如何使用PHP代码登录到linux服务器?

I want to make a GUI for automation testing tool, currently that was in CLI and we need to convert it ig GUI, now the problem i am facing is that I have selected HTML,CSS,JS for front end and PHP for backend, so can any 1 of u suggest me how to login to the server, which is having some IP? or simply how to login to linux server using PHP code?I want to make a GUI for automation testing too