Each file has three dates associated with it (stored as the number of seconds since the epoch, Jan 1, 1970). The three timestamps are

• Access time (atime) - the last time the file was read
• Modify time (mtime) - the last time the file contents were changed
• Change time (ctime) - the last time the file permissions were changed

 

In a long directory listing, the timestamp shown is the Modify time (mtime). To see all timestamps, use:
stat filename

Here is sample output from stat:

  File: `apache.php'
  Size: 9791            Blocks: 24         IO Block: 4096   Regular File
Device: 302h/770d       Inode: 1818841     Links: 1
Access: (0644/-rw-r--r--)  Uid: (32045/ wileyjb)   Gid: (32045/ wileyjb)
Access: 2006-03-08 13:48:55.000000000 -0500
Modify: 2006-03-04 14:33:37.000000000 -0500
Change: 2006-03-04 14:33:37.000000000 -0500