10 Useful Random Linux Interview Questions and Answers

To a little surprise this time we are not presenting Interview question on any specific subject but on random topics. These question will surely help you in cracking Interviews beside adding to your Knowledge.

Linux Interview Questions

10 Random Linux Questions and Answers

1. Let’s say you maintains a backup on regular basis for the company you are working. The backups are maintained in Compressed file format. You need to examine a log, two months old. What would you suggest without decompressing the compressed file?
Answer : To check the contents of a compressed file without the need of decompressing it, we need to use ‘zcat’. The zcat utility makes it possible to view the contents of a compressed file.
# zcat ­f phpshell­2.4.tar.gz
2. You need to track events on your system. What will you do?
Answer : For tracking the events on the system, we need a daemon called syslogd. The syslogd daemon is useful in tracking the information of system and then saving it to specified log files.

Running ‘syslogd‘ application in terminal generates log file at the location ‘/var/log/syslog‘. The syslogd application is very useful in troubleshooting Linux sytems. A sample log file looks similar to below.

syslongd command

syslongd

3. How will you restrict IP so that the restricted IP’s may not use the FTP Server?
Answer : We can block suspicious IP by integrating tcp_wrapper. We need to enable the parameter “tcp_wrapper=YES” in the configuration file at ‘/etc/vsftpd.conf’. And then add the suspicious IP in the ‘host.deny’ file at location ‘/etc/host.deny’.
Block IP Address

Open ‘/etc/hosts.deny’ file.

# vi /etc/hosts.deny

Add the IP address that you want to block at the bottom of the file.

#
# hosts.deny    This file contains access rules which are used to
#               deny connections to network services that either use
#               the tcp_wrappers library or that have been
#               started through a tcp_wrappers-enabled xinetd.
#
#               The rules in this file can also be set up in
#               /etc/hosts.allow with a 'deny' option instead.
#
#               See 'man 5 hosts_options' and 'man 5 hosts_access'
#               for information on rule syntax.
#               See 'man tcpd' for information on tcp_wrappers
#
vsftpd:172.16.16.1
4. Tell us the difference between Telnet and SSH?
Answer : Telnet and SSH both are communication protocol which are used to manage remote system. SSH is Secured, which requires exchanging of key opposite of telnet which transmit data in plain text, which means telnet is less secure than SSH.
6. You need to stop your X server. When you tries to kill your X server, You got an error message that you cannot quit X server. What will you do?
Answer : When killing a X server, it won’t work normal way like doing ‘/etc/init.d/gdm stop’. We need to execute a special key combination ‘Ctrl+ Alt+ Back Space’ which will force X server to restart.
6. What is the difference between command ‘ping’ and ‘ping6’?
Answer : Both the commands are same and used for the same purpose except that the fact that ping6 is used with ipv6 IP address.
7. You want to search for all the *.tar files in your Home directory and wants to delete all at once. How will you do it?
Answer : We need to use find command with rm command to delete all “.tar” files.
# find /home/ ­name '*.tar' | xargs rm ­rf
8. What is the difference between locate and slocate command?
Answer : The slocate looks for the files that user have access whereas locate will search for the file with updated result.
9. You need to search for the string “Tecmint” in all the “.txt” files in the current directory. How will you do it?
Answer : We need to run the fine command to search for the text “Tecmint” in the current directory, recursively.
# find -­name “*.txt” | xargs grep “Tecmint”
10. You want to send a message to all connected users as “Server is going down for maintenance”, what will you do?
Answer : This can be achieved using the wall command. The wall command sends a message to all connected users on the sever.
# echo please save your work, immediately. The server is going down for Maintenance at 12:30 Pm, sharply. | wall
wall command

wall command

That’s all for now. I will be here again, with an interesting article very soon. Till then stay tuned and connected to Tecmint. Don’t Forget to give your valuable feedback in comment section below.

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59 Responses

  1. Karthees says:

    Very very useful Thank You

  2. Lee says:

    On question #9, why not do:

    grep Tecmint *

    There are many ways to perform that operation in the current directory. However, not including subdirectories, one can type much less by using the above command…

    • Ravi Saive says:

      @Lee,

      The grep Tecmint *, do you think this command will list string “Tecmint“? have you tried it before suggesting, i suggest you to try yourself and see long it takes and what it does before giving final results, for me this command is just a waste of time….and will not work at all..

  3. paulconn says:

    Answer : To check the contents of a compressed file without the need of decompressing it, we need to use ‘zcat’. The zcat utility makes it possible to view the contents of a compressed file.

    This answer implies that zcat doesn’t decompress the file, and uses some fancy algorithm to read compressed data.
    This is not the case, it decompresses the file anyway, then cats the decompressed data.

  4. Vijay says:

    Very Useful ..Thank You :)

  5. Sekhar says:

    Thanku very much can you send more questions to me please

  6. Jeremy says:

    CTRL-ALT-BKSpace is disabled in most of the “desktop” linux distro’s. Best to kill it from CLI.

  7. Sandy says:

    Very useful questions…..Thank you

  8. Ken Roberts says:

    Several comments:

    7: find /home/ -name \*.tar -exec rm {} \;
    – -exec says whenever you find a match, run the command substituting {} with the filename
    – Escape characters that may be interpreted by the shell, like * and ;
    – no need for -rf since these are files and not directories

  9. satish says:

    Hi Avishek,

    your articles help a lot for linux beginners. But I was stuck with few questions.
    I need to list the files from remote ftp server with regular expression as RCCCFHW01N[0-9]{4}2014[0-9]{10}.dat..

    can you help me in listing the files particular 2014 in which remote server holds files from different years.

  10. Amalayar says:

    This is so baloney. Where is the Linux Bible ebook that I can download?

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