Any file present or created in Unix has 3 different time stamps associated with it . The 3 different timings are:
1. Last modified time - This refers to the timing when the file has been modified last. For a newly created file, this refers to the time when the file is created.
2. Last accessed time - This refers to the timing when the file has been accessed last. Access can be either when the file is read, or the file is written to or even if the file has been executed. The last accessed time gets updated when any of the above file operations is being done on a file.
3. Last changed time - This refers to the timing when the file status has been changed last. The change in file status could be due to any of the following reasons:
i) File ownership being changed.
ii) Group to which the file belongs to is changed.
iii) File permissions such as read, write or execute permissions has been applied or removed from the file.
iv) Advanced file permissions such as SUID, SGID or Sticky bit has been applied or removed on the file.
v) When the file content is updated.