how exec a command (ex. a cut or grep ) in anoter pc

i have IP address, login and password. (another account of unix system)

what's the sintax of command ???

es. my ip is 192.xx.xx.xx i make a exec of "ls" redirect in outpu file (> "file) in another pc ( ip 192.44.55.2xxx)

Given an IP address, username, and password, you can use ssh to login to other machines, i.e. It will ask you for the password every time.

What if you wanted to access your a computer over the internet, but it was on a lan too (it's ip is spit up by a router).... username@ip_address wouldn't work would it?

'ssh username@ipaddress' should still work, if you're actually ON that lan branch. If it's across the internet behind a NAT firewall, it won't, not unless you arrange for that router to forward port 23 to your computer.