Unix Primer

Revised by Vince Filby <vfilby@acm.org>
Written by John Isam <blackstaff@eddie.cis.uoguelph.ca>

Introduction

This document will provide some of the basic commands of Unix. I
suggest you print this if you are a first time Unix user, or are about
to install Unix for the first time. It is always good to have a
reference, so that when you see your first prompt, you have an idea of
how to move around.

The Beginning

To give commands to Unix, you must type them after the Unix shell
prompt. On most Unix machines, the prompt is usually the character '%', or
'#' for root (ignore the '' marks).

Usually the '%' prompt is preceded by a string of characters that
represent the part of the Unix file system that is the current
directory. The current directroy is displayed automatically for you as a
way to help you remember where in the file systems you are.

In general Unix pays attention to the case of what you type. The
commands 'ls' and 'LS' are not the same. If you think you are typing
good commands, but Unix doesn't like them, check that you haven't set
Caps Lock on your keyboard.

The following are some of the basic commands, that Unix uses. There are
many other commands available that I won't cover.

Basic Unix Commands

man <command>

Displays the section of the Unix manual concerning <command>. For example, 'man ls' displays information about the 'ls' command. 'man man' shows information about the 'man' command. This is linux's version of online help. This is also a good way to learn about all the tags that certain commands have. For example 'ls -a' provides a different output, then just 'ls' would.

ls

Lists the files in the current directory.

ls <pathname>

Lists files in the directory described by <pathname>.

<tab> completion

This isn't really a command, but you will soon find it to be very useful. Unix supports long, VERY LONG file names. To save time typing, just type the first letter or two of a directory, or file, then hit the button. Linux will complete the typing for you. If there are other files too similar to what you've typed so far, you might have to type a few more letters, before will finish the file/directory for you. *note* that this is dependant on what shell you are using and isn't always available.

mv <pathname1> <pathname2>

Moves the file found at <pathname1> to the position specified by <pathname2>. After you move a file, it no longer exists at <pathname1>

cp <pathname1> <pathname2>

Copies the file at <pathname1> to <pathname2>. Works like the 'mv' command, except the file found <pathname1> is not destroyed when written to <pathname2>. If there was a file at <pathname2> it is destroyed/overwritten.

rm <pathname1>

Removes <destroys/deletes> the file at <pathname1>

mkdir <pathname1>

Makes a directory with the name specified by <pathname1>.

cd <pathname1>

Changes the current directory to be that specified by <pathname1>

pwd

Displays what the current directory is. Stands for print working directory.

rmdir <pathname1>

Removes the directory specified by <pathname1>

cat <pathname1>

Allows you to view the contents of a file. This works best for files that contain simple characters, instead of executable programs.

cat <pathname1> <pathname2>

Adds the file at <pathname2> to the end of the file at <pathname1>. This is called concatenation. The result is a single file with the name <pathname1>, having the contents of both.

telnet <address>

Allows you to connect to the computer at <address>. However the computer must be willing to accept users, and you must have an account on that computer.

rlogin <address>

Similar to telnet. Stands for remote login.

ftp <address>

Allows you to connect to the computer at <address>. Much like telnet, only the purpose of ftp is to send/receive files from/to <address>. Stands for file transfer protocal.

ncftp <address>

Similar to ftp, only slightly more graphical, easier to use.

talk <user>

Used to chat with another user on the same machine.

w

Used to see all present users, and what they are doing.

su <user>

Used to switch user. Often used to telnet into a machine, and switch to root. Stands for substitute user identity.

mount

Used to mount file systems. Usually restricted to root only. Enables Unix to read from floppy drives, cdrom, and non linux partitions. Can be complicated, but here is an example of a mount command, to mount your cdrom. eg - 'mount /dev/cdrom /mnt/cdrom' Then to read your cdrom, you would look in the directory '/mnt/cdrom'.

umount

Used to unmount, mounted file systems. This is usually required with floppies, in order to ensure all files are saved/updated. An example of unmounting the mount done in the previous example is: 'umount /mnt/cdrom'. This will also enable you to open your cdrom, as it can't be opened, when mounted.

logout

Used to logout of login shells.

exit

Used to exit non-login shells.

shutdown <tag> <time>

Used to shutdown the system at a given time. Usually only root has this command. Can be used to reboot the system, to shutdown and halt the system, and also allows you to provide a warning message to any users on the system. eg use: 'shutdown -r now' will reboot the system, immediately.

reboot

Very similar to shutdown.

pine

Starts the e-mail mailer pine. This is one of the mailers that is available. It seems to be the standard for U of G.

ctrl-c

Often used to kill off operations. An example is to end a talk session.

mcopy

Part of the mtools utility provided with Unix. Used to move/copy msdos files to/from linux. Often used in the labs, to copy files to/from disks.

pico

Basic editor, similar to edit in dos.

vi

Complex, and powerful text editor.

vim

Similar to vi. Stands for Vi IMproved. It is considered a programmers text editor.

Some X Window Commands

I will not spend much time on these, as X can be complicated, but these
commands will get you started.

startx, xinit, xdm, Xconfigurator, XF86Setup, Xvidtune, X,

Some Files to Look At

Here are a brief list of files you should look at. I don't suggest
changing or altering them, until you know what they do. Many of them are
only created for certain shells, so don't be worried, if you don't have
some of them. I will use '~' to represent your home directory.

~/.xinitrc, /etc/fstab, /etc/inetd.conf, /etc/passwd, ~/.tcshrc,
~/cshrc,

Revision History
1.1 - Converted to HTML and minor changes made
1.0 - Written by John Isam