bug#79488: [RFE] Enhancement idea : Better Handling of File Permission with CHMOD Command

On 22/09/2025 06:55, Mahish Sivan S (Nokia) via GNU coreutils Bug Reports wrote:
> Hello coreutils team,
> 
> I would like to suggest an improvement to the "CHMOD" utility in GNU coreutils.
> 
> Current behaviour:
> -----------------------
> The chmod command allows us to change file permissions. However, in the current implementation, it does not support granting permissions for a specific time period.
> 
> Suggestion for improvement:
> -----------------------------------
> Introduce a new time flag (for example, `-t`) that accepts a duration in minutes. With this option, users could grant permissions to a file for a specific time period instead of permanently. Once the specified time expires, the file's permissions would automatically revert to their default state.
> 
> Example (if possible):
> --------------------------
> $ chmod 777 -t 30 myfile.txt
> # Grants full access to "myfile.txt" for 30 minutes
> # After 30 minutes, permissions revert to their previous state
> 
> Ex :
> 
> Current:
>     $ls -al
>     -r--r--r-- 1 user user 1.1G Sep 18 10:20 file.iso
>     $ chmod 777 file.iso
>     -rwxrwxrwx 1 user user 1.1G Sep 18 10:20 file.iso
> 
> Proposed with `-t`:
>     $ chmod 777 -t 15 file.iso
>     -rwxrwxrwx 1 user user 1.2G Sep 18 10:20 file.iso
> After 15 min
>     -r--r--r-- 1 user user 1.2G Sep 18 10:20 file.iso
> 
> Rationale:
> ------------
> This feature would be useful in scenarios where temporary access needs to be granted, such as:
> - Allowing a colleague or process to access a file for a short duration
> - Enhancing security by automatically revoking access after the required time window
> - Reducing the risk of leaving sensitive files over-exposed due to forgotten manual permission changes
> 
> Environment:
> ----------------
> - OS/Distribution: Ubuntu 22.04
> - Coreutils version: cmod (GNU coreutils) 9.1
> 
> Thank you for maintaining coreutils and considering this suggestion.

I'm not sure this is a good idea (what about reboots).
In any case it would be best achieved with a tool/script
driving the existing functions/utilities rather than
with the utilities themselves.

thanks,
Padraig