Vocabulary
- Authlog = a log containing the things each user did that needed authentication.
- Bash = standard Linux shell
- Basic input-output systems (BIOS): After the POST, the BIOS runs checks on important systems such as the video card and hard drive. Physically, the BIOS is in a ROM chip on the motherboard.
- Bootstrap loader: The first piece of code the computer reads in the hard drive. It is what "boots up" the computer, or "loads the operating system into memory."
- Command line structure
- Prompt: the little flashing block that means, "Yes, may I help you?"
- Command: telling the computer what to do!
- Options: more instructions, usually proceeded by "-" (such as -name when detailing the name of a file)
- Arguments: to whom the action is done
- Configuration: the process of shaping the computer system, such as “telling it” about various drives, video and sound cards, and even user preferences, such as command and display defaults.
- Daemon: Processes that wait in the background, waiting to be told to do something (?? will get more on this later)
- Directory: a list of the files and other directories on the disk(s)
- Free: Some open source software isn't free of charge, but it is free in the sense that one can alter the code and redistribute it.
- Graphical User Interface: This is what most users are used to seeing now. Graphics such as icons and cursors replace the old c:QUIT commands us old people used to have to do when we wanted to take out the ol' 8 inch floppies! Yay for GUIs.
- i-node: metadata on each file that identifies that file with a unique number and address and tells its permissions and type of file.
- Kernel: the core or nucleus of the OS that runs the essential processes: it handles interrupters (when programs "compete" for CPU time) by prioritizing and scheduling when processes can use the memory and it allocates memory and hard disc space. Think of it as the "colonel," and when it says jump we all say how high.
- Modal: in this case (a modal text editor), this means the text editor has two modes to it: command and insert. The user presses certain keys to use insert mode (depending on what s/he wants to do) and presses ESC to return to command mode.
- Permissions: three types-- who can read, write to, and execute a file
- Power-on self test (POST): when a user turns on a computer, the computer does a self-check to make sure that the CPU, memory, and BIOS are running OK. It stores the results and begins powering up.
- Scripts: run when Linux boots system up and down, stops the daemon process
- Shadow file: where passwords (encrypted) are stored
- Shell: the outer part of the OS that "listens" to us, the users. The shell accepts our commands (or doesn't, as the case may be!) and relays them back to the necessary components.
- Ubuntu: an operating system based on Linux. It includes several applications, including a web browser & Open Office. Ubuntu is supported by a community of individuals who use forum space to help others.
- Vim: a “modal” text editor used to configure files. Vim derives its name from Vi Improved, as it is a clone of the text editor vi.
- Windows Registry: the method by which Windows OS is configured. Prior, Windows used .ini files; now the configuration files are located in separate registry “keys” (like folders)
Commands
- bg = put a process in the background
- cat filename = reads from a file and writes whatever it finds from a screen (a catalog?)
- clear = clears the screen
- cd = takes you to home directory
- cd directoryname = changes to the directory named
- chgrp newname oldname: changes a file's group (must be Super User)
- chmod = changes the default permissions
- chmod 123 = using octal digits, changes the default permissions
- chmod o+r myfile = allows "others" to "read" "myfile" (o= owner, g=group)
- chown nameofnewowner nameoffile = changes the file's owner
- cp = copy file or directory
- df -s= lists the amount of free space in all the disks ("disk free")
- du -s= lists the size of the files in the current directory, including the total and how much disk space is used ("disk usage")
- exit = log out of Super User and back to regular log-in.
- fg = put a process in the foreground
- file * = displays the files with an explanation of their types (the * is a wildcard symbol)
- find characteristic -what you want computer to do when it finds file = finds a file and executes a command on it (e.g. find -myfile -print
- grep textString * = searches for a string of text in the current directory
- groupadd = creates a new group. Often used when adding a new user, as each new user is a member of his/her own group. See adding users.
- jobs = lists own processes
- kill = sends a message to a process, usually to KILL IT!!
- less NameofFile = if the file is text, it displays the text ("q" to quit)
- ln DirectoryName LinkName = creates a link; both files are "real," meaning one is not a mere symbol of the other
- ln -s DirectoryName LinkName = creates a symbolic link
- ls = lists the files and directories in the current directory (the directory that is displayed on the last line in use)
- if the output is a terminal, the list is in multiple columns to get more on the screen at once
- ls | more = lists directory contents in one long list with the "more" indicator at the bottom
- Hit enter to scroll down one at a time
- Hit spacebar to scroll down one page at a time
- ls -l = to view the permission settings for files
- mkdir NameofNewDirecory = make a directory
- more filename = lists file contents in one long list with the "more" indicator at the bottom. Or, use more with a pipe.
- more /usr/share/magic = lists the locations and values of "magic" numbers that are inside the files that tell the computer what kind of a file it is
- mv FileName = move file or directory
- netstat -r (or netstat -rn) = view the kernel's routing table (-rn will list numerically)
- ps = lists processes running on the system
- passwd = creates a new password, as in $ sudo passwd kingtut. See adding users.
- pwd = print working directory
- rm file name = removes the file or directory
- rm -r DirectoryName = removes the directory (r = "recursive")
- su = to log in as the Super User (will need to out in password)
- touch nameoffile = create a new, empty file (or modify the time stamp on an existing one) in the current directory
- umask = show the default permissions
- umask 123 = changes default permissions (e.g. 220 means new files have the permission -r--r--rw-); each place is an octal digit
- useradd = adds a new user to the system.
- See Adding Users for more info
Punctuation
Wildcards
* = matches any characters
? = matches any single character
[characters] = matches the set of characters in the brackets, for example [a-j]
[!characters] = matches the set of characters NOT in the brackets, for example [!g]
Other
| = pipes one command through another, connecting one command's output into another's input
\ = tells shell that, yes, the computer needs to read the subsequent symbol (such as \* or \) )
>
= redirecting the output of the command from the default; for example,
ls_>_file_list.txt lists the files in a file called
file_list.txt instead of displaying on the screen as usual
>> = instead of overwriting whatever you redirected above, the file is appended
<
= redirecting the input of the command file from the default; for
example, sort_<_file_list.txt will sort the contents of
file_list.txt
