Recently we wanted to check when did the permissions of a specific file changed.
Unfortunately, there exists no such flag and we do not have a 100% working solution for it.
What we did was to check the last modification time of the file status information (ctime) using the ls -lc command.
This command could indicate the last permissions change time but it is not a reliable source as it represents the modification time of other elements as well.
The modification time of the file status information (ctime) gets updated when any inode information regarding the file changes.
This means that the modification time of the file status information (ctime) will get updated when any of the following changes:
owner– The numeric user ID (UID) of the file’s owner.group– The numeric group ID (GID) of the file’s group.link count– The number of links to the file.mode– The bit string that indicated the permissions and privilegesserial– The serial number of the file.device– The numeric ID of the device containing the file.
Explanation of ls parameters
- The parameter
-cof thelscommand when used with the-lwill showctimeand sort by name. - The parameter
-cof the ls command when used with the-land the-twill showctimeand sort byctime(newest first).
Example that demonstrates that we get different values in the time column of -l when -c is used
$ ls -lc ~/.ssh/ total 28 -rwx------. 1 george george 225 May 16 17:05 config -rwx------. 1 george george 1743 Jun 2 13:36 id_rsa -rwxrwx---. 1 george george 405 May 16 17:05 id_rsa.pub -rwxrwx---. 1 george george 32 May 16 17:05 Details.txt -rw-r--r--. 1 george george 9155 May 30 14:32 known_hosts $ ls -l ~/.ssh/ total 28 -rwx------. 1 george george 225 Mar 22 11:36 config -rwx------. 1 george george 1743 Jan 25 10:22 id_rsa -rwxrwx---. 1 george george 405 Jan 25 10:22 id_rsa.pub -rwxrwx---. 1 george george 32 Jan 25 10:22 Details.txt -rw-r--r--. 1 george george 9155 May 30 14:32 known_hosts
This post is also available in: Greek
