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Linux Job Interview Questions

June 1, 2006

Linux Tips
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What command should you use to check your filesystem?

Answer: fsck
The fsck command is used to check the integrity of the filesystem on your disk.

You want to print out a text file called vacations however the lines are of varying length. What text filter could you use to even out the length of the lines?

Answer: fmt
The fmt text utility attempts to make all the lines the same lenght by joining or splitting lines.

You need to locate a file called salesdata that one of your user’s created in his home directory but you do not know which one. How could you use the find command to locate this file?

Answer: find /home -name salesdata
When using the find command to locate a file by name you must specify the starting place in the directory heirarchy and the -name option to specify the file to search for.

What command would you type to use the cpio to create a backup called backup.cpio of all the users’ home directories?

Answer: 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.

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.

Answer: file
The gzip utility cannot compress multiple files in a single operation.

You have three files in the /home/ben/memos directory called letters, tom, betty. How could you determine each file’s type by issuing only one command?

Answer: file letters tom betty
The file utility will display the file’s type for each filename that is passed as an argument.

In order to display the last five commands you have entered using the fc command, you would type ___________.

Answer: fc -5
The fc command can be used to edit or rerun commands you have previously entered. To specify the number of commands to list, use -n.

Each command has two types of output. There are standard output and standard __________.

Answer: error
By default, each command sends its result as standard output and any error messages as standard error.

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

Answer: 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
B) FSSTND
C) DNS
D) NNTP
E) NFS

Answer: 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.

What would you type to send the last 20 lines of a text file to STDIN?

A) end -n 20 filename
B) last -n 20 filename
C) head -20 filename
D) end -20 filename
E) tail -20 filename

Answer: E – Use the command tail -20 filename to see the last 20 lines of a file. The answers for a and d both point to an invalid command. The answer for b points to a valid command. Typing this answer in with a valid file name will even give you some output. However, the last command tells you who is logged in, it does not actually list the contents of any file named in the command. The answer for c, the head command, is used to look at the beginning of a file, not the end.

Which command works in almost all distributions to create a boot disk?

A) mkboot
B) make bootdsk
C) make boot
D) mkbootdsk
E) mkbootdisk

Answer: E – The mkbootdisk command creates a boot disk. Answers b and c are incorrect. The make package is used to compile software, not create boot disks. Answers a and d point to invalid commands.

Which command do you use to change runlevels?

A) initlevel
B) runlevel
C) level
D) run
E) init

Answer: E – The command used to change runlevels is init. Answers a, c, and d point to invalid commands. Answer b is a valid command, but does not set the current runlevel. The runlevel command displays the current runlevel, and the one that was used directly before entering this one.

You have a new, empty hard drive that you will use for Linux. What is the first step you use.
Choose one:

a. Create an extended partition to be used for data.
b. Format the hard drive to use the ext2 filesystem.
c. Create a swap partition of type 82.
d. Create a primary partition using fdisk.

Answer: d
You must always first create a primary partition. Operating systems, including Linux, can only be booted from a primary partition.

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.

Answer: d
You can use the prerotate command to run a script before logs are rotated. You could have this script move the older logs to another location before rotation occurs.

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.

Answer: d
When you use &> for redirection, it redirects both the standard output and standard error. The output would be saved to the file cat.

You have a directory with the following permissions
drw-rw–w- 1 root admin 7202 Sep 17 9:10 administration
and need to give everyone except root read only access to it. Which of the following commands will accomplish this?
Choose one:

a. chmod uo=r administration
b. chmod ug+r administration
c. chmod uo+r administration
d. chmod ug=r administration

Answer: d
When using symbols, the equal sign explicitly sets permissions and revokes any pre-existing permissions.

You want to know how much space is being occupied by your user’s home directories. Which of the following will provide you with this information?
Choose one:

a. du -l /home
b. du -b /home
c. du -m /home
d. du -c /home

Answer: d
Using the -c option with the du command will show the grand total of used space for the designated directory.

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

Answer: d
This would run at 15 minutes after the hour on every Monday, Wednesday, and Friday of every month no matter what the date.

You need to see the last fifteen lines of the files dog, cat and
horse. What command should you use?

Answer: 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?

Answer: 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.

Answer: zcat
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?

Answer: which
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.

Answer: whatis
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.

Answer: 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 ___________.

Answer: type
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?

Answer: top
The top utility shows a listing of all running processes that is
dynamically updated.

Where is standard output usually directed?

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

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

Answer: tar
You can use the z modifier with tar to compress your archive at the
same time as creating it.

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

Answer: 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?

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

What daemon is responsible for tracking events on your system?

Answer: syslogd
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?

Answer: split
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?

Answer: 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?

Answer: root
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?

Answer: repquota
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.

In order to run fsck on the root partition, the root partition must
be mounted as ___________.

Answer: 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?

Answer: pwconv
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?

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

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?

Answer: no
The kmem group manages direct access to kernel memory and is necessary
for your system’s health.

What text filter can you use to display a multi-page file and place
numbers at the beginning of each line.
DirContents
Using the > will redirect the output of the ls /etc command to the
file DirContents.

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

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

You have two files each ten lines long. What text filter could you
use to combine the two files so that each line of the output contains
the corresponding line from each file?

Answer: join
The join text filter will display one line for each pair of input
lines from two files.

You have two files in two different directories with the same
inode. What type of link is involved?
“,1] ); //–>
Answer: nl
The nl text filter will divide a file into logical pages and number each line.

Question 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 ___________?

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

In order to apply a filesystem to your new partitions you must
format them. What command would you use to create the ext2 filesystem?

Answer: mke2fs
The mke2fs command creates the new filesystem on your partition.

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.

Answer: 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.

In order to create a file called DirContents containing the
contents of the /etc directory you would type ____________.

Answer: ls /etc > DirContents
Using the > will redirect the output of the ls /etc command to the
file DirContents.

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

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

You have two files each ten lines long. What text filter could you
use to combine the two files so that each line of the output contains
the corresponding line from each file?

Answer: join
The join text filter will display one line for each pair of input
lines from two files.

You have two files in two different directories with the same
inode. What type of link is involved?
/interview-questions/type.asp?iType\u003d83&offset\u003d20

“,0] ); D([“ma”,[1,”

Linux JOB Interview questions.doc
61K View as HTML Scanning for viruses…

“,”10b484103aee0819″] ] ); D([“ce”]); //–>
Answer: hard
Hard links all have the same inode number, unlike symbolic links.

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

Answer: 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.

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10 comments

  1. thanx for sharing
    its very useful to upcoming sys admin
    thanx again for the great work


  2. ya it was fantastic, and a good guide for the beginners.


  3. Should add this question: How to check logrotate status

    http://www.linuxask.com/questions/how-to-check-the-logrotate-status

    Not many guy know.


  4. Surely great job.well done.Extending all my support!


  5. Great job …thanks..;)


  6. Nice post but need more polishing…….


  7. Thank you for this =)


  8. Nice work man keep it up ….!!!!

    if u have any more quest and ans plz e-mail me

    Thanks,
    Parvez Khan


  9. very useful !!!


  10. Just what are people’s experiences associated with
    employment advancement within the security area?
    I’d gradually like to turn out doing work in the
    law enforcement force and I am pondering whether I could just go
    right into that or test the waters with something less intense.
    Has anyone started off in basic security and ended up working with the authorities?



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