In this post, you’re going to learn where to use the PowerShell replace() method and PowerShell replace operator. The tutorial will cover the basics and even drive into some regular expressions.
.Replace is a .NET method and -replace is a PowerShell operator that uses regular expressions. In another word, the .Replace() method comes from the .NET String class whereas the -Replace operator is implemented using System.Text.RegularExpressions.Regex.Replace().
The -replace operator takes a regular expression (regex) replacement rule as input and replaces every match with the replacement string.
When and where to use it?
Like other languages, PowerShell can work with strings and text. One of those useful features is to use PowerShell to replace characters, strings, or even text inside of files. In PowerShell, Replace() method and -replace operator is used to finding specified characters and replace them with a new string. To perform simple replacements, you can use the replace() method but if you need to match and replace anything more advanced, always use the replace operator.
.Replace Method:
Example 1: Replace characters in strings.
$string = ‘hello, dotnet-helpers.com’
In the above code, we gave the string that likes to replace. From the above string value, we would like to replace “hello” with “Welcome”. To do this in PowerShell, first you need to figure out the matched text. Once it’s found, need to replace that text with a user-defined value.
$string = ‘hello, dotnet-helpers.com’
$string.replace(‘hello’,’Welcome’)
The replace() method has two arguments; the string to find and the string to replace. As shown above, the “hello” string is going to replace with “Welcome”.
Points to Remember:
You can call the replace() method on any string to replace any literal string with another. If the string-to-be-replaced isn’t found, the replace() method returns nothing.
Example 2: Replacing multiple strings
You aware that replace() method returns a string, to replace another instance, you can append another replace() method at the end ( .replace(‘dotnet-helpers’,’dotnet-helpers.com!!!’) ). In the previous example, we try to replace “hello” with “Welcome”, in this example we trying to replace another string with one more .replace method as shown below.
$string = ‘hello, dotnet-helpers’
$string.replace(‘hello’,’welcome’).replace(‘dotnet-helpers’,’dotnet-helpers.com!!!’)
Points to Remember:
You can chain together as many replace() method calls as necessary
-Replace Operator:
The replace operator is similar to the .Replace method (in that you provide a string to find and replace). But, it has one big advantage; the ability to use regular expressions to find matching strings.
Example 1: Replacing single string
$string = ‘hello, dotnet-helpers.com’
$string -replace ‘hello,’, ‘Welcome to’
Example 2: Replacing multiple strings
Like the replace() method, you can also chain together usages of the replace operator.
$string = ‘hello, dotnet-helpers’
$string -replace ‘hello,’,’Welcome to’ -replace ‘dotnet-helpers’,’dotnet-helpers.com!!!’
-Replace Operator with Regex:
Replacing strings in PowerShell with the replace() method works but it’s limited. You are constrained to only using literal strings. You cannot use wildcards or regex. If you’re performing any kind of intermediate or advanced replacing, you should use the replace operator.
The -replace operator takes a regex (regular expression) replacement rule as input and replaces every match with the replacement string. The operator itself is used as shown in the following examples : <input string> -replace <replacement rule>,<replacement string>
Example 1: With Simple Regex
In this example, you can use the expression hello|hi to match both required strings using the regex “or” (|) character as you can see below. In the below regex, it finds the match for a string like “hello” or “hi” and if a match is found it will replace with the given string.
$string = ‘hi, dotnet-helpers.com’
$string -replace ‘hello|hi’,’Good day’
Example 2: Direct Replace of special character
As per the below example, you need to replace text in a string. That string contains a couple of regex special characters like a bracket and an exclamation mark. If you try to replace the string [dotnethelpers!] with dotnet-helpers.com as shown below, then it will not work as expected because the characters will have special meaning in regex language.
$string = “hi, [dotnethelpers!]”
$string -replace ‘[dotnethelpers!]’,’dotnet-helpers.com’
The problem is you often need to replace “[]”, “!” or other characters that have special meaning in regex language. One way to achieve this is to escape every special character by “\”.
To overcome this problem, you have two options. You can either escape these special characters by prepending a backslash to the front of each character or using the Escape() method (([regex]::Escape(‘[dotnethelpers]’)).
Points to Remember:
If you try to replace any special characters directly from the string using Replace operator then it won’t work correctly as characters will have special meaning in regex language.
Conclusion :
Replacing characters or words in a string with PowerShell is easily done using either the replace method or -replace operator. When working with special characters, like [ ], \ or $ symbols, it’s often easier to use the replace() method than the operator variant. Because this way you don’t need to escape the special character.
To perform simple replacements, you can use the replace() method but if you need to match and replace anything more advanced, always use the replace operator.