operating system questions and answers

pipeline to achieve this need.[email protected] ~]# Cat File_name.txt | More8. Q: Which user does the data dictionary belong to?A: The data dictionary belongs to the ' sys ' user, and the user ' sys ' and ' Sysem ' are automatically created by default by the system.9. Q: How do I view a summary and usage of a Linux command?Suppose you accidentally see a command in the/bin directory that you've never seen before, how do you know how it works and how i

load Java extension libraries. The implementation of the Java virtual machine provides an extension library directory. The class loader finds and loads Java classes in this directory.3. Systems Class Loader (System class loader): It loads Java classes based on the Java application's Classpath (CLASSPATH). In general, Java-applied classes are loaded by it. It can be obtained by Classloader.getsystemclassloader ().4. User-defined ClassLoader, implement

amount of the month, Debitoccur: The amount of the occurrence.Database name: Jcyaudit, Data set: Select * from TestDBAnswer: Select A.*From TestDB A, (select Occmonth,max (debitoccur) debit101ccur from TestDB where accid= ' 101 ' GROUP by Occmonth) bwhere A.occmonth=b.occmonth and A.debitoccur>b.debit101ccur************************************************************************************Interview question: How to put such a tableYear Month amount1991 1 1.11991 2 1.21991 3 1.31991 4 1.41992 1

NULL5 8 NULLNULL NULL 9------------------------------------------1)Select a. department name Dname,b. Performance YJ as ' January ', c. Performance YJ as ' February ', d. performance YJ as ' March 'From table1 a,table2 b,table2 c,table2 DWhere a. DEP Department = B. DEP department and b. Month Mon = ' January ' andA. Department dep = c. DEP department and c. Month Mon = ' February ' andA. Department dep = D. Department DEP and d. Month Mon = ' March ' and2)Select A.DEP,SUM (case if B.mon=1 then

First step: Find all files in the/oldboy directory and its subdirectories that end with the extension. shFind all Files:[Email protected] oldboy]# find/oldboy/-type f/oldboy/t.sh/oldboy/test.sh/oldboy/test/del.sh/oldboy/alex.txt/ Oldboy/oldboy.txtFind all files ending with. sh[Email protected] oldboy]# find/oldboy/-type f-name "*.sh"/oldboy/t.sh/oldboy/test.sh/oldboy/test/del.sh13.2 Step Two: How to replace the Oldboy in a file with the Oldgirl[[email protected] oldboy]# #sed ' s# What you're l

is used for medium-sized and large-scale data applications. The serial collector is sufficient for most small applications, which require about 100M of memory on modern processors.41. In Java, when can objects be garbage collected?This object can be recycled when the object becomes inaccessible to applications that currently use the object.Is there a garbage collection in the permanent generation of 42.JVM?Garbage collection does not occur in a permanent generation, and if it is permanently ful

+ SendSynchronousRequest:returningResponse:error: is synchronous access to data, that is, the current thread is blocked, and waits for the request to return the response, while –initwithrequest:delegate: using an asynchronous load, when it finishes network access, it passes delegate back to the main thread, and its delegate object.55. What is multithreading?Multithreading is a complex concept, in the literal sense is to complete a number of tasks synchronously, improve the use of resources effi

Multithreading and concurrency issues are one of the questions that interviewers prefer to ask in a Java technology interview. Here, the most important questions are listed from the interview point of view, but you should still have a solid grasp of Java multithreading Basics to meet the future problems. (Proofing Note: Very much agree with this view) Java Multithreading interview question 1. What is the di

Interview questions about the Linux firewall ' iptables 'Nishita Agarwal, a tecmint user, will share an interview experience with a company she has just experienced (Pune, a private company in India). She was asked many different questions during the interview, but she was an expert on iptables, so she wanted to share these questions about iptables and the

Core Java Questions and Answers (1-33), answers1-33Preface Http://www.journaldev.com/2366/core-java-interview-questions-and-answers.What are the important features of Java 8? Java 8 was released in March 2014, which is very common in Java interviews. If you can answer this question clearly, you are not out and would like to learn the latest technologies. Java 8 i

Multithreading and concurrency issues are among the questions that interviewers prefer to ask in a Java technology interview. Here, the most important questions are listed from the interview point of view, but you should still have a solid grasp of the basics of Java multithreading to match the problems you encounter later. ( proof Note: Very much agree with this view )Java Multithreading interview question

 original link Connection author : Pankaj translator : Zheng Xudong proofreading : Fang FeiMultithreading and concurrency issues are among the questions that interviewers prefer to ask in a Java technology interview. Here, the most important questions are listed from the interview point of view, but you should still have a solid grasp of the basics of Java multithreading to match the problems you encount