Lecture notes

• Processes
  • "Processes" refer to running programs.
  • If you run a process, you might want your command prompt back before the process finishes. To do this, type Ctrl-Z. This pauses the process.
  • To let the process resume in the background, use the 'bg' command. To let it resume in the foreground, use 'fg'.
  • If you know on the outset that you want the program to start in the background, when you first call the command, append '&' to it. For example, "grep -r / jerjou &"
  • To see a list of the processes currently running, use the 'ps' command. The 'ps' command has useful options, like '-u'. See the man page for details.
  • If you know the pid (= process id) of a process, you can kill it with the command 'kill'. Other useful commands include 'killall' and 'pkill'. They also have useful flags, one of which is '-KILL' :)
• Telnet & Protocols
  • I do this 'cuz I found it interesting when I first learned it.
  • I went through some examples of how you can test a web and mail server by telnet'ing into the port of the machine the server's running on.
  • Even if you don't know the protocol for the server you're connecting to, telnet'ing to the appropriate port will at least let you know that there's a service running there.