Tutorials

This article will cover steps to find used ports (on destination side) by an app on Android using adb command. We will use pixel-2 for read more

This article will cover steps to install Android 8 on Pixel 2. The similar steps can also be used to install other Android versions in read more

This article will cover steps to find top processes by memory/cpu on Android using Adb. We will use pixel-2 for this article. But any other read more

Steps to root an Android Pixel 2 phone using Magisk and boot.img patching. Unlock bootloader Enable debug mode in Android if not done already Reboot read more

Sample usage to remove string prefix and extract remaining number in suffix.  The outcome will be

One can use iptables to forward a specific port to another port using NAT PREROUTING chain. This can be used to make a server available read more

Google camera can be installed on Asus m1 max pro after enabling camera2api. The below steps are assuming you have a Mac machine with adb read more

The below steps are assuming you have a Mac machine with adb and fastboot tools and developer option and usb debugging is enabled on your read more

The below steps are assuming you have a Mac machine with adb and fastboot tools installed and developer option and usb debugging is enabled on read more

Command lscpu to find number of cpus on linux $ lscpu lscpu Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Byte Order: Little Endian CPU(s): 32 On-line read more

System ui tuner can be enable to Android Marshmallow, Nougat or Orio. It lets us customize more system ui settings on Android e.g. status bar read more

Iterate Python dictionary (associative arrays) Using keys It is not memory efficient for large dictionaries. Using values It is not memory efficient for large dictionaries. read more

To show top 5 processes by cpu $ adb shell top -m 5 -s cpu Sample outcome User 16%, System 3%, IOW 0%, IRQ 0% read more

Allowing theme editing from web can be prone to spam. To disable theme and plugin editor, add the following to wp-config.php define( ‘DISALLOW_FILE_EDIT’, true ); read more

Steps to enable WebGL on old MAcbook (e.g. later 2011) Visit chrome://settings and make sure under advanced settings > System > Use hardware available when read more

Command to find slave lag (on mysql slave): $ mysql -u root –password=PASSWORD -e “show slave status\G” | grep Seconds_Behind_Master Seconds_Behind_Master: 0

Create a detached head situation $ git branch * master $ git log –oneline 55fff69 v3 1fd2aa6 file1 $ git checkout 1fd2aa6 Note: checking out read more

Git – rename local branch $ git branch -m oldname newname

Display HEAD pointer $ cat .git/HEAD ref: refs/heads/foo1 Display HEAD pointer (detached head case) $ cat .git/HEAD 1fd2aa6a8ff7205c91fde3d9557c6d67eeaf4eb1

Display last commit info from head in one line $ git log –pretty=format:”%h|%an|%ad|%s” -1 97d79ec|Dave Methvin|Mon Nov 9 17:49:01 2015 -0500|Dimensions: Empty sets should return read more

Display last commit from head to with specific commit hash length $ git log –pretty=format:”%h” –abbrev=7 -1 97d79ec

Use git show and check for exit status $ git show -s 97d79ecf6b6 commit 97d79ecf6b6c5cc3c1485eb3c46e12986a978f57 Author: Dave Methvin Date: Mon Nov 9 17:49:01 2015 -0500 read more

show a commit details (without file diff) $ git show -s 97d79ecf6b6 commit 97d79ecf6b6c5cc3c1485eb3c46e12986a978f57 Author: Dave Methvin Date: Mon Nov 9 17:49:01 2015 -0500 Dimensions: read more

git log with name $ git log –name-status … git log with name (one entry) $ git log –name-status -1 commit fbf829b7245f7d76ea02a44ab0a62427214b7575 Author: Timmy Willison read more

Print a number/float in php to two decimal places:

Find elapsed time in php using microtime.

Delete local branch $ git branch -d BRANCHNAME ## list branches $ git branch

Create branch without switching $ git branch NEWBRANCHNAME ## list branches $ git branch Create branch and switch to it $ git checkout -b NEWBRANCHNAME read more

When using linux find, -iname can be used to match name pattern and ignore case (case insensitive). $ fine . -iname “pattern” Example Find all read more

To exclude directory or file pattern when using find on command line one can use ! -name “pattern_to_exclude” Example To exclude a directory using its read more

Mac command line utility chflags can be used t unhide or hide a hidden folder or file on Mac. A hidden folder will start appearing read more

jQuery .append() can be used to add text to an div. The text can contains tags inside it.

jQuery slideDown, slideUp, slideToggle can be used to display, hide or toggle and element in sliding motion. .slideDown( [duration ] [, complete_callback ] ) .slideDown( read more

Javascript object.select() can bse used to select full text in textarea and text put fields in HTML. Example – select all in textarea Example – read more

CSS bottom property decides the bottom offset (bottom edge of element offset from bottom edge of container) for positioned elements. An element is considered positioned read more

CSS right property decides the right offset (right edge of element offset from right edge of container) for positioned elements. An element is considered positioned read more

CSS top property decides the top offset for positioned elements. An element is considered positioned if its position property has value other than static. Few read more

CSS left property decides the left offset for positioned elements. An element is considered positioned if its position property has value other than static. Few read more

To place a div in bottom right corner of browser or iframe, we can use position:fixed along with right and bottom property value assigned to read more

Javascript can declare anonymous function and call it at the same time using the following syntax: (function (arg1, arg2, …) { }) (arg1, arg2, …); read more

Mysql contains size of all tables in information_schema.TABLES table. The following query can be used to get size of all databases on a mysql server: read more

To display keys added to ssh-agent using ssh-add, run the following commands. Lists fingerprints of all identities currently represented by the agent $ ssh-add -l read more

Mysql SHOW TABLE STATUS command can be used to display information about all or specified tables in mysql db. Here are some examples: Show status read more

Css round toggle switch can be implemented using html checkbox and a label tag which appears after it. The high level approach steps are: We read more

HTML input tag with type=checkbox can be used to create check box in html. It can also be nested in label tag. When inside label read more

Ruby gem is a package manager for the Ruby programming language. Here are some gem handy commands on Mac or Linux. Install a package $ read more

Sass can be installed on Mac or Linux using ruby gem. To install sass follow these steps. Install sass gem $ sudo gem install sass read more

Netcat (nc) can be use as a mini server which can listen to either tcp or udp port on Mac or Linux. nc – listen read more

CSS transform:scale(2, 2) can be used on hover to resize (double) an image (horozontally and vertically). We can use any scale factor. Here is an read more

The background-image property sets the background image of an element.

The background-color property sets the background color of an element. The color is drawn behind any background images. Example – background-color

Here are some handy wget commands wget with username and password In case a url requires simple web auth, one can use the following wget read more

CSS flexbox can be used to align a div in center of container div both vertically and horizontally. Use the flexbox with following properties: justify-content: read more

jQuery can be used to handle these events on an input text field. change (when text input field changes and loses focus) $(‘input#field1’).on(‘change’, function(evt) { read more

CSS property display can be used to define flex box container. It can have two values: display: flex; display: inline-flex; Syntax: Example – display:flex and read more

CSS flex is the shorthand property for flex-grow, flex-shrink and flex-basis. flex-shrink and flex-basis are optional. Its default value is 1 0 auto. Syntax: Example read more

CSS flex-basis define the initial base size of the flex-item. Note that the final size of flex-item will depend upon flex-grow and flex-shrink values. Syntax: read more

CSS align-self property can be used to override align-items value (defined at flexbox level) for a specific flex-item. Syntax: Example – align-self This example uses read more

CSS flex-shrink property lets a flex item to shrink if needed. Its initial value is 1. That mean by default flex items will shrink. It read more

CSS flex-grow property lets a flex item to grow if needed. Its initial value is 0. That mean by default flex item does not grow. read more

Flex items are, by default, displayed in the same order as they appear in the source document. The order property can be used to change read more

The align-content property aligns a flex container’s lines within the flex container when there is extra space in the cross-axis. This property has no effect read more

The align-items property can be used to align flex items in vertical diretion. It is flex container property. Syntax: align-items values flex-start flex-end center baseline read more

The justify-content property aligns flex items along the main axis of the current line of the flex container. It is flex container property. Syntax: justify-content read more

The flex-flow property is a shorthand for setting the flex-direction and flex-wrap properties. It is flex container property. The default value is row nowrap. Syntax: read more

The flex-wrap property controls whether the flex container is single-line or multi-line. It is flex container property. Syntax: Example – flex-wrap

The contents of a flex container can be laid out in any direction and in any order using flex-direction. It is flex container property. Syntax: read more

The Number JavaScript object is a wrapper object allowing you to work with numerical values. A Number object is created using the Number() constructor. It read more

The parseInt() function parses a string argument and returns an integer of the specified radix (default 10). In case the string starts with a valid read more

The isNaN() function determines whether a value is NaN (Not-A-Number) or not. Note that parseInt approach may not work with strings having valid number prefix. read more

jQuery ui can be used to create a slider with updated value getting displayed in an input text box and any update in text box read more

jQuery ui can be used to create a slider with updated value also getting displayed. Syntax: Example – slider and input text box – one read more

CSS (CSS3) box-shadow property attaches one or more drop-shadows to the box. CSS property box-shadow Few points to note: blur radius spread distance and color read more

CSS3 text-shadow accepts a comma-separated list of shadow effects to be applied to the text of the element. CSS property text-shadow blur-radius and color are read more

A gradient is an image that smoothly fades from one color to another. These are commonly used for subtle shading in background images, buttons, and read more

In case you have accepted to get notifications from a site, it can be disabled later. These are the steps Click on Chrome settings from read more

Systemd is an init system used by new Linux distributions like Ubuntu 15 and Centos 7. It intends to replace Sysv init (Ubuntu, Centos, etc) read more

Centos/RHEL Linux yum command line tool can be used to find which package a file belongs to. Fine packages based filename To find package which read more

AngularJS ng-list directive can be used in text input and it converts between a delimited string and an array of strings. The default delimiter is read more

Linux command iptables can be used to make changes to Linux iptables. By default these changes are not reboot-safe and will get lost on reboot. read more

Vagrant is an excellent tool to create and configure lightweight, reproducible, and portable development environments. Here is a quick start guide to use vagrant on read more

To show volume icon on Mac top menu bar follow these steps: Open system preferences by using spoltlight search. Click on sound icon Select sound read more

Linux iptables is a user-space application program that allows a system administrator to configure the tables provided by the Linux kernel firewall (implemented as different read more

Angular ng-if directive removes or recreates a portion of the DOM tree based on an expression (true or false). On the other hand ng-show (or read more

AngularJS directive ng-href can be used to use a template to create href. Directly using it in href can make the link broken before Angular read more

AngularJS directive ng-hide hides an element if the expression ng-hide evaluates to true. Under the hood it adds or removes class ng-hide to the element. read more

AngularJS ng-focus expression is evaluated when an element (window, input, select, textarea, a) gets focus.

AngularJS directive ng-disabled sets the disabled attribute on the element if the expression ng-disabled evaluates to true.

AngularJS ng-cloak directive is used to prevent the Angular html template from being briefly displayed by the browser in its raw (uncompiled) form while your read more

AngularJS directives ng-class-even and ng-class-odd work like ng-class except that when these are used with ng-repeat, these apply to even and odd rows.

AngularJS ng-class directive allows you to dynamically set CSS classes on an element using an expression. The expression can be of one of these three read more

AngularJS ng-checked sets the checked attribute on the element, if the expression inside ng-checked is true.

AngularJS ng-change expression is evaluated when the user changes the input.

AngularJS ng-blur expression is evaluated when an element (window, input, select, textarea, a) loses focus.

AngularJS ng-bind-template attribute take a template string and can contain multiple {{ }} expressions.

AngularJS ng-bind attribute tells Angular to replace the text content of the specified HTML element with the value of a given expression. It also updates read more

Example1 AngularJS ng-gblclick example to increment a variable on every double click. Example2 AngularJS ng-dblclick example to increment a variable on every double click. This read more

Example1 AngularJS ng-click example to increment a variable on every click. Example2 AngularJS ng-click example to increment a variable on every click. This time use read more

Steps to remove an accepted certificate (e.g. a self signed certificate) from Chrome browser. Click on Chrome settings. On settings page click on advanced settings read more

To exclude a specific file extension (say .class) we can use –exclude “*.class” (or –exclude=”*.class”). Note that it can be repeated multiple time. $ rsync read more

git log –author=pattern can be used to show log of all users matching a specific pattern. $ git log –author=Ram $ git log –author=”R.*m” // read more

To checkout remote branch and track it from its remote origin $ git fetch $ git branch -v -a ##List available remote branches $ git read more

Steps to load iptable rules automatically on Ubuntu Linux using package iptables-persistent. Install iptables-persistent $ sudo apt-get install iptables-persistent When asked during installation should it read more

To print Java (JVM) home path on command line the following command (jave_home) can be used as shown below: $ /usr/libexec/java_home /Library/Java/JavaVirtualMachines/jdk1.7.0_65.jdk/Contents/Home To display all read more

To remove passphrase from an existing key, we can use ssh-keygen with -p option. Here is an example which changes passphrase of private rsa key read more

To check if an ssh key has passphrase, one can look for the presence of ENCRYPTED string in the private key. Here is an example read more

Netcat (nc) can be use to check if a remote port is reachable and client can connect to it. The following commands were tried on read more

When using a bastion host (or Jumpbox) to connection to production server using ssh private keys, ssh agent forward can be used. The main advantage read more

Sometimes it is useful to find what ports a machine is listening to. Here are some use cases: Display listening ports $ netstat -l Display read more

Chrome developer tools has a pretty handy feature to copy any GET/POST request in network tab to cURL. This also copies all headers involved in read more

Mac desktop icons size can be increased or decreased using Desktop view options. There are steps: Click anywhere on blank Desktop area. Click on View read more

Python cloning an array (list) using slice operator.

CSS padding property specify the width of the padding area of a box. padding values padding property can be used to specify padding-top, padding-right, padding-bottom, read more

CSS margin property specify the width of the margin area of a box. margin values margin property can be used to specify margin-top, margin-right, margin-bottom, read more

Javascript code to remove first item from array using arr.shift() Remove first item from array

Javascript code to prepend an item at the beginning of array using arr.unshift() Prepend one value to array

Javascript code to remove last item from array using arr.pop() Append one value

Javascript code to append one or multiple values at the end of array Append one value Append multiple values

CSS font-family is a list of font family names from which first value is used if present otherwise next value and so on. Here is read more

The CSS font-size property sets the font size of an html element. Example – font-size

The CSS font-weight property selects the weight of the font. The keyword normal is synonymous with 400, and bold is synonymous with 700. Values from read more

The CSS font-variant property can be used to select small-caps variation within font family. In a small-caps font the lower case letters look similar to read more

The CSS font-style property selects between normal (sometimes referred to as “roman” or “upright”), italic and oblique faces within a font family. Example – font-style

The CSS font property is a shorthand property for setting font-style, font-variant, font-weight, font-size, line-height and font-family. font values Few points to note: First three read more

CSS property pointer-events can be used enable/disable (default is enabled) mouse events on an element. If pointer-events is none for an element, the click event read more

CSS property content is used with the ::before and ::after pseudo-elements to generate content in a document. Example – display url after a tag text read more

CSS property clip (clipped region) defines what portion of an element’s border box is visible. The clip property applies only to absolutely positioned (position=absolute, fixed) read more

We frequently need to test css, javascript and HTML in old IE (internet explorer) browsers on Windows. This can be done using IE11 developer tools read more

Linux du command can be used to find disk usage of files and directories. Here are some handy du commands on Ubuntu Linux (or any read more

A clearfix class is a way for an element to automatically clear left and right float on its child elements. This eliminates the need to read more

Javascript event handler mousedown and mousemove can be used to make an element draggable without using any other library. This can be made to work read more

Step to create swap partition on Ubuntu Linux. It should work on any other Linux also. Create storage file (say 4GB) using fallocate for swap read more

Sometimes we need a large file with any content on Linux. This may be needs for benchmarking and testing purpose. Here are some ways to read more

Rsync can be used to sync directories and files from one machine to another. Sometime we want to see the progress and transfer speed. For read more

To find the inode number of a file on Linux/Unix the following approaches can be used. Find inode using ls $ ls -i file1.txt 412882 read more

Sometimes we need to truncate (make it size 0) a large opened file by a running process (e.h. php error log, apache error logs, custom read more

HTML li tag can be used inside ul or ol tags. Its closing tag is optional and it makes html more readable and less verbose. read more

CSS box-sizing decides if specified width, height, etc. will apply to content area of an element or to whole element including padding and border. Example read more

Swap space is the area on a hard disk which is part of the Virtual Memory. Swap space temporarily holds memory pages that are inactive. read more

Angular ngAnimate can be used to create animation effect using animation aware directives. Usage: Example – animate with ng-class This example uses ng-class to toggle read more

To merge two (or more) lists (arrays) the operator plus (+) can be used. It will append items of 2nd list to first list and read more

Angular ng-if directive removes or recreates a portion of the DOM tree based on an expression (true or false). Usage: Example – ng-if without animation read more

The CSS transition-delay property defines when the transition will start. It delays the transition from when it is applied. Example – transition-delay

The CSS transition-timing-function property describes how the intermediate values used during a transition will be calculated. In order words it describes transition effects like ease, read more

The CSS transition-duration property defines the length of time that a transition takes. Example – transition-duration

The CSS transition-property property specifies the name of the CSS property to which the transition is applied. Example – transition-property

CSS property transition can be used to create animation effect when other specified properties change. This can only be applied on animatable properties. Few points read more

to get jQuery version info the variable jQuery.fn.jquery (or $.fn.jquery if $ is being used for jQuery object) can be used. Some examples. jQuery version read more

jQuery ui can be used to make an element draggable/movable by mouse drag. Note that it does not work with touch events. Syntax: // After read more

JSON.parse() can be used to parse a given json string into javascript value (array, string, etc.) Here are some examples Example – parse json containing read more

JSON.stringify() can be used to convert a given javascript value to json strng. Usage: JSON.stringify(value[, replacer[, space]]) Here are some examples Example – JSON.stringify() default read more

Python rstrip can be used to removed trailing whitespaces (spaces, newlines, tabs, etc.) from a string. It Usage newstring = s.rstrip([chars]) If chars string is read more

The ng-init directive allows you to evaluate an expression in the current scope. This can be used to initialize model values. Usage: Example Initialize date read more

Angularjs ng-style directive can be used to define inline style attribute which can define dynamic style values using variables. Usage: Note that expression evals to read more

Python string can be converted to int using int(strval). Note that it will throw ValueError for invalid string. Here is a quick example to convert read more

Python int (or any other data type like float) needs to be converted to string before we can do concatenation operation using plus (+). It read more

Python dictionary (associative arrays) – some basic operations. Initialize dictionary Check if a key exists access value for a key list length/size using len() len() read more

Python in-built function type() can be use to find type of any variable or value. Example – type() of string variable Example – type() of read more

To initialize a large list with same value (all items having same value), the following syntax can be used. a = [val] * num_items Example

Slicing a list (array) in python is very handy way to get a sub list of an array. Its syntax is ## slice from start read more

To remove an item from python list method pop([i]) can be used. Remove last item Remove first item Remove ith item

Appending or prepending a value to a list in Python. Append value Prepend value

Python list (or array) – some basic operations. Initialize list access ith item access last item list length/size using len() Note than len() can also read more

To check if a string is part of another string (case sensitive) we can use these approaches Using in operator Using string find() method ## read more

To convert a string to lowercase of uppercase following code can be used: s_lower = s.lower() s_upper = s.upper() string lowercase example string uppercase example

Mac spotlight search is one of the most frequently used tool on Mac. It searches various folders on Mac and shows results. Here are steps read more

HTML5 script async attribute can be used to load a script asynchronously. with async one can also use onload attribute to attach any javascript code read more

jQuery when applied on a css selector, returns a wrapper object which contains 0 or more javascript objects. To get the javascript object from it, read more

CSS property cursor specifies the type of mouse cursor to be displayed on the element. Example css cursor

CSS outline-width property specify the width of an element’s outline (2px, 2em, etc.). Example css outline-width

CSS outline-style property specify the line style of an element’s outline (solid, double, dashed, etc.). Example css outline-style

The outline-color property sets the color of the outline. Note that the outline-color value invert if not supported, then initial value of color is taken. read more

CSS outline property can be used to create outlines around visual objects such as buttons, active form fields, image maps, etc. It it different from read more

jQuery can be used to access checkbox value using jQuery.attr(“value”) and it checked state using jQuery.prop(“checked”). Note that we can not use jQuery.attr() for checked read more

jQuery code to access select element’s selected index, selected value and selected option node text.

When two selectors have same style, then one with higher specificity wins. In case they have same specificity, the one which come later, wins. Specificity read more

To go to previous working directory is Linux is a frequently occurring need. These are two ways to achieve it: Using dash (-) $ cd read more

The universal selector (*), matches the name of any element type. It matches any single element in the document tree. Some ways it can be read more

CSS :nth-last-of-type(an+b) pseudo class represent all sibling elements of same type whose sibling position is obtained by putting n=0,1,2,3… and so on counting from last. read more

CSS :nth-last-child(an+b) pseudo class represent all sibling elements whose sibling position is obtained by putting n=0,1,2,3… and so on from last. Note that sibling can read more

Css negation pseudo-class, :not(X) can be used on any simple selector. It will match element which are not selected by selector X. Example – css read more

Css :empty pseudo-class represents an element that has no children at all. Few cases <p></p> is considered empty <div>hello</div> is not considered empty Example – read more

Css :only-of-type pseudo class represents an element that has a parent element and whose parent element has no other element children of same type. Example read more

Css :only-child pseudo class represents an element that has a parent element and whose parent element has no other element children. Example – css :only-child read more

CSS :nth-of-type(an+b) pseudo class represent all sibling elements of same type whose sibling position (starting from 1) is obtained by putting n=0,1,2,3… and so on. read more

CSS :nth-child(an+b) pseudo class represent all sibling elements whose sibling position (starting from 1) is obtained by putting n=0,1,2,3… and so on. Note that sibling read more

The :root pseudo-class represents an element that is the root of the document. In case of HTML, it is html element. Example – css :root read more

The :checked pseudo-class represents elements (checkbox and radio) that are in an selected (checked) state. Example – css :checked checkbox element This example highlights span read more

The :enabled pseudo-class represents elements (input, textarea, button, etc.) that are in an enabled state. Such elements have a corresponding disabled state also. Similarly :disabled read more

The :lang pseudo-class can used to select elements based on language. Example – css :lang This example show french language content in different color.

The :target pseudo-class applies to an element which has id matching with fragment identifier (string after hash). e.g. in url http://example.com/html/top.html#section1 section1 is fragment/anchor identifier. read more

To add clock widget (analog or digital) on Android Lollipop, these steps can be followed. For Android other versions, instructions are slightly different. Touch an read more

The CSS id selector matches element having a specific id attribute This can be used to specify CSS style based on element id. Note that read more

The CSS class selector matches element having a specific class name as one of the classes in attribute class. This can be used to specify read more

ECMAScript 6 String.prototype.endsWith() method can be used to check if a string ends with a suffix. But it is not yet supported by all browsers. read more

ECMAScript 6 String.prototype.startsWith() method can be used to check if a string starts with something. But it is not yet supported by all browsers. Another read more

Python if else statements can be expressed on two ways Simple if-else statement if-elif-else statement with one or more occurrences of elif. if else example read more

jQuery code snippet to get class list of an element. We are using jQuery attr(“class”) to get the class list as string and then splitting read more

Sometimes we need to create inline iframe with content generate from jQuery/Javascript. This iframe will not have src attribute. One use case is to run read more

CSS attribute selector can be used to select DOM elements based on matching substring of attribute values. We can use attribute substring selectors in multiple read more