Top 100 Linux Interview Questions

Top 100 Linux Interview Questions

1. You attempt to use shadow passwords but are unsuccessful. What characteristic of the
/etc/passwd file may cause this? Choose one: a. The login command is missing. b. The
username is too long. c. The password field is blank. d. The password field is prefaced by
an asterick.
2. You create a new user account by adding the following line to your /etc/passwd file.
bobm:baddog:501:501:Bob Morris:/home/bobm:/bin/bash Bob calls you and tells you that
he cannot logon. You verify that he is using the correct username and password. What is
the problem? Choose one: a. The UID and GID cannot be identical. b. You cannot have
spaces in the line unless they are surrounded with double quotes. c. You cannot directly
enter the password; rather you have to use the passwd command to assign a password
to the user. d. The username is too short, it must be at least six characters long.
3. Which of the following tasks is not necessary when creating a new user by editing the
/etc/passwd file? Choose one: a. Create a link from the user’s home directory to the shell
the user will use. b. Create the user’s home directory c. Use the passwd command to
assign a password to the account. d. Add the user to the specified group.
4. You create a new user by adding the following line to the /etc/passwd file
bobm::501:501:Bob Morris:/home/bobm:/bin/bash You then create the user’s home
directory and use the passwd command to set his password. However, the user calls you
and says that he cannot log on. What is the problem? Choose one: a. The user did not
change his password. b. bobm does not have permission to /home/bobm. c. The user did
not type his username in all caps. d. You cannot leave the password field blank when
creating a new user.
5. When using useradd to create a new user account, which of the following tasks is not
done automatically. Choose one: a. Assign a UID. b. Assign a default shell. c. Create the
user’s home directory. d. Define the user’s home directory.
6. You issue the following command useradd -m bobm But the user cannot logon. What is
the problem? Choose one: a. You need to assign a password to bobm’s account using
the passwd command. b. You need to create bobm’s home directory and set the
appropriate permissions. c. You need to edit the /etc/passwd file and assign a shell for
bobm’s account. d. The username must be at least five characters long.
7. You have created special configuration files that you want copied to each user’s home
directories when creating new user accounts. You copy the files to /etc/skel. Which of the
following commands will make this happen? Choose one: a. useradd -m username b.
useradd -mk username c. useradd -k username d. useradd -Dk username
8. Mary has recently gotten married and wants to change her username from mstone to
mknight. Which of the following commands should you run to accomplish this? Choose
one: a. usermod -l mknight mstone b. usermod -l mstone mknight c. usermod -u mknight
mstone d. usermod -u mstone mknight
9. After bob leaves the company you issue the command userdel bob. Although his entry in
the /etc/passwd file has been deleted, his home directory is still there. What command
could you have used to make sure that his home directory was also deleted? Choose
one: a. userdel -m bob b. userdel -u bob c. userdel -l bob d. userdel -r bob
10. All groups are defined in the /etc/group file. Each entry contains four fields in the following
order. Choose one: a. groupname, password, GID, member list b. GID, groupname,
password, member list c. groupname, GID, password, member list d. GID, member list,
groupname, password
11. You need to create a new group called sales with Bob, Mary and Joe as members. Which
of the following would accomplish this? Choose one: a. Add the following line to the
/etc/group file: sales:44:bob,mary,joe b. Issue the command groupadd sales. c. Issue the
command groupadd -a sales bob,mary,joe d. Add the following line to the /etc/group file:
sales::44:bob,mary,joe
12. What command is used to remove the password assigned to a group?
13. You changed the GID of the sales group by editing the /etc/group file. All of the members
can change to the group without any problem except for Joe. He cannot even login to the
system. What is the problem? Choose one: a. Joe forgot the password for the group. b.
You need to add Joe to the group again. c. Joe had the original GID specified as his
default group in the /etc/passwd file. d. You need to delete Joe’s account and recreate it.
14. You need to delete the group dataproject. Which two of the following tasks should you do
first before deleting the group? A. Check the /etc/passwd file to make sure no one has
this group as his default group. B. Change the members of the dataproject group to
another group besides users. C. Make sure that the members listed in the /etc/group file
are given new login names. D. Verify that no file or directory has this group listed as its
owner. Choose one: a. A and C b. A and D c. B and C d. B and D
15. When you look at the /etc/group file you see the group kmem listed. Since it does not
own any files and no one is using it as a default group, can you delete this group?
16. When looking at the /etc/passwd file, you notice that all the password fields contain ‘x’.
What does this mean? Choose one: a. That the password is encrypted. b. That you are
using shadow passwords. c. That all passwords are blank. d. That all passwords have
expired.
17. In order to improve your system’s security you decide to implement shadow passwords.
What command should you use?
18. What file contains the default environment variables when using the bash shell? Choose
one: a. ~/.profile b. /bash c. /etc/profile d. ~/bash
19. You have created a subdirectory of your home directory containing your scripts. Since
you use the bash shell, what file would you edit to put this directory on your path?
Choose one: a. ~/.profile b. /etc/profile c. /etc/bash d. ~/.bash
20. Which of the following interprets your actions when typing at the command line for the
operating system? Choose One a. Utility b. Application c. Shell d. Command
21. What can you type at a command line to determine which shell you are using?
22. You want to enter a series of commands from the command-line. What would be the
quickest way to do this? Choose One a. Press enter after entering each command and its
arguments b. Put them in a script and execute the script c. Separate each command with
a semi-colon (;) and press enter after the last command d. Separate each command with
a / and press enter after the last command
23. You are entering a long, complex command line and you reach the right side of your
screen before you have finished typing. You want to finish typing the necessary
commands but have the display wrap around to the left. Which of the following key
combinations would achieve this? Choose One a. Esc, /, Enter b. /, Enter c. ctrl-d, enter
d. esc, /, ctrl-d
24. After typing in a new command and pressing enter, you receive an error message
indicating incorrect syntax. This error message originated from.. Choose one a. The shell
b. The operating system c. The command d. The kernel
25. When typing at the command line, the default editor is the _____________ library.
26. You typed the following at the command line ls -al /home/ hadden. What key strokes
would you enter to remove the space between the ‘/’ and ‘hadden’ without having to
retype the entire line? Choose one a. Ctrl-B , Del b. Esc-b , Del c. Esc-Del , Del d. Ctrl-b ,
Del
27. You would like to temporarily change your command line editor to be vi. What command
should you type to change it?
28. After experimenting with vi as your command line editor, you decide that you want to
have vi your default editor every time you log in. What would be the appropriate way to
do this? Choose one a. Change the /etc/inputrc file b. Change the /etc/profile file c.
Change the ~/.inputrc file d. Change the ~/.profile file
29. You have to type your name and title frequently throughout the day and would like to
decrease the number of key strokes you use to type this. Which one of your configuration
files would you edit to bind this information to one of the function keys?
30. In your present working directory, you have the files maryletter memo1
MyTelephoneandAddressBook What is the fewest number of keys you can type to open
the file MyTelephoneandAddressBook with vi? Choose one a. 6 b. 28 c. 25 d. 4
31. A variable that you can name and assign a value to is called a _____________ variable.
32. You have installed a new application but when you type in the command to start it you
get the error message Command not found. What do you need to do to fix this problem?
Choose one a. Add the directory containing the application to your path b. Specify the
directory’s name whenever you run the application c. Verify that the execute permission
has been applied to the command. d. Give everyone read, write and execute permission
to the application’s directory.
33. You telnet into several of your servers simultaneously. During the day, you sometimes
get confused as to which telnet session is connected to which server. Which of the
following commands in your .profile file would make it obvious to which server you are
attached? Choose one a. PS1=’\h: \w>’ b. PS1=’\s: \W>’ c. PS1=’\!: \t>’ d. PS1=’\a: \n>’
34. Which of the following environment variables determines your working directory at the
completion of a successful login? Choose one a. HOME b. BASH_ENV c. PWD d.
BLENDERDIR
35. Every time you attempt to delete a file using the rm utility, the operating system prompts
you for confirmation. You know that this is not the customary behavior for the rm
command. What is wrong? Choose one a. rm has been aliased as rm -i b. The version of
rm installed on your system is incorrect. c. This is the normal behavior of the newest
version of rm. d. There is an incorrect link on your system.
36. You are running out of space in your home directory. While looking for files to delete or
compress you find a large file called .bash_history and delete it. A few days later, it is
back and as large as before. What do you need to do to ensure that its size is smaller?
Choose one a. Set the HISTFILESIZE variable to a smaller number. b. Set the HISTSIZE
to a smaller number. c. Set the NOHISTFILE variable to true. d. Set the HISTAPPEND
variable to true.
37. In order to display the last five commands you have entered using the history command,
you would type ___________.
38. In order to display the last five commands you have entered using the fc command, you
would type ___________.
39. You previously ran the find command to locate a particular file. You want to run that
command again. What would be the quickest way to do this? Choose one a. fc -l find fc n
b. history -l find history n c. Retype the command d. fc -n find
40. Using command substitution, how would you display the value of the present working
directory? Choose one a. echo $(pwd) b. echo pwd c. $pwd d. pwd | echo
41. You need to search the entire directory structure to locate a specific file. How could you
do this and still be able to run other commands while the find command is still searching
for your file? Choose one a. find / -name filename & b. find / -name filename c. bg find /
-name filename d. &find / -name filename &
42. In order to create a file called DirContents containing the contents of the /etc directory
you would type ____________.
43. What would be displayed as the result of issuing the command ps ef? Choose one a. A
listing of the user’s running processes formatted as a tree. b. A listing of the stopped
processes c. A listing of all the running processes formatted as a tree. d. A listing of all
system processes formatted as a tree.
44. What utility can you use to show a dynamic listing of running processes? __________
45. The top utility can be used to change the priority of a running process? Another utility that
can also be used to change priority is ___________?
46. What key combination can you press to suspend a running job and place it in the
background?
47. You issue the command jobs and receive the following output: [1]- Stopped (tty output)
pine [2]+ Stopped (tty output) MyScript How would you bring the MyScript process to the
foreground? Choose one: a. fg %2 b. ctrl-c c. fg MyScript d. ctrl-z
48. You enter the command cat MyFile | sort > DirList & and the operating system displays
[4] 3499 What does this mean? Choose one a. This is job number 4 and the PID of the
sort command is 3499. b. This is job number 4 and the PID of the job is 3499. c. This is
job number 3499 and the PID of the cat command is 4. d. This is job number 4 and the
PID of the cat command is 3499.
49. You attempt to log out but receive an error message that you cannot. When you issue the
jobs command, you see a process that is running in the background. How can you fix this
so that you can logout? Choose one a. Issue the kill command with the PID of each
running command of the pipeline as an argument. b. Issue the kill command with the job
number as an argument. c. Issue the kill command with the PID of the last command as
an argument. d. Issue the kill command without any arguments.
50. You have been given the job of administering a new server. It houses a database used
by the sales people. This information is changed frequently and is not duplicated
anywhere else. What should you do to ensure that this information is not lost? Choose
one a. Create a backup strategy that includes backing up this information at least daily. b.
Prepare a proposal to purchase a backup server c. Recommend that the server be made
part of a cluster. d. Install an additional hard drive in the server.
51. When planning your backup strategy you need to consider how often you will perform a
backup, how much time the backup takes and what media you will use. What other factor
must you consider when planning your backup strategy? _________
52. Many factors are taken into account when planning a backup strategy. The one most
important one is how often does the file ____________.
53. Which one of the following factors does not play a role in choosing the type of backup
media to use? Choose one: a. How frequently a file changes b. How long you need to
retain the backup c. How much data needs to be backed up d. How frequently the backed
up data needs to be accessed
54. When you only back up one partition, this is called a ______ backup. Choose one a.
Differential b. Full c. Partial d. Copy
55. When you back up only the files that have changed since the last backup, this is called a
______ backup. Choose one a. Partial b. Differential c. Full d. Copy
56. The easiest, most basic form of backing up a file is to _____ it to another location.
57. When is the most important time to restore a file from your backup? Choose one a. On a
regular scheduled basis to verify that the data is available. b. When the system crashes.
c. When a user inadvertently loses a file. d. When your boss asks to see how restoring a
file works.
58. As a system administrator, you are instructed to backup all the users’ home directories.
Which of the following commands would accomplish this? Choose one a. tar rf usersbkup
home/* b. tar cf usersbkup home/* c. tar cbf usersbkup home/* d. tar rvf usersbkup
home/*
59. What is wrong with the following command? tar cvfb / /dev/tape 20 Choose one a. You
cannot use the c option with the b option. b. The correct line should be tar -cvfb /
/dev/tape20. c. The arguments are not in the same order as the corresponding modifiers.
d. The files to be backed up have not been specified.
60. You need to view the contents of the tarfile called MyBackup.tar. What command would
you use? __________
61. After creating a backup of the users’ home directories called backup.cpio you are asked
to restore a file called memo.ben. What command should you type?
62. You want to create a compressed backup of the users’ home directories so you issue the
command gzip /home/* backup.gz but it fails. The reason that it failed is that gzip will only
compress one _______ at a time.
63. You want to create a compressed backup of the users’ home directories. What utility
should you use?
64. You routinely compress old log files. You now need to examine a log from two months
ago. In order to view its contents without first having to decompress it, use the
_________ utility.
65. Which two utilities can you use to set up a job to run at a specified time? Choose one: a.
at and crond b. atrun and crontab c. at and crontab d. atd and crond
66. You have written a script called usrs to parse the passwd file and create a list of
usernames. You want to have this run at 5 am tomorrow so you can see the results when
you get to work. Which of the following commands will work? Choose one: a. at 5:00 wed
usrs b. at 5:00 wed -b usrs c. at 5:00 wed -l usrs d. at 5:00 wed -d usrs
67. Several of your users have been scheduling large at jobs to run during peak load times.
How can you prevent anyone from scheduling an at job? Choose one: a. delete the file
/etc/at.deny b. create an empty file called /etc/at.deny c. create two empty files:
/etc/at.deny and /etc/at.allow file d. create an empty file called /etc/at.allow
68. How can you determine who has scheduled at jobs? Choose one: a. at -l b. at -q c. at -d
d. atwho
69. When defining a cronjob, there are five fields used to specify when the job will run. What
are these fields and what is the correct order? Choose one: a. minute, hour, day of week,
day of month, month b. minute, hour, month, day of month, day of week c. minute, hour,
day of month, month, day of week d. hour, minute, day of month, month, day of week
70. You have entered the following cronjob. When will it run? 15 * * * 1,3,5 myscript Choose
one: a. at 15 minutes after every hour on the 1st, 3rd and 5th of each month. b. at 1:15
am , 3:15 am, and 5:15 am every day c. at 3:00 pm on the 1st, 3rd, and 5th of each
month d. at 15 minutes after every hour every Monday, Wednesday, and Friday
71. As the system administrator you need to review Bob’s cronjobs. What command would
you use? Choose one: a. crontab -lu bob b. crontab -u bob c. crontab -l d. cronq -lu bob
72. In order to schedule a cronjob, the first task is to create a text file containing the jobs to
be run along with the time they are to run. Which of the following commands will run the
script MyScript every day at 11:45 pm ? Choose one: a. * 23 45 * * MyScript b. 23 45 * * *
MyScript c. 45 23 * * * MyScript d. * * * 23 45 MyScript
73. Which daemon must be running in order to have any scheduled jobs run as scheduled?
Choose one: a. crond b. atd c. atrun d. crontab
74. You want to ensure that your system is not overloaded with users running multiple
scheduled jobs. A policy has been established that only the system administrators can
create any scheduled jobs. It is your job to implement this policy. How are you going to
do this? Choose one: a. create an empty file called /etc/cron.deny b. create a file called
/etc/cron.allow which contains the names of those allowed to schedule jobs. c. create a
file called /etc/cron.deny containing all regular usernames. d. create two empty files
called /etc/cron.allow and /etc/cron.deny
75. You notice that your server load is exceptionally high during the hours of 10 am to 2 noon
. When investigating the cause, you suspect that it may be a cron job scheduled by one
of your users. What command can you use to determine if your suspicions are correct?
Choose one: a. crontab -u b. crond -u c. crontab -l d. crond -l
76. One of your users, Bob, has created a script to reindex his database. Now he has it
scheduled to run every day at 10:30 am . What command should you use to delete this
job. Choose one: a. crontab -ru bob b. crontab -u bob c. crontab -du bob d. crontab -lu
bob
77. What daemon is responsible for tracking events on your system?
78. What is the name and path of the default configuration file used by the syslogd daemon?
79. You have made changes to the /etc/syslog.conf file. Which of the following commands
will cause these changes to be implemented without having to reboot your computer?
Choose one: a. kill SIGHINT `cat /var/run/syslogd.pid` b. kill SIGHUP `cat
/var/run/syslogd.pid` c. kill SIGHUP syslogd d. kill SIGHINT syslogd
80. Which of the following lines in your /etc/syslog.conf file will cause all critical messages to
be logged to the file /var/log/critmessages? Choose one: a. *.=crit /var/log/critmessages
b. *crit /var/log/critmessages c. *=crit /var/log/critmessages d. *.crit /var/log/critmessages
81. You wish to have all mail messages except those of type info to the
/var/log/mailmessages file. Which of the following lines in your /etc/syslogd.conf file would
accomplish this? Choose one: a. mail.*;mail!=info /var/log/mailmessages b.
mail.*;mail.=info /var/log/mailmessages c. mail.*;mail.info /var/log/mailmessages d.
mail.*;mail.!=info /var/log/mailmessages
82. What is the name and path of the main system log?
83. Which log contains information on currently logged in users? Choose one: a.
/var/log/utmp b. /var/log/wtmp c. /var/log/lastlog d. /var/log/messages
84. You have been assigned the task of determining if there are any user accounts defined
on your system that have not been used during the last three months. Which log file
should you examine to determine this information? Choose one: a. /var/log/wtmp b.
/var/log/lastlog c. /var/log/utmp d. /var/log/messages
85. You have been told to configure a method of rotating log files on your system. Which of
the following factors do you not need to consider? Choose one: a. date and time of
messages b. log size c. frequency of rotation d. amount of available disk space
86. What utility can you use to automate rotation of logs?
87. You wish to rotate all your logs weekly except for the /var/log/wtmp log which you wish to
rotate monthly. How could you accomplish this. Choose one: a. Assign a global option to
rotate all logs weekly and a local option to rotate the /var/log/wtmp log monthly. b. Assign
a local option to rotate all logs weekly and a global option to rotate the /var/log/wtmp log
monthly. c. Move the /var/log/wtmp log to a different directory. Run logrotate against the
new location. d. Configure logrotate to not rotate the /var/log/wtmp log. Rotate it manually
every month.
88. You have configured logrotate to rotate your logs weekly and keep them for eight weeks.
You are running our of disk space. What should you do? Choose one: a. Quit using
logrotate and manually save old logs to another location. b. Reconfigure logrotate to only
save logs for four weeks. c. Configure logrotate to save old files to another location. d.
Use the prerotate command to run a script to move the older logs to another location.
89. What command can you use to review boot messages?
90. What file defines the levels of messages written to system log files?
91. What account is created when you install Linux?
92. While logged on as a regular user, your boss calls up and wants you to create a new user
account immediately. How can you do this without first having to close your work, log off
and logon as root? Choose one: a. Issue the command rootlog. b. Issue the command su
and type exit when finished. c. Issue the command su and type logoff when finished. d.
Issue the command logon root and type exit when finished.
93. Which file defines all users on your system? Choose one: a. /etc/passwd b. /etc/users
c. /etc/password d. /etc/user.conf
94. There are seven fields in the /etc/passwd file. Which of the following lists all the fields in
the correct order? Choose one: a. username, UID, GID, home directory, command,
comment b. username, UID, GID, comment, home directory, command c. UID,
username, GID, home directory, comment, command d. username, UID, group name,
GID, home directory, comment
95. Which of the following user names is invalid? Choose one: a. Theresa Hadden b.
thadden c. TheresaH d. T.H.
96. In order to prevent a user from logging in, you can add a(n) ________at the beginning of
the password field.
97. The beginning user identifier is defined in the _________ file.
98. Which field is used to define the user’s default shell?
99. Bob Armstrong, who has a username of boba, calls to tell you he forgot his password.
What command should you use to reset his command?
100. Your company has implemented a policy that users’ passwords must be reset
every ninety days. Since you have over 100 users you created a file with each username
and the new password. How are you going to change the old passwords to the new
ones? Choose one: a. Use the chpasswd command along with the name of the file
containing the new passwords. b. Use the passwd command with the -f option and the
name of the file containing the new passwords. c. Open the /etc/passwd file in a text
editor and manually change each password. d. Use the passwd command with the -u
option.