Bash if operators

Linda U. Anderson

Jul 2, 2025

2 min read

#Code to execute if either condition1 or .Comparison operators are operators that compare values and return true or false.Bash (see conditional expressions) seems to preempt the classic and POSIX meanings for -a and -o with its own alternative operators that take arguments.else and nested if so we will cover all such possible scenarios in this tutorial guide.

Bash if else usage guide for absolute beginners

$ chmod +x trymod4.In Bash scripting, ‘if’ is a versatile conditional statement that contains many options (conditional operators) to perform a specific task.smith: according to the Bash FAQ, [[was added to Bash in v2. Boolean evaluation in bash is actually used mainly for .

How to Compare Strings in Bash

The provided Bash script sets two example values, value1 and value2, to 10 and 20, respectively.It then employs an if statement to check two conditions.Balises :Bash If StatementShell ScriptingBash Programming+2If-Else in BashLinux Bash If Else SyntaxBasic Operators in Shell Scripting by DrRoot_, Geeks for Geeks is licensed under CC BY-SA 4. For example: if [ condition1 -a condition2 ]; then # Code to execute if both conditions are true fi Conclusion.In addition, to compare numbers in bash, there are numerous comparison operators like greater than or equal (>=), less than (<), greater than (-gt), not equal to (!=), equal to (-eq), and more that should be used inside the square brackets or parenthesis of the if statement. Test operators in bash scripts help you evaluate the conditions such as you may want to execute a specific block of code based . To fix this, always ensure you use the correct operators in your conditions.

Bash tests can be listed by running the “help test” command. In your particular case, you are using:-n string is not null. Use the == operator with the [[ command for .02 (1998), based on the ksh feature available since the 1980s. I will try to be as descriptive as possible from my side so that even an absolute beginner can .Balises :Bash If StatementShell ScriptingBash Programming+2Bash and Or OperatorBash Null True Or FalseBitwise Operators in Bash Scripting; An Overview of Bash Comparison [Conditional] Operators << Go Back to Bash Operator | Bash Scripting Tutorial. Syntax of if Statements. Inside (( )), there is no need for a $ behind variable names to expand them. I am trying to validate the input parameters passed to a shell script for no parameter and the first parameter passed is valid or not.This chain of operators only behaves like a ternary operator if you are positive that the command after && won't have a non-zero exit status. Example of each syntax is given below: If statement without any brackets: These are used to check the outcome of a command. So, Bash’s bitwise operators work only on signed integers, whose binary representation is in two’s . ksh, dash are used a lot but are not fully bash compatible. One of the key features of Bash scripts is the ability to create conditions and control the flow of execution using logical operators. Bash incorporates three primary logical operators for utilization in .

Compound 'if' statements with multiple expressions in Bash

The not equal operator generally used with the if or elif statements to check not equal and execute some commands.How can I use logical operators (AND, OR) in Bash if statements?

Bash scripting cheatsheet

This can be further enhanced to use if.bash 223 223 is NOT evenly divisible by 4 I put this in, because you used the single [ . Another major part of the Bash if statement machinations is the Logical Operator. Openwrt shell is ash which misses many bash characteristics.com is licensed under CC BY-SA 4. Expressions may be combined using the following operators, listed in decreasing order of precedence: ( expression) Returns the value of expression. If the TEST-COMMAND evaluates to True, the STATEMENTS1 will be executed.

Performing Math Operations in Bash [12+ Commands Explained]

In bash the two are equivalent, and in sh = is the only one that will work.List of test operators in bash . As detailed in stdint.Bash tests are a set of operators that you can use in your conditional statements in order to compare values together. Mohammad Shah Miran . So to make your expression work, changing && for -a will do the trick. The if statement will execute a set of statements if the condition is true .BASH – If statement and comparison operators.Learn how to use if statements in Bash scripts to make decisions based on conditions and perform actions. When comparing strings in Bash you can use the following operators: string1 = string2 and string1 == string2 - The equality operator returns true if the operands are equal.

At times you need to specify different courses of action to be taken in a shell script, depending on the success or failure of a command.

How to Use Bash If Statements (With 4 Examples)

Using If Else in Bash Scripts [Examples]

In 2012, when cdarke wrote that comment, it was already reasonable to say that it was in Korn shell for over 20 years.Balises :Bash If StatementBash Operator Sorted by: 208. Linux bash not equal operator is expressed with the “-ne” which is the .Balises :Bash If StatementBash Conditional ExpressionsLinux If Bash+2Bash If TestLinux If Statement

Utiliser if, then en Bash Linux

No need to quote variable expansions inside [[ ]] or (( )) - Bash doesn't do word splitting or globbing in these contexts.3 Lists of Commands. by sanaswati on 03/07/2012 in bash shell scripting.Balises :Bash If StatementCondition in BashBash If Command My use of the word modern in 2012 was certainly questionable; today, it would be . Bash scripts give us two .bash 224 224 is evenly divisible by 4 $ .Like other programming languages, Bash scripting also supports if. Using POSIX = is preferred for compatibility. It return the exist status of .Simple logical operators in Bash20 juil. These operators enable you to amalgamate multiple conditions, enabling you to make decisions based on the truth or falseness of these combined conditions. The following script will prompt you to enter three numbers and print the largest number among the three numbers. A list is a sequence of one or more pipelines separated by one of the operators ‘;’, ‘&’, ‘&&’, or ‘||’, and .Bash, or the Bourne-Again SHell, is a powerful and versatile scripting language widely used in the Linux and Unix environments.else statement takes the following form: if TEST-COMMAND. It is correct like this: if [ -f $VAR1 ] && [ -f $VAR2 ] && [ -f $VAR3 ] then .Learn how to use various Bash operators to test conditions, arithmetic functions, string comparison, file testing, and more in a Bash script.Bash OR Logical Operator. In this article, we’ll take a deep dive into the world of 2018What do the -n and -a options do in a bash if statement? Afficher plus de résultatsBalises :Bash If StatementBash and Or OperatorBash If N+2Bash If Condition in OperatorBash If Condition and Operator The case For if. With some care, you can use the more modern [[ operator, but be aware that the versions in Bash and Korn Shell (for example) need not be identical. See examples of .0 How to program with Bash: Logical operators and shell expansions by David Both, OpenSource.In order to execute a Bash “if else” statement, you have to use four different keywords : if, then, else and fi : if : represents the condition that you want to check; then : if the previous condition is true, .The Bash shell is primarily designed for performing arithmetic operations with whole numbers, both positive and negative, such as 1, -5, and 10. This may be used to override the normal precedence of operators. echo -n Enter the first number: read VAR1.You can place multiple if statements inside another if statement.Balises :Shell ScriptingLinuxBash Operators ListCondition in Bash

How to use IF ELSE statements in Shell Scripts

See the syntax, examples, and operators of if statements, such as !, .You can find a very nice reference for bash's operators here.

There are many arithmetic operators available in Bash such as addition, multiplication, subtraction, etc.Bash Logical Operators.Boolean evaluation in bash is short-circuit: true || false will never evaluate the false operand, because the true operand is enough to determine the outcome of the operation. Here, in the following section, I’m going to describe how you can avail the if statement with a single condition , multiple conditions , and nested if conditions to compare strings and integers. Otherwise, a && b || c will unexpectedly run c if a succeeds but b fails. ] conditional, which I usually associate with sh -compatible programs.

The if keyword .I was trying to combine logical AND & OR in a bash script within if condition. You can use if statements without any brackets or within [] or [ []] or ().

Bash Scripting and Conditional Logic: The Foundation.Balises :Bash If StatementBash If Condition in OperatorThe -a operator also doesn't work: if [ $STATUS -ne 200 ] -a [[ $STRING != $VALUE ]] For a more elaborate explanation: [and ] are not Bash reserved words.Bash has a large set of logical operators that can be used in conditional expressions.4 March 2022 by Korbin Brown. then STATEMENTS1. Compatibility is an issue for the programmer, to avoid learning a new shell specifics every time they move to another job. OR logical operator combines two or more simple or compound conditions and forms a compound condition.

Use the = operator with the test [ command.

Manquant :

Bash Scripting: Operators

You use it to check the state of a value, whether it is equal to another or not; .

‘If’ and ‘And’ Operators in Bash: Conditional Logic Guide

Variables · Functions · Interpolation · Brace expansions · Loops · Conditional execution · Command substitution · One-page guide to Bash scripting

Shell scripting:

If Statements

[[ ]] and (( )) can span multiple lines, without the need for a line continuation with \. Bash scripting is a powerful tool for automating tasks on Unix-like operating .To see the available tests, we can run man test and see all the comparison operators that can be used for integer comparison.Balises :Bash Operators ListLinuxCondition in BashBash Testif [[ $# -ne 1 || ! $1 =~ ^(ABC|DEF|GHI|JKL)$ ]]then  echo Usage: . ! expression

Bash If Statement: Syntax, Variations, Use Cases, Commands

Under Logical operators, Bash provides logical OR operator that performs boolean OR operation. Bash interprets this as trying to run two commands in parallel, leading to errors.0 How to program with Bash: Syntax and tools by David Both, OpenSource. Introduction to if.Balises :Shell ScriptingBash If CommandBash If TestLinux If Statementsh [ABC | DEF | GHI | JKL] >&2  exit 1fiSee more on stackoverflowCommentairesMerci !Dites-nous en davantageBalises :Shell ScriptingCondition in BashConditional Bash+2Bash If Condition and OperatorBash Combine ConditionsDans ce tutoriel, je vous explique comment utiliser les déclarations if, then en Bash Linux avec de nombreux exemples de syntaxes, utilisations et la liste des opérateurs.

syntax

Linux Bash scripting language provides the not equal “-ne” operator in order to compare two values if they are not equal. It’s the equivalent of == in other programming . These arithmetic operators facilitate arithmetic calculation.Bash performs all its arithmetic on intmax_t numbers with no checking for overflow.Balises :Bash If StatementLinuxOperators in Bash Scripting+2Korbin BrownBash and Conditional Statement

Bash If Else Syntax With Examples

Different Forms of Conditional Test.Software : Bash shell (installed by default)

Bash Scripting: Conditionals

-z string is null, that is, has zero length To illustrate:The elif Clause.) The arithmetic operators used for test conditions are:-eq is used to compare whether two integers are equal or not. 5/5 - (5 votes) LINUX FUNDAMENTALS A Complete Guide for Beginners Enroll Course Now . Bash boolean OR operator takes two operands and returns true if any of the operands is true, else it returns false.