If you have been allocated a virtual machine by the instructor, you will log in as SSH. If this is a machine running inside VirtualBox on your laptop, you will probably log in directly on the console.
username: sysadm password: <given in class>
At the command prompt type the following command:
$ sudo -s
Enter the class user's password when prompted
Now that you are root the command prompt will change. We indicate this using the “#” symbol.
You are now the superuser - be careful!
Ok, exit the root account:
# exit $
$ cat /etc/network/interfaces
The IP configuration of your host is either done using DHCP, or configured statically. Which is it in your case ?
“cat” is for “concatenate” and is one way to view what is in a file.
ls to list files:
$ cd [go to your home directory] $ ls
Do you see anything? Try this instead:
$ ls -lah
What's inside one of these files?
$ cat .profile $ less .profile
q to get out of the less display.
If you don't understand what cat, clear or less do, then type:
$ man cat $ man clear $ man less
You can recall previous commands by using the up-arrow and down-arrow keys. Give this a try now.
Alternately, try typing this command:
If you wish to execute one of the commands in the list you saw type:
nn is the number of the command in the history list. This
is useful if you want to run a past command that was long and/or
With the bash shell you can auto-complete commands using the tab key. This means, if you type part of a command, once you have a unique string if you press the TAB key the command will complete. If you press the TAB key twice you'll see all your available options. Your instructor will demonstrate this, but give it a try by doing:
$ hist<TAB> $ del<TAB><TAB> $ rm <TAB><TAB> [Include the space after the "rm"]
We saw an example of using pipes when we sorted the contents of our /sbin directory during the presentation. What if you wanted to have this information available in a file and sorted?
$ cd $ ls /sbin | sort > sbin.txt
Now view the contents of what is in sbin.txt to verify that this worked.
$ less sbin.txt
Press the “q” key to quit viewing the contents.
Use the command grep to print lines matching a pattern in a data stream (such as a file). For example, view the entry for the nsrc account in the system passwd file:
$ sudo grep sysadm /etc/passwd
You should see something like:
The previous items above are:
grep is often used with a pipe to FILTER the output of commands. For instance:
$ history | grep ls
Will display your previous use of the ls command from exercise 2.
It is particularly useful to realize that you can edit a command just as you would a line of text in a file. For instance, you can:
NOTE: you do not need to go to the end of a command before pressing
<ENTER> to execute the command.
Alternatively you can use the reverse-search feature of bash:
Let's give some of these editing rules a try:
$ ls -lah /usr/lib/ | grep postfix
Then, let's look for postfix:
You should now have:
$ ls -lah /usr/sbin/ | grep postfix
With your cursor just past the / in /sbin/, press <ENTER> to execute the command.