This tutorial explains the basics of the until loop in Bash. The until loop is used to execute a given set of commands as long as the given condition evaluates to false.
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
In this tutorial, we will cover the basics of for loops in Bash. We will also show you how to use the break and continue statements to alter the flow of a loop.
Loops are one of the fundamental concepts of programming languages. This tutorial covers the basics of while loops in Bash.
Learn to use if-else statements, for loops, and while loops to build complex conditional programs in R, a valuable skill for aspiring data scientists.
For loop in C++ Program | C++ For Loop Example.
In this tutorial, we will cover the basics of the select construct in Bash. The select construct generates a menu from a list of items. It has almost the same syntax as for loop.If the user enters a number that corresponds to the number of one of the displayed items, then the value of [ITEM] is set to that item. The value of the selected item is stored in the variable REPLY. Otherwise, if the user input is empty, the prompt and the menu list are displayed again.