Understanding Permissions: Notes: List of Terminal Commands

ls -l -pulls up ‘long-listing’ of info

–Once we pull up the ‘long-listing’ of info, the first column gives us specific info on the directory or file. It tells us what you are, or are not allowed to do with that directory or file. (i.e.–permissions).

• Ex. sample permission string: d rwx rwx rwx
  • The ‘d‘ tell us it’s a directory.
  • A hyphen (–) would denote a file.
  • “User“–The first set of ‘rwx‘ refers to the “User“, or the person that “owns” that resource (as listed in Column 3 of the ‘long listing’).
  • “Group“–The second set of ‘rwx‘ refers to the “Group” and designates what the “group” is able to do. (The “group” is listed in Column 4 of the ‘long listing’ info.)
  • “Other“–refers to “everybody else”. i.e.–Everybody who is NOT the ‘user’ (owner) and who is NOT a part of the “group”. Referred to as “Other”, or aka the rest of the world, i.e.–the general public; everybody on the planet; what are they able to do?; what permissions do they have?
  • Key:
    • r—read
    • w—write
    • x–execute
  • Key notes: Ex key: r–read
    • If “r” is designated, it means that person can read that file or read (i.e.–examine) the contents of that directory. If “r” is NOT designated, then that space will be occupied by a hyphen, or dash.
    • Note: This goes on so forth with the rest of the permission string. It will either be that designated character or a hyphen! (Meaning “r”‘s won’t be where “w”‘s go and vice-versa.)
    • *Note: So obviously we want to take care and make sure a Section like Section4–“Other”, aka “the rest of the world”–, doesn’t have the full permission of “rwx”, or they will basically have full access!!!

uptime –tells us how long the system has been “up”, and gives us the load average. For example, you can use this to see if a server has been rebooted recently.

Load average tells us how busy the system is.