returns an integer representing the device type on which stat resides. Returns nil if the operating system doesn’t support this feature.

File.stat("/dev/fd1").rdev   #=> 513
File.stat("/dev/tty").rdev   #=> 1280

Returns the major part of File_Stat#rdev or nil.

File.stat("/dev/fd1").rdev_major   #=> 2
File.stat("/dev/tty").rdev_major   #=> 5

Returns the minor part of File_Stat#rdev or nil.

File.stat("/dev/fd1").rdev_minor   #=> 1
File.stat("/dev/tty").rdev_minor   #=> 0

Returns true if stat is readable by the effective user id of this process.

File.stat("testfile").readable?   #=> true

Returns true if stat is readable by the real user id of this process.

File.stat("testfile").readable_real?   #=> true

Returns true if stat has the set-group-id permission bit set, false if it doesn’t or if the operating system doesn’t support this feature.

File.stat("/usr/sbin/lpc").setgid?   #=> true

Returns true if stat has the set-user-id permission bit set, false if it doesn’t or if the operating system doesn’t support this feature.

File.stat("/bin/su").setuid?   #=> true

Returns the size of stat in bytes.

File.stat("testfile").size   #=> 66

Returns nil if stat is a zero-length file, the size of the file otherwise.

File.stat("testfile").size?   #=> 66
File.stat(File::NULL).size?   #=> nil

Returns true if stat is a socket, false if it isn’t or if the operating system doesn’t support this feature.

File.stat("testfile").socket?   #=> false

Returns true if stat has its sticky bit set, false if it doesn’t or if the operating system doesn’t support this feature.

File.stat("testfile").sticky?   #=> false

Returns true if stat is a symbolic link, false if it isn’t or if the operating system doesn’t support this feature. As File::stat automatically follows symbolic links, symlink? will always be false for an object returned by File::stat.

File.symlink("testfile", "alink")   #=> 0
File.stat("alink").symlink?         #=> false
File.lstat("alink").symlink?        #=> true

Returns the numeric user id of the owner of stat.

File.stat("testfile").uid   #=> 501

If stat is readable by others, returns an integer representing the file permission bits of stat. Returns nil otherwise. The meaning of the bits is platform dependent; on Unix systems, see stat(2).

m = File.stat("/etc/passwd").world_readable?  #=> 420
sprintf("%o", m)                              #=> "644"

If stat is writable by others, returns an integer representing the file permission bits of stat. Returns nil otherwise. The meaning of the bits is platform dependent; on Unix systems, see stat(2).

m = File.stat("/tmp").world_writable?         #=> 511
sprintf("%o", m)                              #=> "777"

Returns true if stat is writable by the effective user id of this process.

File.stat("testfile").writable?   #=> true

Returns true if stat is writable by the real user id of this process.

File.stat("testfile").writable_real?   #=> true

Returns true if stat is a zero-length file; false otherwise.

File.stat("testfile").zero?   #=> false