Basic shell scripting questions

1. How do you find out what’s your shell? – echo $SHELL


2. What’s the command to find out today’s date? – date

3. What’s the command to find out users on the system? – who

4. How do you find out the current directory you’re in? – pwd

5. How do you remove a file? – rm

6. How do you remove a – rm -rf

7. How do you find out your own username? – whoami

8. How do you send a mail message to somebody? – mail somebody@techinterviews.com -s ‘Your subject’ -c ‘cc@techinterviews.com‘

9. How do you count words, lines and characters in a file? – wc

10. How do you search for a string inside a given file? – grep string filename

11. How do you search for a string inside a directory? – grep string *

12. How do you search for a string in a directory with the subdirectories recursed? – grep -r string *

13. What are PIDs? – They are process IDs given to processes. A PID can vary from 0 to 65535.

14. How do you list currently running process? – ps

15. How do you stop a process? – kill pid

16. How do you find out about all running processes? – ps -ag

17. How do you stop all the processes, except the shell window? – kill 0

18. How do you fire a process in the background? – ./process-name &

19. How do you refer to the arguments passed to a shell script? – $1, $2 and so on. $0 is your script name.

20. What’s the conditional statement in shell scripting? – if {condition} then … fi

21. How do you do number comparison in shell scripts? – -eq, -ne, -lt, -le, -gt, -ge

22. How do you test for file properties in shell scripts? – -s filename tells you if the file is not empty, -f filename tells you whether the argument is a file, and not a directory, -d filename tests if the argument is a directory, and not a file, -w filename tests for writeability, -r filename tests for readability, -x filename tests for executability

23. How do you do Boolean logic operators in shell scripting? – ! tests for logical not, -a tests for logical and, and -o tests for logical or.

24. How do you find out the number of arguments passed to the shell script? – $#

25. What’s a way to do multilevel if-else’s in shell scripting? – if {condition} then {statement} elif {condition} {statement} fi

26. How do you write a for loop in shell? – for {variable name} in {list} do {statement} done

27. How do you write a while loop in shell? – while {condition} do {statement} done

28. How does a case statement look in shell scripts? – case {variable} in {possible-value-1}) {statement};; {possible-value-2}) {statement};; esac

29. How do you read keyboard input in shell scripts? – read {variable-name}

30. How do you define a function in a shell script? – function-name() { #some code here return }

31. How does getopts command work? – The parameters to your script can be passed as -n 15 -x 20. Inside the script, you can iterate through the getopts array as while getopts n:x option, and the variable $option contains the value of the entered option.

To check Linux page I/P and page O/P errors

There are few commands to check the Page i/p and page o/p errors in Linux m/c.

1. vmstat -s  // this command will list the page i/p and o/p values at one time. No option for regular interval.
2. sar -B 1 5  // this will display you the page values at regular intervals which you mentioned the delay.
3. iostat 1 5   // this will aslo display you the page values at regular intervals which you mentioned the delay.

To display size of a page in bytes, enter:

$ getconf PAGESIZE

OR
$ getconf PAGE_SIZE

Output:

4096

Mommy, I found it! — 15 Practical Linux Find Command Examples

Mommy, I found it! — 15 Practical Linux Find Command Examples

GOOGLE PRE-SCREEN TEST!!

Below are the few questions which I was asked by GOOGLE pre-screen test. hope it should be helpful.

TCP/IP

1. How many bytes in a MAC address?
2. Which protocol is used by PING command?
3. How many hosts are available in /23 subnet?

UNIX

1. What is the purpose for setting STICKY BIT on directories?
2. What is the default signal send by KILL command?
3. Which UNIX part is taken care of storing files information in INODE?

Will update here once everything came to know.

Procedure to mount remote windows partition (NAS share) on Linux

Procedure to mount remote windows partition (NAS share) on Linux


1) Make sure you have following information:

==> Windows username and password to access share name

==> Sharename (such as //server/share) or IP address

==> root level access on Linux


2) Login to Linux as a root user (or use su command)


3) Create the required mount point:

# mkdir -p /mnt/ntserver

4) Use the mount command as follows:

# mount -t cifs //ntserver/download -o username=vivek,password=myPassword /mnt/ntserver