25 UNIX Interview Questions

Jan 22

2015This document contains 25 Unix interview questions for BI and DW and analytics professionals. These are very basic questions and generally used to check basic understanding of an individual on UNIX file handling and script management.

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25 UNIX Interview Questions for BI Professional

1. What Client tools (terminal emulator / Telnet client) do you use to work on UNIX?2. What GUI tools (SFTP/FTP/SCP client) you have used to work in UNIX? 3. What if, your client only allows you to connect with UNIX box with secure

connection? Do you know any free GUI tool used in your project? 4. How to check the date of a file?5. How to list the file so we can get last file at last?6. How to check the latest file in set of files?7. How to take the backup of the file so the original file data is safe?8. How to remove junk characters from a file in UNIX. Example cntrl m? 9. What is folder structure of a project? Explain folder structure of your project?10.One fine day you find out that your loads are failing because files are not

available. What will be your course of action? 11.How to find a file in same directory? 12.How to find a file in all the subdirectory? 13.How to do a global file search in UNIX, that means file search in all the places for

that UNIX instance?14. If your load takes flat file before a particular timestamp. Then how you will

change it so it can be loaded. 15.How to identify a UNIX process running in background for any ETL process. 16.How to identify and kill a UNIX process running for an ETL process.17.How to list hidden files in a directory? 18. Is there any way you can connect with SQLplus through UNIX command prompt? 19. In what kind of circumstances you need to require connecting to SQLPlus

through UNIX when it can be done with GUI like Toad, SQL Developer, and SQLPlus?

20.How to verify if your UNIX script is able to connect with database?21.How to capture records returned through database in UNIX script? 22.How to place records or error value in log which has returned through Database? 23.How to debug a UNIX script? 24.How to learn your new project UNIX script and folder structure if you are new to a

project? 25. What is the most common UNIX script structure do you know? Why do you need

to know UNIX script structure?

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25 UNIX Interview Questions with Answer

1. What Client tools (terminal emulator / Telnet client) do you use to work on UNIX?Putty client, emacs editor, ssh secure shell client

2. What type of GUI tools (SFTP/FTP/SCP client) you have used to work in UNIX? ssh secure shell client, WINscp, filezilla

3. What if, your client only allows you to connect with UNIX box with secure connection? Do you know any good GUI tool which can do this for you? 

ssh secure shell client, it’s not a free client.4. How to check the date of a file?

ls –l (long listing gives modified date)5. How to list the file so we can get last file at last (ascending order)?

Do you mean ascending order? Ls –t | tacFor descending order ls -t

6. How to check the latest file in set of same file? ls –ltr filenamexxx*

7. How to take the backup of the file so the original file data is safe?Copy the file to backup directory.

8. How to remove junk characters from a file in UNIX. Example cntrl mhttp://etllabs.com/unix/remove-m-characters-ctrl-m-unix/1944/ - Please refer link.

9. What is folder structure of a typical DW, BI BIG DATA project? Explain the folder structure of your project.

In general – (folders names are always in bold)Inbox->SourceName->Data files & Audit files, Archive, TriggerBin/projectName/Scripts, Config, ParametersBin/projectName/backup (code backup) Outbox->Archive ,     filesProjectName/LogFiles/Archive (for log files)

10.One fine day you find out that your loads are failing because files are not available. What will be your course of action?

Hold ETL schedule.Check with upstream systems if the files are not arrived.Insert the failed ETL jobs and their dependent jobs into schedule once the files are arrived.Permanent solution: Add a trigger (file dependent) to your ETL jobs to avoid this situation.

11.How to find a file in same directory?ls <filename>

12.How to find a file in all the subdirectory? “ls” if you are aware of the subdirectory structure.

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Use “find” command if you are not aware of subdirectory structure, “find” find /var/opt/project -name "filenametosearch"

13.How to do a global file search in UNIX? That means file search in all the places for that UNIX instance?

Use UNIX “find” command.  find / -name "filenametosearch"

14. If your load takes flat file before a particular timestamp. Then how you will change file timestamp so it can be loaded.

touch -d "2015-06-23 12:12:12.000000000" "filenametochange"15.How to identify a unix process running in background for any ETL process.

Use ”ps -e” 16.How to identify and kill a Unix process running for an ETL process.

Use UNIX “ps” to identifyUse “kill” kill -9 <process_id> to kill any process.

17.How to list hidden files in a directory ?You can use ls –a. (Hidden files generally start with “.”)

18. Is there any way you can connect with SQLplus through UNIX command prompt?Its sqlplus syntaxSqlplus user/password@database

19. In what kind of circumstances you need to connect to SQLPlus through UNIX when it can be done with GUI like Toad, SQL Developer, SQLPlus?

When you want execute sqlscripts through a job (Shell script).When you want to dynamically create a sql statement and execute it as part of ETL load.When there is a need to perform reconciliation (status check) in the middle of ETL jobs.

20.How to verify if your UNIX script is able to connect with database? Capture it through $?., If the DB script is not executed properly it will return 0.

21.How to capture records returned through database in UNIX script? If records then definitely to a file, it is also possible to user variables if you are returning finite number of fields.

22.How to place records or error value in log which has returned through Database?Capture it through $?., If the DB script is not executed properly it will return 0.

23.How to debug a UNIX script? Divide the script and label them, evaluate the execution status at every label as a check point.Maintain a prototype / framework of the script for a project, and encourage developers to add their logic to a particular section keeping rest of the processes like error handling, error logging, variable assignment etc intact

24.How to learn your new project UNIX script and folder structure if you are new to a project? 

It’s easy, if you have a script prototype. You can even ask for project script prototype and should be part of development documentation. If not, there is no other way but just walk through the script; Sometimes accurately designed scripts produce great log files and you can understand the process just looking at the log files.

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25.What is the most common UNIX script structure do you know? Why do you need to know UNIX script structure?

http://etllabs.com/unix/unix-shell-scripting-introduction/2760/  Please refer link

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