How to Replace Part of a String Using Powershell

There are two very simple ways to replace text within a string in Powershell.

First, let’s look at using the replace function.

Using the replace() function

You can replace part of a string using the replace function:

$str = "Hello world!"

$str.replace("world", "Mars")Copy

Hello Mars!Copy

There are two things to note here:

• Parameters are case sensitive
• The function will replace every instance of the string it finds

For instance, if we attempt the same with a more repetitive string:

$str = "Hello, hello, hello world!"

$str.replace("hello", "ello")Copy

Hello, ello, ello world!Copy

Note that two out of three instances were replaced. The first instance of “hello” however, was capitalized, and therefore ignored (there’s a solution to this in the operator example below).

Using the -replace operator

Alternatively, we could use the -replace operator:

$str = "Hello world!"

$str -replace "world", "Earth"Copy

Hello Earth!Copy

Whilst this still changes every instance of the substring that it finds, this time the parameter is case insensitive:

$str = "Hello, hello, hello world!"

$str -replace "hello", "ello"Copy

ello, ello, ello world!Copy

Using RegEx

One of the advantages of using the operator over the function, is that you can supply regular expressions to the first parameter of the replace operator,

For instance, if we wanted to replace all instances of the words “world”, “earth”, and “mars”, we could either perform the replace three times, or simply use the OR RegEx operator: |

$str = "Hello world!"

$str -replace "world|earth|mars", "unspecified planetary body"Copy

Hello unspecified planetary body!Copy

Case-Insensitive Replace

As shown above, the -replace operator is case-insensitive by default. This makes it the easiest way to do a case-insensitive replace in PowerShell:

$str = "Hello HELLO hello"

$str -replace "hello", "hey"Copy

hey hey heyCopy

If you actually want case-sensitive behavior with the operator, use -creplace instead:

$str = "Hello HELLO hello"

$str -creplace "hello", "hey"Copy

Hello HELLO heyCopy

The .replace() function, on the other hand, is always case-sensitive. There’s no built-in flag to change that, so if you need a case-insensitive replace with the function, you’re better off just using -replace.

Replacing Characters in a String

The same techniques work for replacing individual characters in a string. Swap out a single character:

$str = "one-two-three"

$str -replace "-", " "Copy

one two threeCopy

Replace multiple different characters at once using a RegEx character class:

$str = "one-two_three"

$str -replace "[-_]", " "Copy

one two threeCopy

You can also remove characters entirely by replacing them with an empty string:

$str = "Hello... world!!!"

$str -replace "[.!]", ""Copy

Hello worldCopy

Replacing Text in a File

You can combine Get-Content and Set-Content with -replace to find and replace text inside a file:

(Get-Content -Path "config.txt") -replace "old-value", "new-value" |
    Set-Content -Path "config.txt"Copy

The parentheses around Get-Content are important — they force PowerShell to read the entire file before writing back to it. Without them, you’ll get a file lock error since you’d be reading and writing to the same file at the same time.