Is ctime always <= mtime?

Question

When using os.stat() in Python, can I assume that st_ctime is always less then or equal to st_mtime? If not, why not?

The code will always run on Linux, but if there is

Answer 1

As @ketil says, ctime is updated when file metadata is changed.

One way this can change is that if you move a file from one directory to another. ctime will change, but not mtime.

touch test_file
mv test_file another_directory/
stat another_directory/test_file 

gives

  File: `another_directory/test_file'
  Size: 0           Blocks: 0          IO Block: 4096   regular empty file
Device: 80ah/2058d  Inode: 23183108    Links: 1
Access: (0644/-rw-r--r--)  Uid: ( 1004/  agrimm)   Gid: ( 1004/  agrimm)
Access: 2011-07-07 10:11:27.000000000 +1000
Modify: 2011-07-07 10:11:27.000000000 +1000
Change: 2011-07-07 10:11:43.000000000 +1000