While Loop Linux Example

If you want the while loop to stop after some condition, and your foo command returns non-zero when this condition is met then you can get the loop to break like this. while foo do echo 'sleeping' sleep 5 done For example, if the foo command is deleting things in batches, and it returns 1 when there is nothing left to delete.. This works well if you have a custom script that needs to

This example shows how to use a C-style while loop in bash. As its name suggests, the C-style while loop basically follows the structure of the C programming language . The double parentheses contain the condition in this style loop just like in the C programming language.

This example demonstrates a simple for loop in Bash, iterating over a list of colors stored in the COLORS variable. The loop prints a message for each color, indicating the current color being processed. The loop iterates until all color values are exhausted. 2. Creating an Infinite Loop with quotwhile truequot in Shell Script

The bash while loop is a control flow statement that allows code or commands to be executed repeatedly based on a given condition. For example, run echo command 5 times or read text file line by line or evaluate the options passed on the command line for a script.

Basic while loop syntax in Bash. The syntax of while loop would vary based on the programming language you choose such as C, perl, python, go etc. The provided syntax can be used only with bash and shell scripts. while CONDITION do CONSEQUENT-COMMANDS done . Understanding the syntax. The CONDITION can be any type of condition such as using comparison operators, adding command check etc.

In this example, we can see that the while loop has a condition with non-bash operators like -le, -ge, etc instead we use the C-styled operators in the condition. The rest of the loop is the basic loop as in BASH, the variable or iterator i is incremented by two as we can see in the last statement of the loop body.

The while loop syntax. The syntax is while condition do command1 command2 .. . commandN done Command1..commandN will execute while a condition is true. To read a text file line-by-line, use the following syntax

The while loop in a Linux Bash script is a type of loop that continues to execute as long as the programmed condition remains true. while loops are useful when you need to repeatedly execute a set of instructions a certain number of times, or when you want to create an infinite loop. In this tutorial, you will see various examples of while loops in a Bash script so you can learn how they are

break and continue Statements . The break and continue statements can be used to control the while loop execution.. break Statement . The break statement terminates the current loop and passes program control to the command that follows the terminated loop. It is usually used to terminate the loop when a certain condition is met. In the following example, the execution of the loop will be

Example while -f quotpathtofilequot This loop will continue as long as the file quotpathtofilequot exists and is a regular file. Command Execution You can also use the output of a command as the condition for a quotwhilequot loop. Example while grep -q quotpatternquot file.txt. This loop will continue as long as the grep command finds the specified