When I modify the content of a file, for example by date > f.txt then I execute stat f.txt
I see that both last status change time and last modification time are both are changed.
I am looking for two scenarios to see a change in one timestamp without changeing the other
These are two very different kinds of timestamp :
Modify is the timestamp of the last time the file's content
has been modified, often called mtime.
Change is the timestamp of the last time the file's inode has been changed, like by changing metadata such as permissions, ownership, file name, number of hard links. It's often called ctime.
Modification time can be change by using the
touch command
with the -m parameter.
For examples of using touch, see the post
How can I change the date modified/created of a file?
As regarding the last status change time, see the post How can I change 'change' date of file? where the answer by user "Gilles SO - stop being evil" says:
You cannot change the ctime by ordinary means. This is by design: the ctime is always updated to the current when you change any of the file's metadata, and there is no way to impose a different ctime. To change the ctime of a file, you need to do one of the following:
- Set the system time to the ctime you want to impose, then touch the file, then reset the system time.
- Modify the kernel to add an interface to change the ctime.
- Access the disk image directly (e.g. with
debugfs) and twiddle the bits on the disk (don't do it while the filesystem is mounted).
The answer by user Coren gave the exact method :
You have the answer on related SO question pointed by jw013, for extX, on unmounted disk :
# Update ctime debugfs -w -R 'set_inode_field /tmp/foo ctime 201001010101' /dev/sda1 # Drop vm cache so ctime update is reflected echo 2 > /proc/sys/vm/drop_caches
