Difference between ForEach and ForEach-Object in powershell

Question

Is there any difference between ForEach and ForEach-Object ?

I have a small code like this, works fine

$txt = Get-Content 'C:\temp\000.txt' $result = foreach ($line in $txt) {$line.replace(".ini","")} $result | out-file 'c:\temp\001.txt' 

But if i use 'ForEach-Object', I got errors....

$txt = Get-Content 'C:\temp\000.txt' $result = foreach-object ($line in $txt) {$line.replace(".ini","")} $result | out-file 'c:\temp\001.txt' 

Why ? and how to output the loop results by using ForEach-Object

Answer 1

foreach is an alias of ForEach-Object but it appears to also be a keyword (which is confusing).

The foreach ($<item> in $<collection\>){<statement list>} syntax you are using is help about_foreach.

The foreach as ForEach-Object alias is help ForEach-Object.

The keyword foreach operates over each $<item> in the $<collection> as given in the () bit.

The alias foreach/function ForEach-Object operates over each item of the collection it receives as input.

Answer 2

They're different commands for different purposes. The ForEach-Object cmdlet is used in the pipeline, and you use either $PSItem or $_ to refer to the current object in order to run a {scriptblock} like so:

1..5 | ForEach-Object {$_}  >1 >2 >3 >4 >5 

Now, you can also use a very similiar looking keyword, ForEach, at the beginning of a line. In this case, you can run a {scriptblock} in which you define the variable name, like this:

ForEach ($number in 1..5){$number} >1 >2 >3 >4 >5 

The core difference here is where you use the command, one is used in the midst of a pipeline, while the other starts its own pipeline. In production style scripts, I'd recommend using the ForEach keyword instead of the cmdlet.