Remove empty lines from a file using Powershell.

I needed to remove the blank lines from a file.

Normally when I need to do this, I use a regular expression in TextPad. (replace "\r\n\r\n" with "\r\n"... and iterate) -- but TextPad wasn't available on this machine, and I couldn't connect to the internet to grab it.

So I fired up PowerShell and messed around with the syntax until it worked.

gc c:\FileWithEmptyLines.txt | where {$_ -ne ""} > c:\FileWithNoEmptyLines.txt

I don't know if that was the prettiest way to do it -- but I got the result I needed ;-)

The nicest thing was that I didn't need to look anything up -- I just tried variations until I got the result I wanted. I didn't remember the syntax of the 'where' statement or the 'not equal to' operator -- I guessed and got them right within one or two guesses. Nice language design, Bruce!

(I didn't even remember the command 'gc' -- but since i wanted the powershell equivalent of the 'type' command, so i entered 'alias type' and found 'Get-Content' is the powershell equivalent of 'Type' which i guessed was also known as just 'gc')

Reinventing the wheel?
cat FileWithEmptyLines.txt | grep -v ^$ > FileWithNoEmptyLines.txt

or even just:
grep -v ^$ FileWithEmptyLines.txt > FileWithNoEmptyLines.txt

Why do we need another set of shell commands for people to have to remember?

grep? cat? hello?? not exactly standard on a windows machine.

besides -- powershell does a whole lot more than any unix shell can do.

@{anonymous coward}

>another set of shell commands for people
>to have to remember

no -- you miss the point. I didn't have to remember anything, and i didn't even need to use regular expressions in this case.

If you type 'Cat' in powershell, then the alias 'Cat' is used which is just an alias to 'Get-Content'

So that is one less thing to have to remember.

Although there's no syntactic equivalent to grep, you could use this syntax:

cat c:\HasEmptyLines.txt | where {$_ -notmatch "^$" } > c:\NoEmptyLines.txt

Here's two ways to measure the length of the resulting file...

$count=0 ;; gc c:\NoEmptyLines.txt | foreach{$count++;} ;; $count

gc c:\NoEmptyLines.txt | Measure-Object

and here's a way to analyze a multi-line string (without putting it into a file first) (and you'd have to escape any double quote chars)

> "
>> cdcdscsdcsdd
>> " | where {$_ -ne "fred"} > c:\fred3.txt
>>

And if the script is going to contain " characters but you don't wanna escape them...

--> Running a Powershell comparison against a multiple line piece of text (without putting it into a file first)
> @"
>> cdcdscsdcsdd
>> "@ | where {$_ -ne "fred"} > c:\fred3.txt
>>

@Bert: Unix tools are certainly standard on my machine, can't live without Cygwin.

yeh but barrkel, you're a special case. ;-)

people who work on compilers are generally very far outside any kind of normal consideration.

no need to use two files for this

(get-content C:\File.txt) | where {$_ -ne ""} | out-file c:\file.txt

will read and write from/to the same file

Here I'am sharing my script which list all domain controllers from my domain and then delete the empty (blank) lines from the generated file:

$file = "\\WDC1A\E$\ScriptsAD\DCList1.txt"
import-module ActiveDirectory
Get-ADDomainController -Server domain.com -Filter * | Sort-Object name | Format-Table name -HideTableHeaders | Out-File $file

Get-Content $file | where {$_.Length -ne 0} | Out-File "$file`.tmp"
Move-Item "$file`.tmp" $file -Force

My version:
(gc file.txt) | ? {$_.trim() -ne "" } | set-content file.txt

The parenthesis causes the command to finish before proceeding through the pipline. Or else the file would be locked and we couldn't write to it.
The trim() method removes lines that contain spaces but nothing else which is what I needed in my case.

PowerShell is pretty handy!

Remove empty lines from a file using Powershell.

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