In this course we will use
the Linux operating system. You will have access to Linux computers at
Chalmers. Another alternative is to install Linux on a part of your computer, keeping
your previous operating system intact. Further
instructions will be available here.
If you just want to
practice Linux without installing it, you find a web-based terminal emulator
here: http://bellard.org/jslinux/.
Some of the commands below do however not work there.
In Linux you have the
option to work graphically or text based. In this course we will work text
based, since that way we have better control of what we are doing (and I am
used to working that way).
To start with, you need to
open a terminal window. You do that either by right-clicking on the desktop and
clicking on 'Terminal' or 'Console', or you should be able to find a button looking
like a computer monitor to click on somewhere. You may also use CTRL-ALT-t.
Once you have a terminal window open you need to know some useful Linux
commands.
Here are some useful Linux
commands. If you do all the commands in the same order as they are presented
below you will go through a small tutorial on how to use these commands:
cd (or: cd ~) |
Move to your home
directory. You should be there already if you just opened the terminal. |
ls |
List the files and directories
in a directory (use this command at any time during the tutorial to see what
files and directories you have in the current directory!) |
ls -l |
List the files in a
directory with extended information |
ls -a |
List all files, including
hidden files (files with names starting with a dot, for example .bashrc) |
mkdir linuxTutorial |
Make a directory named
linuxTutorial. Note that Linux is case-sensitive, i.e. 'linuxTutorials' is
different from 'linuxtutorials'. |
cd linuxTutorial |
Move into the directory
named linuxTutorial |
echo "Hello World!" |
Print "Hello
World" in the terminal window |
echo "A first text
line in my file" > myFile.txt |
Create a file named
myFile.txt, and add a line to it saying: "A first text line in my file".
The '>' re-directs the output from the echo command to a file instead of
to the terminal window. |
echo "A second text
line in my file" >> myFile.txt |
Append the line "A
second text line in my file" to myFile.txt. The '>>' appends the output
of the echo command to the same file as before. If we had used the '>' we
would have overwritten the file instead. |
cp myFile.txt
copyOfMyFime.txt |
Copy the file (check with
ls!) |
rm myFile.txt |
remove the original file
(check with ls!) |
mv copyOfMyFime.txt
myFile.txt |
Rename the new file to
the name of the original file (check with ls!) |
mkdir aSecondDirectory |
Make a directory named
aSecondDirectory inside the linuxTutorial directory (check with ls!) |
cd aSecondDirectory |
Move inside aSecondDirectory |
cd .. |
Move up one directory, in
this case to the directory named linuxTutorial |
rmdir aSecondDirectory |
Remove the empty
directory named aSecondDirectory |
mkdir -p
aSecondDirectory/aThirdDirectory/aFourthDirectory |
Create this directory
structure inside the linuxTutorial directory |
cp myFile.txt
aSecondDirectory/aThirdDirectory/aFourthDirectory |
Copy the file to the
directory named aFourthDirectory |
ls aSecondDirectory/aThirdDirectory/aFourthDirectory |
List the files in the
directory named aFourthDirectory |
cd aSecondDirectory/aThirdDirectory/aFourthDirectory |
Go to the directory named
aFourthDirectory |
pwd |
Show your current
directory path |
cd ../../.. |
Move up three directory levels
(you should now be in the linuxTutorial directory (check with pwd) |
tree -L 3 |
Print out directory
structure in the terminal window |
tree -L 2 |
Print out only two levels
of the directory structure |
tree -d |
Print out only the directories
in the directory structure |
more myFile.txt |
View the contents of
myFile.txt. If the file is large you exit with 'q', and move down in the file
by pressing 'Enter' |
head myFile.txt |
View the beginning
myFile.txt (in this case it shows all of the file since it is small). |
tail myFile.txt |
View the end of
myFile.txt (in this case it shows all of the file since it is small). |
tail -f myFile.txt |
View the end of a file and update when lines are added to the file. Exit with 'CTRL-c' |
tailf myFile.txt |
Same as 'tail -f', but can be faster. Exit with 'CTRL-c' |
grep "second text
line" myFile.txt |
Search for the string
"second text line" in myFile.txt, and print out all lines that
match |
grep -r "first text
line" aSecondDirectory |
Search for the string
"first text line" recursively in the directory named
aSecondDirectory |
find aSecondDirectory -iname "*yfi*" |
Find all files that have
the string 'yfi' in their file name. The string is not case sensitive because
we use the flag -iname. The '*' means 'any string'. The command is recursive.
|
sed -i s/"second
text line"/"modified text line"/g myFile.txt |
Substitute the string
"second text line" in myFile.txt with "modified text". Use
your Linux skills to check that it was done! The sed-commands can also be
used in the 'vi' editor which will be discussed later. |
mkdir newDirectory cp --parents
aSecondDirectory/aThirdDirectory/aFourthDirectory/myFile.txt newDirectory |
Make a new directory and
copy the whole file structure of myFile.txt into that directory. Use your
Linux knowledge to check out the directory structure, and then remove
newDirectory. |
rm -r aSecondDirectory |
remove directory
aSecondDirectory and all files and directories in it (rmdir does not work if
there are files or directories in a directory) |
ln -s myFile.txt
softLinkToMyFile.txt |
Make a soft link to
myFile.txt. The original file will NOT be copied, but the name softLinkToMyFile.txt
will point at myFile.txt. If you edit softLinkToMyFile.txt tou will actually
edit myFile.txt. However, removing softLinkToMyFile.txt will only remove the
link, and not myFile.txt. You can see links using the 'ls -l' command,
showing the sign '->', meaning that it points at another file. |
touch touchedFile.txt |
Create a file without
opening it, and without adding anything in it. |
cd ; rm -r linuxTutorial |
Removes the linuxTutorial
directory. Note that we here do two commands at the same line, first a cd,
and then an rm! |
exit |
close connection (terminal window) |
Here are some useful Linux
commands. If you do all the commands in the same order as they are presented
below you will go through a small tutorial on how to use these commands:
xlogo & |
Put a job in background
when starting it. 'xlogo' is the job we run in this case, and '&' puts it
in background, so that you can continue working in the terminal window. Of
course, any other process than xlogo can be used. |
jobs |
List background jobs in
the current terminal window. |
ps -ef | grep xlogo |
List all the processes on
the computer containing the string 'xlogo'. The 'ps -ef' command lists all
the processes on the computer. The '|' sign sends that output to the 'grep
xlogo' command, which makes sure that only lines containing the string
'xlogo' are shown. The first number on each line is the process id (PID). |
fg |
Put a process in
foreground, in this case the xlogo process |
CTRL-c |
Kill a process in
foreground, in this case the xlogo process |
xlogo CTRL-z |
Start a job in foreground
(i.e., don't use the '&' sign), which will lock the terminal window from
further work. The process can be stopped using CTRL-z, but the process will
be paused until it is put in background with the 'bg' command. |
top |
Show the activity of all the processes on the computer. The first number on each line is the process id (PID). Exit by typing 'q'. |
kill <PID> |
Kill a job in background.
Find the process id (PID) from the ps command, or the top command. |
Kill -9 <PID> |
If the 'kill' command doesn't
work, try to add the -9 flag, which should force the kill. |
which xlogo |
Prints the full path to
the xlogo executable, so that you can check that you are running the file you
think that you are running. |
Find other useful Linux commands
by doing the following:
info coreutils
info coreutils ls
info coreutils nohup
(exit by typing 'q')
Once you know the name of a command, learn how to use it by:
man command
(exit by typing 'q')
For editing files
interactively you use a text editor. I commonly use 'vi', which is a VERY
simple text editor. The benefits of vi is that it is quick to open files, and
it does not open any new window. You do the editing directly in the terminal
window. Several of the vi commands can also be used in the man pages and in sed
commands. On the downside, there is no graphical user interface. Search the
internet for short introductions to vi, for example: http://www.cs.colostate.edu/helpdocs/vi.html
Other alternaties are:
emacs
gedit
nedit
If you are interested in
why the file system looks as it does, see:
http://www.pathname.com