Linux - INTERVIEW QUESTIONS AND ANSWERS

Vi:

1.What are editors in Linux/UNIX OS?

2.A different list of editors available in Linux OS?

3.What is Vi editor?

4.How to create a new file with Vi editor?

5.How to save and exit the file in vi editor?

6.How to move a page forward in the file?

7.How to move a page backward in the file?

8.How to move half page forward and backward in the file?

9.How to search for the string in a file?

10.How to search for a string from the bottom of the file?

11.How to insert content using vi editor?

12.How to delete a line in vi editor?

13.How to delete multiple lines in vi editor?

14.How to copy and paste in vi editor?

15.Vi editor cheat sheet?

umask:

1.What is umask in Linux and UNIX machines?

2.What is the use of umask in Linux servers?

3.What are the original file and directory permissions in Linux machine?

4.What is umask default value?

5.How to change the umask value?

6.What are the configuration files related to umask values?

Head &

1.How to list top 10 lines of a file?

2.How to list the top 4 lines of a file?

3.How to list the bottom 3 lines of a file using the tail command?

4.What is the use of tail -f command?

5.How to see continuous updates of a file?

more & less:

1.How to display the content of a using more command?

2.How to display the content of a using less command?

3.What are the differences between the cat, more & less commands?

find:

1.How to search for a file in Linux/UNIX system?

2.Command to search for a file based on its name in Linux?

3.How to search for files starting with "ab" characters?

4.find command syntax to search for a file in particular directory?

5.How to search for files based on the size limit in Linux?

6.How to list out the files which are accessed 2 days ago in a directory?

7.How to list out the files which are modified 4 days ago in Linux?

8.Search for the files which are not owned by any user in /etc/passwd?

9.How to Search for files starting with letters "ab" and display their content? or number of lines in those files?

10.In Linux, list out the files who's status is changed 1 day ago?

cut:

1.Write a command to display the third and fourth character from each line of a file?

2.Write a command to display the characters from 10 to 20 from each line of a file?

3.Write a command to display the first 10 characters from each line of a file?

4.Write a command to display from the 10th character to the end of the line?

5.The fields in each line are delimited by colon Write a command to display third field from each line of a file?

6.Write a command to print the fields from 1 to 4 from each line of a file?

7.Write a command to print the first 5 fields from each line?

8.Write a cut command to extract the username from 'who am i' command? 

User management:

Useradd:

1.How to create a new user in Linux machine?

2.What is the difference between primary group and secondary group of a user?

3.What is the userid value of a user? detail about reserved userid values?

4.Where does the user account information is stored on linux system?

5.In linux server, where does the user password information is stored?

6.Can we have a username in capital letters in Linux machine?

7.Where does the default attributes of a user stored?

Usermod:

1.How to modify user credential details? Which command used to modify user account information?

2.How to change primary and secodary groups of a user?

3.How to add comment to an account?

4.How to lock a user account? and in which cases we lock it?

5.How to unlock the user account in linux?

6.How to modify a username for a user account in linux?

7.How to modify the userid for a user account?

8.How to check the expiry information of user account?

9.How to modify the expiry information of user?

Userdel:

1.How to delete a user account from Linux server?

2.Delete a user account along with its home directory?

3.What if we accidentally deleted a user account? What will happen and how do we solve those issues?

4.What are the things to keep in mind or checks to be done, before deleting a user account?

5.After deleting a user account, do we have to perform any housekeeping activities?

Group management:

groupadd:

1.What is group?

2.How to create a new group on server?

3.What is gid means for a group? what are its value range?

4.How and where we can check the group details exists or not? and why?

groupmod:

1.How to modify the group information?

groupdel:

1.How to delete a group from Linux system?

2.What are the pre-checks before deleting a group account?

3.What if we accidentally delete a group account?

4.Once a group is deleted, do we have to do any housekeeping works? I.e, cleaning up any pending files etc?

Configuration files:

1.What is /etc/motd configuration file used for?

2.What does /etc/bashrc configuration file contains?

3.What is /etc/profile configuration file for?

4.What is .bash_profile,.bash_logout, .bash_history and .bashrc is used for?

monitoring users:

1.How to check the logged in user details?

2.What is the difference between whoami & id command in Linux?

3.How do I know the server reboots information? such as, How many times & the date of server reboots etc?

4.How can I check a particular user login & logout details?

5.What does the finger command displays?

6.How do I know which all users are logged into particular server as of now?

7.How can we know, system load?

8.What if we want to understand the last system reboot details?

9.What is the difference between w, who and uptime commands?

chage:

1.How to disable password ageing for a particular user?

2.How to enable password expiry date of a particular user?

3.How to Set the Account expiry date in the format ‘YYYY-MM-DD’?

4.How to Set the password expiry warning message?

5.How to force a user to change password in the next login?

FTP section:

FTP Introduction:

1.What is FTP? In which scenarios we can use this protocol?

2.What is difference between FTP client and FTP server?

FTP connectivity:

1.What is active FTP mode of connectivity?

2.What is passive FTP mode of connectivity?

3.Describe the differences between active and passive mode of FTP communication?

4.In what scenario, we need to ftp the files from one server to another server?

FTP Configuration:

1.What are the packages to be installed in linux for FTP server?

2.What is the name of the ftp daemon, which is running in the back ground?

3.What are port numbers at which ftp communication will happen?

4.List out ftp configuration files on a linux machine?

5.What is the home directory of ftp user?

6.Step by step understanding on, how to configure the ftp server on RHEL machine?

FTP client configuration:

1.How to configure FTP client in RHEL machine?

2.What are list of commands from FTP client end for moving the files in and out of the server?

3.Windows acting as FTP client? FTP commands execution from FTP client. 

4.How to configure the FTP server for uploading and downloading the files?

5.How to provide root access to the FTP server?

NFS:

NFS introduction:

1.What is NFS?

2.Using NFS, can we share files and directories between cross OS platforms?

3.What are the different versions of NFS servers?

4.What are new features of NFS 4 over NFS 3?

Working with NFS:

1.How NFS works?

2.List out different NFS daemons and their functionality?

Configuring NFS server:

1.On a Linux machine,  how can we check if NFS server is installed or not? packages to be installed?

2.What are the NFS configuration files and daemons?

3.What is the default port number of NFS? can we change that NFS default port number?

4.How to configure NFS server? Step by Step explanation?

5.Step by Step explanation of NFS client configuration on Linux?

6.Explanation of /etc/exports? Examples...

uname

Let's assume, we have logged into a machine's terminal windows and want to check below details...

1.How to check the architecture of terminal machine or server?

2.How to check the type of operating system of the server?

3.Command to check the kernel release of the system?

4.Can we check the system host name information using "uname" command?

5.How to check the complete system information?

Cat:

1.What are the practical use cases of cat command?

2.How to create a new file with cat command?

3.Command to add new lines to existing file?

4.Can we use cat command to copy a file's content to another file?

5.How to display multiple file's output using cat command?

6.Instead of displaying the multiple files output on terminal, redirect it to a file. how we can

achieve this?

7.Command to display the line numbers of a file?

8.Command to display line numbers of a file but avoid empty files?

9.Is it possible to display 2 files output mixed with terminal input content?

10.Is it possible to empty a file using cat command?

11.How can I see cat command options?

12.During which situations, we use copy command as Linux administrator?

13.How to make a copy of a file into same directory?

14.How to copy a file to another file but avoid overwriting if it's already existing?

15.How to copy a file from current directory to new directory?

16.How to copy multiple files from one directory to another directory?

17.How to force the copying operation?

18.How to copy entire directory to another directory?

19.How to make a directory as sub-directory in another target directory? For ex: dir1 should be sub-directory for dir2.

20.Which flag or option of cp command can be used to prompt the file overwriting?

21.How to copy the file from one location to another location without changing the file attributes?

22.What is the limitation of cat command in the form of copying the content to another file?

23.What is the use cases of mv command?

24.Can we rename a particular directory using mv command?

25.How to rename a file in a directory?

26.How to move a file from one directory to another directory?

27.How to move one directory files to another directory?

28.How to make a directory as sub-directory to another? For ex: dir1 should be sub-directory

for dir2.

29.How to move a file to a target directory only when source file is newer than the target one?

mv command:

1.What is the use cases of mv command?

2.Can we rename a particular directory using mv command?

3.How to rename a file in a directory?

4.How to move a file from one directory to another directory?

5.How to move one directory files to another directory?

6.How to make a directory as sub-directory to another? For ex: dir1 should be sub-directory for dir2.

7.How to move a file to a target directory only when source file is newer than the target one?

wc:

1.What are some real time situations in which we use "wc" command?

2.How to check lines, words and characters of a file?

3.How to count the words in a file or an input content?

4.Which command we use for counting number of lines in a file?

5.How to print the byte or character count of a file?

6.What is the command to print length of longest line in a file?

rmdir & rm:

1.How to remove an empty directory?

2.How to remove an non empty directory or a directory with sub directories and files in it?

3.How to remove a file in a directory?

4.How to remove a file forcefully?

5.Why we need to force remove a file? What are different scenarios?

6.Command to remove multiple files at a time?

7.I have couple of files in a directory and few of them have same extensions. How can we remove those files with same extensions?

Su command

1.How to switch from one user to another user in Linux?

2.How to switch back to previous user account from present one? Or come out of present use session?

3.Why we need to switch from one user account to another user account?

4.How to switch to new user and landing into user’s home directory?

5.How can we change the new user SHELL form the default when logging in?

6.How can we switch to root user account in Linux environment?

ls:

1.How to list the files and directories in Linux/UNIX?

2.How to list the files and directories in the reverse order?

3.How to list the files with time stamp and in reverse timestamp in Linux?

4.How to list the files with size in human reversible format?

5.How to list the files with size in bytes?

6.Command to display the hidden files of a directory?

7.How list the files with their inode numbers in Linux?

cal:

1.How to display current date on UNIX terminal?

2.Command to display any particular day month and year?

3.How to display Julian dates on UNIX terminal?

4.Command syntax to display calender for the year 1991?

5.cal command syntax to display current month and previous and next month calenders?

6.Command to display current month calender sheet with sunday as starting day of the week?

Date:

1.What is the date command is used for?

2.What are "date" command options that we use most frequently?

3.What are the different formating controls with "date" command?

4.How to print the date based on given date string? for ex: 2nd July 2016

5.Assume we have a file with date strings in it. how can we display proper date formats?

6.How can we know date of next friday?

7.We have a file on Linux machine and want to know the last modified date?

8.How to set the system time and date of Linux machine from terminal?

9.More date command examples with output format options?

touch:

1.What are some of practical(real time) use cases of touch command?

2.How to create an empty file?

3.How can we update the modified time of the file without modifying anything in it?

4.Command syntax to create multiple empty files through linux terminal window?