This video gives you the true and profound understanding of while loops in bash. Watch Full Video for a better understanding and clear your core concepts.
Loops are one of the fundamental concepts of programming languages. Loops are handy when you want to run a series of commands over and over again until a certain condition is reached.
In scripting languages such as Bash, loops are useful for automating repetitive tasks.
In this tutorial, we will cover the basics of for loops in Bash. We will also show you how to use the
continue statements to alter the flow of a loop.
for loop iterates over a list of items and performs the given set of commands.
for loop takes the following form:
for item in [LIST] do [COMMANDS] done
The list can be a series of strings separated by spaces, a range of numbers, output of a command, an array, and so on.
In the example below, the loop will iterate over each item in the list of strings, and the variable
element will be set to the current item:
for element in Hydrogen Helium Lithium Beryllium do echo "Element: $element" done
#bash #loop #bash for loop
Loops are one of the fundamental concepts of programming languages. Loops are handy when you want to run a series of commands over and over again until a specific condition is met.
In scripting languages such as Bash, loops are useful for automating repetitive tasks. There are 3 basic loop constructs in Bash scripting,
[while](https://linuxize.com/post/bash-while-loop/) loop, and
This tutorial explains the basics of the
until loop in Bash.
until loop is used to execute a given set of commands as long as the given condition evaluates to false.
until loop takes the following form:
until [CONDITION] do [COMMANDS] done
The condition is evaluated before executing the commands. If the condition evaluates to false, commands are executed. Otherwise, if the condition evaluates to true the loop will be terminated and the program control will be passed to the command that follows.
In the example below, on each iteration the loop prints the current value of the variablecounterandincrements the variableby one.#!/bin/bash counter=0 until [ $counter -gt 5 ] do echo Counter: $counter ((counter++)) done
The loop iterates as long as the
counter variable has a value greater than four. The script will produce the following output:
Counter: 0 Counter: 1 Counter: 2 Counter: 3 Counter: 4 Counter: 5
#bash #loop #bash until loop
Using variables and loops we can write scripts that work on a large set of files without writing it all out by hand.
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When we’re programming in R (or any other language, for that matter), we often want to control when and how particular parts of our code are executed. We can do that using control structures like if-else statements, for loops, and while loops.
Control structures are blocks of code that determine how other sections of code are executed based on specified parameters. You can think of these as a bit like the instructions a parent might give a child before leaving the house:
“If I’m not home by 8pm, make yourself dinner.”
Control structures set a condition and tell R what to do when that condition is met or not met. And unlike some kids, R will always do what we tell it to! You can learn more about control structures in the R documentation if you would like.
In this tutorial, we assume you’re familiar with basic data structures, and arithmetic operations in R.
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In order to use control structures, we need to create statements that will turn out to be either
FALSE. In the kids example above, the statement “It’s 8pm. Are my parents home yet?” yields
TRUE (“Yes”) or
FALSE (“No”). In R, the most fundamental way to evaluate something as
FALSE is through comparison operators.
Below are six essential comparison operators for working with control structures in R:
==means equality. The statement
x == aframed as a question means “Does the value of
xequal the value of
!=means “not equal”. The statement
x == bmeans “Does the value of
xnot equal the value of
<means “less than”. The statement
x < cmeans “Is the value of
xless than the value of
<=means “less than or equal”. The statement
x <= dmeans “Is the value of
xless or equal to the value of
>means “greater than”. The statement
x >e means “Is the value of
xgreater than the value of
>=means “greater than or equal”. The statement
x >= fmeans “Is the value of
xgreater than or equal to the value of
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A Python tutorial to understand the uses of for loop in various ways including examples.
Python is a general-purpose programming language, which emphasizes making programming easy, efficient coding, and unleashes the user’s potential. Loops are the vital part of programming as it allows the user to repetitive use a set of codes using loops. So in the following article, we will see how to use
for loops in python.
Till the iteration of the last item in the sequence, for loop run the instructions. It iterates over sets of instructions in sequence, arrays, and a tuple for a pre-defined period or until the last item and calculation are executed.
For loop can be categorized in three ways.
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