Knowing the difference between mtime, ctime and atime

If you are dealing with files, you might wonder what the difference is between mtime, ctime and atime.

mtime, or modification time, is when the file was last modified. When you change the contents of a file, its mtime changes.

ctime, or change time, is when the file's property changes. It will always be changed when the mtime changes, but also when you change the file's permissions, name or location.

atime, or access time, is updated when the file's contents are read by an application or a command such as grep or cat.

The easiest way to remember which is which is to read their alphabetical order:

  • Atime can be updated alone
  • Ctime will update atime
  • Mtime will update both atime and ctime.