How can I change 'change' date of file?

Question

How can I change the "change" date of a file? Using touch doesn't work:

$ touch -t 9901010000 test;stat test
  File: `test'
  Size: 0           Blocks: 0          IO Block: 4096   regular empty file
Device: fe01h/65025d    Inode: 11279017    Links: 1
Access: (0644/-rw-r--r--)  Uid: ( 1000/    x)   Gid: ( 1000/    x)
Access: 1999-01-01 00:00:00.000000000 +0100
Modify: 1999-01-01 00:00:00.000000000 +0100
Change: 2012-04-08 19:26:56.061614473 +0200
 Birth: -

Answer 1

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).

Answer 2

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

Answer 3

$ NOW=$(date) && date -s "2030-08-15 21:30:11" && touch file.txt && date -s "$NOW"

https://www.shellhacks.com/fake-file-access-modify-change-timestamps-linux

Answer 4

The ctime of a file is updated when any of the metadata is changed.

$ ls -l x.py
-rw-rw-r--. 1 ignacio ignacio 485 Mar 26  2010 x.py
$ stat -c %z x.py
2010-03-26 11:57:56.237068175 -0400
$ chown ignacio x.py
$ stat -c %z x.py
2012-04-08 15:31:33.682383575 -0400
$ ls -l x.py
-rw-rw-r--. 1 ignacio ignacio 485 Mar 26  2010 x.py

Answer 5

evandrix's answer excerpted in the next line,
NOW=$(date) && date -s "2030-08-15 21:30:11" && touch file.txt && date -s "$NOW"
needs to be improved as described below :

In some systems like mine, date output doesn't give a valid format to set with date -s

My system bash shell version : GNU bash, version 5.0.3(1)-release (x86_64-pc-linux-gnu)
My system date command version : date (GNU coreutils) 8.30

My system date command output and setting the date with this format is:

# date
Tue 21 Jan 2020 01:36:22 PM +03
# date -s "Tue 21 Jan 2020 01:36:22 PM +03"
date: invalid date ‘Tue 21 Jan 2020 01:36:22 PM +03’

So it is necessary to improve evandrix answer;
It would be better to assign the NOW variable to the timestamp value
change NOW=$(date) to NOW=$(date +@%s)

  NOW=$(date +@%s) && date -s "2030-08-15 21:30:11" && \
  touch file.txt && date -s "$NOW"

Adding sudo command for non root user

  sudo bash -c 'NOW=$(date +@%s);
                date -s "2030-08-15 21:30:11";
                touch file.txt;
                date -s "$NOW"'

or

  sudo bash -c 'NOW=$(date +@%s); date -s "$2"; touch "$1"; date -s "$NOW"' -- \
                "file.txt" "2030-08-15 21:30:11"

In this way for easy use, the filename and setting date are assigned as arguments at the end of the line.

Answer 6

I use ln for this case. The meta data is changed to increase and decrease the reference counter.

# $file contains the filename
ln "$file" "$file.xxx.tmp"
rm -f "$file.xxx.tmp"

Here I use .xxx.tmp as extension for the temporary file and hope, that it will not used by any other.