How to solve: lsof: command not found

The lsof command is available only to root. Anyway, if you want to run it as a normal user, you can specify its full path:

$ /usr/sbin/lsof /path/to/some/file

Or

$ sudo -i lsof /path/to/some/file

Or else:

sudo dnf install lsof

Or

sudo yum install lsof