Linux Commands

Question 1

ls

Answer 1

list directory contents

Question 2

mv

Answer 2

move and rename files

Question 3

rm

Answer 3

remove files and directories

Question 4

more or less

Answer 4

examines files ex. less file name

Question 5

vi

Answer 5

a text editor

Question 6

sudo

Answer 6

super user do, lets you become root user

Question 7

man

Answer 7

manual

Question 8

du

Answer 8

Disk Utilization: du
You will often need to determine where and by whom disk space is being consumed, especially when
you’re running low on it! The du command allows you to determine the disk utilization on a directoryby-
directory basis.

Question 9

cp

Answer 9

copy

Question 10

cat

Answer 10

Concatenate Files: cat
The cat program fills an extremely simple role: it displays files. More creative things can be done
with it, but nearly all of its usage will be in the form of simply displaying the contents of text files—
much like the type command under DOS. Because multiple filenames can be specified on the
command line, it’s possible to concatenate files into a single, large, continuous file. This is different
from tar in that the resulting file has no control information to show the boundaries of different files.

Question 11

pwd

Answer 11

Show Present Working Directory: pwd
Inevitably, you will find yourself at the terminal or shell prompt of an already logged-in workstation
and you won’t know where you are in the file system hierarchy or directory tree. To get this
information, you need the pwd command. Its only task is to print

Question 12

mkdir

Answer 12

create or make a directory

Question 13

passwd

Answer 13

password

Question 14

chown

Answer 14

Change Ownership: chown
The chown command allows you to change the ownership of a file to another user. Only the root user
can do this.

Question 15

chgrp

Answer 15

Change Group: chgrp

The chgrp command-line utility lets you change the group settings of a file. It works much like chown.

Question 16

chmod

Answer 16

Change Mode: chmod (change a files mode)
Directories and files within the Linux file system have permissions associated with them. By default,
permissions are set for the owner of the file, the group associated with the file, and everyone else
who can access the file (also known as owner, group, and other, respectively).
When you list files or directories, you see the permissions in the first column of the output.
Permissions are divided into four parts. The first part is represented by the first character of the
permission. Normal files have no special value and are represented with a hyphen (-) character. If the
file has a special attribute, it is represented by a letter. The two special attributes we are most
interested in here are directories (d) and symbolic links (l).
The second, third, and fourth parts of a permission are represented in three-character chunks. The
first part indicates the file owner’s permission. The second part indicates the group permission. The
last part indicates the world permission. In the context of UNIX, “world” means all users in the
system, regardless of their group settings.

Question 17

ftp

Answer 17

File Transfer Protocol

Question 18

rpm

Answer 18

Use the rpm command to list all the packages that are currently installed on your system.

Question 19

ln

Answer 19

Link Files: ln

The ln command lets you establish hard links and soft links

Question 20

find

Answer 20

Find a File: find
The find command lets you search for files using various search criteria. Like the tools we have
already discussed, find has a large number of options that you can read about in its man page. Here
is the general format of find:

Question 21

chkconfig

Answer 21

check configuration

Question 22

grep

Answer 22

grep is a powerful program used to find text patterns within files.

Question 23

umask

Answer 23

Set the default file permissions…In computing, umask is a command that determines the settings of a mask that controls how file permissions are set for newly created files.

Question 24

ps

Answer 24

Report a snapshot of current processes

List Processes: ps
The ps command lists all the processes in a system, their state, size, name, owner, CPU time, wall
clock time, and much more

Question 25

top

Answer 25

Display Tasks

Show an Interactive List of Processes: top
The top command is an interactive version of ps. Instead of giving a static view of what is going on,
top refreshes the screen with a list of processes every 2–3 seconds (user-adjustable). From this list,
you can reprioritize processes or kill them. Figure 5-1 shows a top screen.

Question 26

jobs

Answer 26

list active jobs

Question 27

bg

Answer 27

Background mount. Should the mount initially fail (for instance, if the server is down), the
mount process will send itself to background processing and continue trying to execute
until it is successful. This is useful for file systems mounted at boot time, because it keeps
the system from hanging at the mount command if the server is down.

Question 28

fg

Answer 28

To bring a job back to the foreground—that is, to give it back control of the terminal—you would
use the fg (foreground)

Question 29

kill

Answer 29

Send a Signal to a Process: kill
This program’s name is misleading: It doesn’t really kill processes. What it does is send signals to
running processes. The operating system, by default, supplies each process with a standard set of
signal handlers to deal with incoming signals.