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Sysadmin interview questions

Category: Unix/Linux Questions    |    2 views    |    Add a Comment

  1. What is a level 0 backup?
  2. What is an incremental backup?
  3. What steps are required to perform a bare-metal recovery?
  4. Name key files or directories on a UNIX system that should always be backed up.
  5. Name key files or directories on a Windows system that should always be backed up.
  6. What is RAID 0?
  7. What is RAID 0+1? Why is it better than 0?
  8. What is RAID-5?
  9. Why would you NOT want to encapsulate a root directory with Veritas?
  10. What is concatenation?
  11. What is striping?
  12. What is a spindle?

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OS interview questions

Category: Unix/Linux Questions    |    5 views    |    Add a Comment

  1. What is MUTEX ?
  2. What isthe difference between a ‘thread’ and a ‘process’?
  3. What is INODE?
  4. Explain the working of Virtual Memory.
  5. How does Windows NT supports Multitasking?
  6. Explain the Unix Kernel.
  7. What is Concurrency? Expain with example Deadlock and Starvation.
  8. What are your solution strategies for “Dining Philosophers Problem” ?
  9. Explain Memory Partitioning, Paging, Segmentation.
  10. Explain Scheduling.
  11. Operating System Security.
  12. What is Semaphore?
  13. Explain the following file systems : NTFS, Macintosh(HPFS), FAT .
  14. What are the different process states?
  15. What is Marshalling?
  16. Define and explain COM?
  17. What is Marshalling?
  18. Difference - Loading and Linking ?

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PHP interview questions

Category: Unix/Linux Questions    |    4 views    |    Add a Comment

  1. What does a special set of tags <?= and ?> do in PHP? - The output is displayed directly to the browser.
  2. What’s the difference between include and require? - It’s how they handle failures. If the file is not found by require(), it will cause a fatal error and halt the execution of the script. If the file is not found by include(), a warning will be issued, but execution will continue.
  3. I am trying to assign a variable the value of 0123, but it keeps coming up with a different number, what’s the problem? - PHP Interpreter treats numbers beginning with 0 as octal. Look at the similar PHP interview questions for more numeric problems.
  4. Would I use print “$a dollars” or “{$a} dollars” to print out the amount of dollars in this example? - In this example it wouldn’t matter, since the variable is all by itself, but if you were to print something like “{$a},000,000 mln dollars”, then you definitely need to use the braces.
  5. How do you define a constant? - Via define() directive, like define (”MYCONSTANT”, 100);
  6. How do you pass a variable by value? - Just like in C++, put an ampersand in front of it, like $a = &$b
  7. Will comparison of string “10″ and integer 11 work in PHP? - Yes, internally PHP will cast everything to the integer type, so numbers 10 and 11 will be compared.
  8. When are you supposed to use endif to end the conditional statement? - When the original if was followed by : and then the code block without braces.
  9. Explain the ternary conditional operator in PHP? - Expression preceding the ? is evaluated, if it’s true, then the expression preceding the : is executed, otherwise, the expression following : is executed.
  10. How do I find out the number of parameters passed into function? - func_num_args() function returns the number of parameters passed in.
  11. If the variable $a is equal to 5 and variable $b is equal to character a, what’s the value of $$b? - 100, it’s a reference to existing variable.
  12. What’s the difference between accessing a class method via -> and via ::? - :: is allowed to access methods that can perform static operations, i.e. those, which do not require object initialization.
  13. Are objects passed by value or by reference? - Everything is passed by value.
  14. How do you call a constructor for a parent class? - parent::constructor($value)
  15. What’s the special meaning of __sleep and __wakeup? - __sleep returns the array of all the variables than need to be saved, while __wakeup retrieves them.
  16. Why doesn’t the following code print the newline properly?    <?php
                $str = ‘Hello, there.\nHow are you?\nThanks for visiting TechInterviews’;
                print $str;
        ?>
    Because inside the single quotes the \n character is not interpreted as newline, just as a sequence of two characters - \ and n.
  17. Would you initialize your strings with single quotes or double quotes? - Since the data inside the single-quoted string is not parsed for variable substitution, it’s always a better idea speed-wise to initialize a string with single quotes, unless you specifically need variable substitution.
  18. How come the code <?php print “Contents: $arr[1]”; ?> works, but <?php print “Contents: $arr[1][2]”; ?> doesn’t for two-dimensional array of mine? - Any time you have an array with more than one dimension, complex parsing syntax is required. print “Contents: {$arr[1][2]}” would’ve worked.
  19. What is the difference between characters \023 and \x23? - The first one is octal 23, the second is hex 23.
  20. With a heredoc syntax, do I get variable substitution inside the heredoc contents? - Yes.
  21. I want to combine two variables together:

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Oracle on Linux/Unix questions

Category: Unix/Linux Questions    |    3 views    |    Add a Comment

  1. How many memory layers are in the shared pool?
  2. How do you find out from the RMAN catalog if a particular archive log has been backed-up?
  3. How can you tell how much space is left on a given file system and how much space each of the file system’s subdirectories take-up?
  4. Define the SGA and how you would configure SGA for a mid-sized OLTP environment? What is involved in tuning the SGA?
  5. What is the cache hit ratio, what impact does it have on performance of an Oracle database and what is involved in tuning it?
  6. Other than making use of the statspack utility, what would you check when you are monitoring or running a health check on an Oracle 8i or 9i database?
  7. How do you tell what your machine name is and what is its IP address?
  8. How would you go about verifying the network name that the local_listener is currently using?
  9. You have 4 instances running on the same UNIX box. How can you determine which shared memory and semaphores are associated with which instance?
  10. What view(s) do you use to associate a user’s SQLPLUS session with his o/s process?
  11. What is the recommended interval at which to run statspack snapshots, and why?
  12. What spfile/init.ora file parameter exists to force the CBO to make the execution path of a given statement use an index, even if the index scan may appear to be calculated as more costly?
  13. Assuming today is Monday, how would you use the DBMS_JOB package to schedule the execution of a given procedure owned by SCOTT to start Wednesday at 9AM and to run subsequently every other day at 2AM.
  14. How would you edit your CRONTAB to schedule the running of /test/test.sh to run every other day at 2PM?
  15. What do the 9i dbms_standard.sql_txt() and dbms_standard.sql_text() procedures do?
  16. In which dictionary table or view would you look to determine at which time a snapshot or MVIEW last successfully refreshed?
  17. How would you best determine why your MVIEW couldn’t FAST REFRESH?
  18. How does propagation differ between Advanced Replication and Snapshot Replication (read-only)?
  19. Which dictionary view(s) would you first look at to understand or get a high-level idea of a given Advanced Replication environment?
  20. How would you begin to troubleshoot an ORA-3113 error?
  21. Which dictionary tables and/or views would you look at to diagnose a locking issue?
  22. An automatic job running via DBMS_JOB has failed. Knowing only that “it’s failed”, how do you approach troubleshooting this issue?
  23. How would you extract DDL of a table without using a GUI tool?
  24. You’re getting high “busy buffer waits” - how can you find what’s causing it?
  25. What query tells you how much space a tablespace named “test” is taking up, and how much space is remaining?
  26. Database is hung. Old and new user connections alike hang on impact. What do you do? Your SYS SQLPLUS session IS able to connect.
  27. Database crashes. Corruption is found scattered among the file system neither of your doing nor of Oracle’s. What database recovery options are available? Database is in archive log mode.
  28. Illustrate how to determine the amount of physical CPUs a Unix Box possesses (LINUX and/or Solaris).
  29. How do you increase the OS limitation for open files (LINUX and/or Solaris)?
  30. Provide an example of a shell script which logs into SQLPLUS as SYS, determines the current date, changes the date format to include minutes & seconds, issues a drop table command, displays the date again, and finally exits.
  31. Explain how you would restore a database using RMAN to Point in Time?
  32. How does Oracle guarantee data integrity of data changes?
  33. Which environment variables are absolutely critical in order to run the OUI?
  34. What SQL query from v$session can you run to show how many sessions are logged in as a particular user account?
  35. Why does Oracle not permit the use of PCTUSED with indexes?
  36. What would you use to improve performance on an insert statement that places millions of rows into that table?
  37. What would you do with an “in-doubt” distributed transaction?
  38. What are the commands you’d issue to show the explain plan for “select * from dual”?
  39. In what script is “snap$” created? In what script is the “scott/tiger” schema created?
  40. If you’re unsure in which script a sys or system-owned object is created, but you know it’s in a script from a specific directory, what UNIX command from that directory structure can you run to find your answer?
  41. How would you configure your networking files to connect to a database by the name of DSS which resides in domain icallinc.com?
  42. You create a private database link and upon connection, fails with: ORA-2085: connects to . What is the problem? How would you go about resolving this error?
  43. I have my backup RMAN script called “backup_rman.sh”. I am on the target database. My catalog username/password is rman/rman. My catalog db is called rman. How would you run this shell script from the O/S such that it would run as a background process?
  44. Explain the concept of the DUAL table.
  45. What are the ways tablespaces can be managed and how do they differ?
  46. From the database level, how can you tell under which time zone a database is operating?
  47. What’s the benefit of “dbms_stats” over “analyze”?
  48. Typically, where is the conventional directory structure chosen for Oracle binaries to reside?
  49. You have found corruption in a tablespace that contains static tables that are part of a database that is in NOARCHIVE log mode. How would you restore the tablespace without losing new data in the other tablespaces?
  50. How do you recover a datafile that has not been physically been backed up since its creation and has been deleted. Provide syntax example.

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