Skip to content
Fix Code Error

How to compare strings in Bash

March 13, 2021 by Code Error
Posted By: Anonymous

How do I compare a variable to a string (and do something if they match)?

Solution

Using variables in if statements

if [ "$x" = "valid" ]; then
  echo "x has the value 'valid'"
fi

If you want to do something when they don’t match, replace = with !=. You can read more about string operations and arithmetic operations in their respective documentation.

Why do we use quotes around $x?

You want the quotes around $x, because if it is empty, your Bash script encounters a syntax error as seen below:

if [ = "valid" ]; then

Non-standard use of == operator

Note that Bash allows == to be used for equality with [, but this is not standard.

Use either the first case wherein the quotes around $x are optional:

if [[ "$x" == "valid" ]]; then

or use the second case:

if [ "$x" = "valid" ]; then
Answered By: Anonymous

Related Articles

  • List of Timezone IDs for use with FindTimeZoneById() in C#?
  • PHP parse/syntax errors; and how to solve them
  • What are the undocumented features and limitations…
  • Removing double quotes from variables in batch file…
  • Jetpack Compose and Hilt Conflict
  • Does moment.js allow me to derive a timezone…
  • data.table vs dplyr: can one do something well the…
  • How to echo with different colors in the Windows…
  • Bash: Echoing a echo command with a variable in bash
  • First echo missing when using bash -c over SSH
  • Best way to replace multiple characters in a string?
  • error LNK2005: ✘✘✘ already defined in…
  • What does "Fatal error: Unexpectedly found nil while…
  • Gradle error: Execution failed for task…
  • How can I parse a CSV string with JavaScript, which…
  • Reference — What does this symbol mean in PHP?
  • useEffect Error: Minified React error #321 (GTM…
  • What's the difference between eval, exec, and compile?
  • Database development mistakes made by application developers
  • Reference - What does this regex mean?
  • eval command in Bash and its typical uses
  • Trying to embed newline in a variable in bash
  • Simple logical operators in Bash
  • Change the location of the ~ directory in a Windows…
  • Show scroll update when scrolling down page
  • Check number of arguments passed to a Bash script
  • Logging best practices
  • What is an optional value in Swift?
  • Difference between single and double quotes in Bash
  • Smart way to truncate long strings
  • Redirect stderr to stdout in C shell
  • Echo a blank (empty) line to the console from a…
  • How do I use shell variables in an awk script?
  • Getting the closest string match
  • What is a NullReferenceException, and how do I fix it?
  • The definitive guide to form-based website authentication
  • What are bitwise shift (bit-shift) operators and how…
  • What's a concise way to check that environment…
  • org.gradle.api.tasks.TaskExecutionException:…
  • Using if(isset($_POST['submit'])) to not display…
  • What is a plain English explanation of "Big O" notation?
  • Memcached vs. Redis?
  • Why does C++ code for testing the Collatz conjecture…
  • What is the difference between single-quoted and…
  • What does this symbol mean in JavaScript?
  • What does "dereferencing" a pointer mean?
  • YAML: Do I need quotes for strings in YAML?
  • How to tell if a string is not defined in a Bash…
  • "Notice: Undefined variable", "Notice: Undefined…
  • How to run a shell script on a Unix console or Mac terminal?
  • How to generate a random string of a fixed length in Go?
  • What does a "Cannot find symbol" or "Cannot resolve…
  • shell script. how to extract string using regular…
  • How do I parse command line arguments in Bash?
  • When to use single quotes, double quotes, and…
  • Batch File: ( was unexpected at this time
  • How to Replace Multiple Characters in SQL?
  • Generating a drop down list of timezones with PHP
  • Why does this Azure Resource Manager Template fail…
  • How to filter a RecyclerView with a SearchView
  • What is the scope of variables in JavaScript?
  • What is your most productive shortcut with Vim?
  • How can I fix MySQL error #1064?
  • How to debug a bash script?
  • Accessing last x characters of a string in Bash
  • Java Process with Input/Output Stream
  • How to use double or single brackets, parentheses,…
  • Pandas how to split vlaues of every column based on colon
  • Shell Script Syntax Error: Unexpected End of File
  • What are type hints in Python 3.5?
  • How do I use the nohup command without getting nohup.out?
  • TypeError: Cannot read property 'webpackJsonp' of undefined
  • How to read specific characters from specific lines…
  • What's wrong with 'template int compare(char p1 [N],…
  • PHP for loop Show the entries in ascending order by quantity
  • Current time formatting with Javascript
  • How can I find the product GUID of an installed MSI setup?
  • Typeerror: n is undefined in underscore.min.js
  • How to get $HOME directory of different user in bash script?
  • Usage of __slots__?
  • Codeigniter 4 hasChanged() - I was expecting no…
  • What does "Could not find or load main class" mean?
  • Python subprocess with apostrophes, removes them
  • Exporting awk variables to bash variables?
  • Pass all variables from one shell script to another?
  • regex match any single character (one character only)
  • How does PHP 'foreach' actually work?
  • How to define hash tables in Bash?
  • Read a file line by line assigning the value to a variable
  • Git Using Remote Branch
  • How to check if a variable is set in Bash?
  • How do JavaScript closures work?
  • Design DFA accepting binary strings divisible by a…
  • MySQL database is not receiving any data in PHP
  • Where do I find the current C or C++ standard documents?
  • Returning value from called function in a shell script
  • How do I pass variables and data from PHP to JavaScript?
  • How do I execute multiple SQL Statements in Access'…
  • A variable modified inside a while loop is not remembered
  • Are PDO prepared statements sufficient to prevent…

Disclaimer: This content is shared under creative common license cc-by-sa 3.0. It is generated from StackExchange Website Network.

Post navigation

Previous Post:

How can I print variable and string on same line in Python?

Next Post:

What is the difference between an interface and abstract class?

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

.net ajax android angular arrays aurelia backbone.js bash c++ css dataframe ember-data ember.js excel git html ios java javascript jquery json laravel linux list mysql next.js node.js pandas php polymer polymer-1.0 python python-3.x r reactjs regex sql sql-server string svelte typescript vue-component vue.js vuejs2 vuetify.js

  • you shouldn’t need to use z-index
  • No column in target database, but getting “The schema update is terminating because data loss might occur”
  • Angular – expected call-signature: ‘changePassword’ to have a typedeftslint(typedef)
  • trying to implement NativeAdFactory imports deprecated method by default in flutter java project
  • What should I use to get an attribute out of my foreign table in Laravel?
© 2022 Fix Code Error