I will add useful Linux and Plesk commands to this list, and expand it as i need these commands.
It will serve mainly as a reminder list to me to look up commands when i need it while working with a Plesk Linux server, but you’re welcome to bookmark and use the list as you see fit.

Plesk:

Recreate plesk php extension list:
plesk bin php_handler –reread

Plesk apache2 logs:
/var/log/apache2/error.log
/var/log/apache2/access.log
/var/www/vhosts/<url>/logs

Linux:

List processes:
ps aux

List processes and filtering them:
ps aux | grep ‘<name>’

Show what the process is currently doing:
strace -p <pid>

List all open files of a process:
lsof -p <pid>

List all open files of a process with ls:
ls -l /proc/<pid>/fd

Delete files or empty directories
rm <filename> //also * placeholders work:

Delete files and non empty directories:
rm -r <file_or_dir_name>

Show file content:
cat <filename>

Create an empty file:
touch <filename>

Link a file or directory to a second place:
ln -s <oldfile> <newfile>

List a directory with extended info:
ls -l <foldername>