Read file line by line in PowerShell
Solution 1:
Not much documentation on PowerShell loops.
Documentation on loops in PowerShell is plentiful, and you might want to check out the following help topics: about_For
, about_ForEach
, about_Do
, about_While
.
foreach($line in Get-Content .\file.txt) {
if($line -match $regex){
# Work here
}
}
Another idiomatic PowerShell solution to your problem is to pipe the lines of the text file to the ForEach-Object
cmdlet:
Get-Content .\file.txt | ForEach-Object {
if($_ -match $regex){
# Work here
}
}
Instead of regex matching inside the loop, you could pipe the lines through Where-Object
to filter just those you're interested in:
Get-Content .\file.txt | Where-Object {$_ -match $regex} | ForEach-Object {
# Work here
}
Solution 2:
Get-Content
has bad performance; it tries to read the file into memory all at once.
C# (.NET) file reader reads each line one by one
Best Performace
foreach($line in [System.IO.File]::ReadLines("C:\path\to\file.txt"))
{
$line
}
Or slightly less performant
[System.IO.File]::ReadLines("C:\path\to\file.txt") | ForEach-Object {
$_
}
The foreach
statement will likely be slightly faster than ForEach-Object
(see comments below for more information).
Solution 3:
The almighty switch
works well here:
'one
two
three' > file
$regex = '^t'
switch -regex -file file {
$regex { "line is $_" }
}
Output:
line is two
line is three