First, /dev/null is a special file, not a directory. It's primary purpose is to handle redirection of stdout and stderr. When logs are redirected to the folder, they no longer exist.

Some reference material, Here

With regards to the files in your home directory, it may better to switch from the direct command: /usr/bin/touch -c -t 197501010000 /dev/null

To

/usr/local/bin/mynewscript.sh

Though use your own new file name. So with your favorite editor create the new file, add contents such as: (Change the names accordingly)

#!/bin/bash /usr/bin/touch -m -t 197501010000 /home/username/.bzr.log /usr/bin/touch -m -t 197501010000 /home/username/.xsessions-errors.old /usr/bin/touch -m -t 197501010000 /home/username/.php_history /usr/bin/touch -m -t 197501010000 /home/username/.recently-used

Set execute, on your file:

chmod 455 /usr/local/mynewscript.sh

Next change your service file: /etc/systemd/system/devnull1975.service

[Unit] Description=Changes modified times on log file locate /home/username/ After=graphical-session.target [Service] ExecStart=/bin/sh /usr/local/bin/mynewscript.sh Type=oneshot [Install] WantedBy=multi-user.target Alias=file-touch.service

Use the following to verify no errors are found with the .service file

systemd-analyze verify /etc/systemd/system/devnull1975.service

Refer to this link for more information on systemd.