Linux Technical Interview Questions

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linuxWhat command allows you to set a processor-intensive job to use less CPU time?

A) ps
B) nice
C) chps
D) less
E) more

Answer: B – The nice command is used to change a job’s priority level, so that it runs slower or faster. Answers a, d, and e are valid commands but are not used to change process information. Answer c is an invalid command.

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.

Answer: b
You can use the su command to imitate any user including root. You will be prompted for the password for the root account. Once you have provided it you are logged in as root and can do any administrative duties.

In order o run fsck on the root partition, the root partition must be mounted as readonly
You cannot run fsck on a partition that is mounted as read-write.

In order to improve your system’s security you decide to implement shadow passwords. What command should you use?


The pwconv command creates the file /etc/shadow and changes all passwords to ‘x’ in the /etc/passwd file.

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?

passwd boba

The passwd command is used to change your password. If you do not specify a username, your password will be changed.

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 ___________?

Both the top and nice utilities provide the capability to change the priority of a running process.

What command should you type to see all the files with an extension of ‘mem’ listed in reverse alphabetical order in the /home/ben/memos directory.

ls -r /home/ben/memos/*.mem

The -c option used with ls results in the files being listed in chronological order. You can use wildcards with the ls command to specify a pattern of filenames.

What file defines the levels of messages written to system log files?

To determine the various levels of messages that are defined on your system, examine the kernel.h file.

What command is used to remove the password assigned to a group?

gpasswd -r

The gpasswd command is used to change the password assigned to a group. Use the -r option to remove the password from the group.
What command would you type to use the cpio to create a backup called backup.cpio of all the users’ home directories?
find /home | cpio -o > backup.cpio

The find command is used to create a list of the files and directories contained in home. This list is then piped to the cpio utility as a list of files to include and the output is saved to a file called backup.cpio.

What can you type at a command line to determine which shell you are using?

echo $SHELL

The name and path to the shell you are using is saved to the SHELL environment variable. You can then use the echo command to print out the value of any variable by preceding the variable’s name with $. Therefore, typing echo $SHELL will display the name of your shell.

What type of local file server can you use to provide the distribution installation materials to the new machine during a network installation?
A) Inetd

E – You can use an NFS server to provide the distribution installation materials to the machine on which you are performing the installation. Answers a, b, c, and d are all valid items but none of them are file servers. Inetd is the superdaemon which controls all intermittently used network services. The FSSTND is the Linux File System Standard. DNS provides domain name resolution, and NNTP is the transfer protocol for usenet news.

If you type the command cat dog & > cat what would you see on your display? Choose one:

a. Any error messages only.
b. The contents of the file dog.
c. The contents of the file dog and any error messages.
d. Nothing as all output is saved to the file cat.


When you use & > for redirection, it redirects both the standard output and standard error. The output would be saved to the file cat.
You are covering for another system administrator and one of the users asks you to restore a file for him. You locate the correct tarfile by checking the backup log but do not know how the directory structure was stored. What command can you use to determine this?
Choose one:

a. tar fx tarfile dirname
b. tar tvf tarfile filename
c. tar ctf tarfile
d. tar tvf tarfile


The t switch will list the files contained in the tarfile. Using the v modifier will display the stored directory structure.
You have the /var directory on its own partition. You have run out of space. What should you do? Choose one:

a. Reconfigure your system to not write to the log files.
b. Use fips to enlarge the partition.
c. Delete all the log files.
d. Delete the partition and recreate it with a larger size.


The only way to enlarge a partition is to delete it and recreate it. You will then have to restore the necessary files from backup.
You have a new application on a CD-ROM that you wish to install. What should your first step be?
Choose one:
a. Read the installation instructions on the CD-ROM.
b. Use the mount command to mount your CD-ROM as read-write.
c. Use the umount command to access your CD-ROM.
d. Use the mount command to mount your CD-ROM as read-only.


Before you can read any of the files contained on the CD-ROM, you must first mount the CD-ROM.

When you create a new partition, you need to designate its size by defining the starting and ending _____________.

When creating a new partition you must first specify its starting cylinder. You can then either specify its size or the ending cylinder.
You need to see the last fifteen lines of the files dog, cat and horse. What command should you use?

tail -15 dog cat horse

The tail utility displays the end of a file. The -15 tells tail to display the last fifteen lines of each specified file.

Who owns the data dictionary?

The SYS user owns the data dictionary. The SYS and SYSTEM users are created when the database is created.
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.

The zcat utility allows you to examine the contents of a compressed file much the same way that cat displays a file.

You suspect that you have two commands with the same name as the command is not producing the expected results. What command can you use to determine the location of the command being run?


The which command searches your path until it finds a command that matches the command you are looking for and displays its full path.

You locate a command in the /bin directory but do not know what it does. What command can you use to determine its purpose.


The whatis command displays a summary line from the man page for the specified command.
You wish to create a link to the /data directory in bob’s home directory so you issue the command ln /data /home/bob/datalink but the command fails. What option should you use in this command line to be successful.
Use the -F option

In order to create a link to a directory you must use the -F option.

When you issue the command ls -l, the first character of the resulting display represents the file’s ___________.


The first character of the permission block designates the type of file that is being displayed.

What utility can you use to show a dynamic listing of running processes? __________

The top utility shows a listing of all running processes that is dynamically updated.
Where is standard output usually directed?

to the screen or display

By default, your shell directs standard output to your screen or display.

You wish to restore the file memo.ben which was backed up in the tarfile MyBackup.tar. What command should you type?

tar xf MyBackup.tar memo.ben

This command uses the x switch to extract a file. Here the file memo.ben will be restored from the tarfile MyBackup.tar.

You need to view the contents of the tarfile called MyBackup.tar. What command would you use?

tar tf MyBackup.tar

The t switch tells tar to display the contents and the f modifier specifies which file to examine.

You want to create a compressed backup of the users’ home directories. What utility should you use?


You can use the z modifier with tar to compress your archive at the same time as creating it.
What daemon is responsible for tracking events on your system?

The syslogd daemon is responsible for tracking system information and saving it to specified log files.

You have a file called phonenos that is almost 4,000 lines long. What text

filter can you use to split it into four pieces each 1,000 lines long?

The split text filter will divide files into equally sized pieces. The default length of each piece is 1,000 lines.

You would like to temporarily change your command line editor to be vi. What command should you type to change it?
set -o vi

The set command is used to assign environment variables. In this case, you are instructing your shell to assign vi as your command line editor. However, once you log off and log back in you will return to the previously defined command line editor.
What account is created when you install Linux?


Whenever you install Linux, only one user account is created. This is the superuser account also known as root.

What command should you use to check the number of files and disk space used and each user’s defined quotas?


The repquota command is used to get a report on the status of the quotas you have set including the amount of allocated space and amount of used space.



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