SEARCH KEYWORD -- Class


  Shell script common interview questions

Shell script is frequently used when monitoring system status on Linux. It's not an easy task to write shell script but it's a very important skill for developers and system administrators to ease work and automate common tasks. This post will share some common interview questions about shell script. 1. Get random characters(8 characters) Method 1 # echo $RANDOM |md5sum |cut -c 1-8 471b94f2 Method 2 # openssl rand -base64 4 vg3BEg== Method 3 # cat /proc/sys/kernel/random/uuid |cut -c 1-8 ed...

   LINUX,INTERVIEW,SHELL SCRIPT     2018-09-28 10:46:00

  How small should a function be?

"The well-designed functions are often relatively small, large function design is often a mess or there is a lot of room for optimization."Maybe you think there is no need to discuss the size of functions, because the nature of the function design is cohesive, its size is only its manifestations. But it is necessary to discuss about the size of function because the statement above .First let's understand the concept of minimum code processing unit : a basic operation (assignment, comparison, etc...

   Function size,Optimization     2012-12-18 13:58:07

  JavaScript to open link in new window without being popup blocked

To ensure security and reduce spamming, modern browsers have implemented very strict rules on when a new window can be opened in a web page. Currently browsers restrict that any new web page to be opened in a new window must be initiated with an user action. The action is usually an user click event. Otherwise, a popup blocker would show on the browser address bar which indicates that something is blocked. To workaround this issue, normally you should implement the window open logic in a click e...

   JAVASCRIPT,IFRAME,NEW WINDOW,OPEN LINK     2018-09-22 04:29:30

  The hidden risk of passing slice as function parameter

In Go's source code or other open source libraries, there are lots of cases where a slice pointer is passed to function instead of slice itself. This brings up a doubt why not passing slice directly as its internal is backed by an array pointer to point to underlying data? For example, in log package, the formatHeader function takes a parameter buf as type *[]byte instead of []byte. func (l *Logger) formatHeader(buf *[]byte, t time.Time, file string, line int) {} Let's understand the r...

   GOLANG,SLICE,SLICE POINTER     2020-12-13 06:11:14

  Java Cipher encryption/decryption example

In Java, Cipher is the API for doing data encryption/decryption. Many cryptographic algorithms such as AES, DES, RC4 etc can be specified when creating Cipher instance. The Cipher instance calls the underlying algorithm specific implementation to do the actual encryption/decryption.  Before doing the encryption/decryption, a key needs to be created and it will be used to do the encryption/decryption. A sample program for performing all these is : import java.security.Key; import javax.cryp...

   Java, Java Security, Cipher, Example, Sample     2015-08-14 07:07:10

  A guide on installing and running Clickhouse on macOS

ClickHouse is a high-performance open-source columnar database management system developed by Yandex. Here are some of the key features of ClickHouse: Columnar storage: ClickHouse uses a columnar storage format, which allows it to efficiently store and retrieve data by column, rather than by row. This results in much faster query performance, especially for analytical and aggregate queries. Real-time data processing: ClickHouse is designed to handle real-time data processing and can handle bill...

   CLICKHOUSE,MACOS     2023-02-15 06:04:55

  Undefined property or variable in JavaScript

JavaScript is a weak type language, and also you can use a variable or property where it's undefined. If we don't have correct ways to check whether a property or variable is defined, we may get unexpected results when we try to access the,. How can we check whether a property or variable is undefined? This is actually a somewhat tricky question. Let's start off with some facts about undefined and then see what kind of function is consistent with the ones we care about. JavaScript attaches type...

   Property,Undefined,Array,JavaScript     2014-07-24 06:56:07

  CASSANDRA data model

Cassandra is an open source distributed database, it combines dynamic key/value and column oriented feature of Bigtable. Features of Cassandra are: Flexible schema, no need to design schema first, it's very convenient to add or delete strings Support range search on keys High usability, extensible. The single node error will not affect the cluster. We can think Cassandra's data model as a 4 or 5 dimensional Hash. COLUMN Columns is the smallest data unit in Cassandra, it is a 3 dimensional data...

   Cassandra,database,sort     2013-06-08 22:07:40

  Microsoft Edge extension manifest v2 migration to v3

In June 2023, Microsoft Edge would not allow Edge extensions with manifest version before v3 to be listed on Microsoft web stores as v3 extensions add more security privacy related restrictions on some of the functions. Hence all extensions with manifest v2 must migrate to v3. In this post, we would show how we did the migration for one of our extensions and the changes made. There is a checklist provided by Microsoft Edge team on what needs to be updated so that the extension can stil...

   MICROSOFT EDGE,EXTENSION,MANIFEST V3     2022-10-01 02:54:47

  Deep clone of JavaScript object

In JavaScript world, it's frequently seen object clone. Normally when creating a clone of an object, it's only the reference being cloned but not all contents. In some scenarioes, it's desired to clone all the content instead of just the reference such that any change made to the cloned object will not change the original object. Differences between shallow clone and deep clone can be as simple as: Shallow clone : Only the object reference is cloned but not the content Deep clone : Clone all co...

   JAAVSCRIPT,DEEP CLONE,DEEP COPY,SHALLOW CLONE,SHALLOW COPY     2016-10-31 00:27:24

RECENT