remove empty lines from text file with PowerShell

I found a nice one liner here >> http://www.pixelchef.net/remove-empty-lines-file-powershell. Just tested it out with several blanks lines including newlines only as well as lines with just spaces, just tabs, and combinations.

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

See the original for some notes about the code. Nice :)

This piece of code from Randy Skretka is working fine for me, but I had the problem, that I still had a newline at the end of the file.

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

So I added finally this:

$content = [System.IO.File]::ReadAllText("file.txt")
$content = $content.Trim()
[System.IO.File]::WriteAllText("file.txt", $content)

You can use -match instead -eq if you also want to exclude files that only contain whitespace characters:

@(gc c:\FileWithEmptyLines.txt) -match '\S'  | out-file c:\FileWithNoEmptyLines

Not specifically using -replace, but you get the same effect parsing the content using -notmatch and regex.

(get-content 'c:\FileWithEmptyLines.txt') -notmatch '^\s*$' > c:\FileWithNoEmptyLines.txt

To resolve this with RegEx, you need to use the multiline flag (?m):

((Get-Content file.txt -Raw) -replace "(?m)^\s*`r`n",'').trim() | Set-Content file.txt

You can't do replacing, you have to replace SOMETHING with SOMETHING, and you neither have both.

This removes trailing whitespace and blank lines from file.txt

PS C:\Users\> (gc file.txt) | Foreach {$_.TrimEnd()} | where {$_ -ne ""} | Set-Content file.txt

(Get-Content c:\FileWithEmptyLines.txt) | 
    Foreach { $_ -Replace  "Old content", " New content" } | 
    Set-Content c:\FileWithEmptyLines.txt;

If you actually want to filter blank lines from a file then you may try this:

(gc $source_file).Trim() | ? {$_.Length -gt 0}

file

PS /home/edward/Desktop> Get-Content ./copy.txt

[Desktop Entry]

Name=calibre Exec=~/Apps/calibre/calibre

Icon=~/Apps/calibre/resources/content-server/calibre.png

Type=Application*

Start by get the content from file and trim the white spaces if any found in each line of the text document. That becomes the object passed to the where-object to go through the array looking at each member of the array with string length greater then 0. That object is passed to replace the content of the file you started with. It would probably be better to make a new file... Last thing to do is reads back the newly made file's content and see your awesomeness.

(Get-Content ./copy.txt).Trim() | Where-Object{$_.length -gt 0} | Set-Content ./copy.txt

Get-Content ./copy.txt

Set-Content -Path "File.txt" -Value (get-content -Path "File.txt" | Select-String -Pattern '^\s*$' -NotMatch)  

This works for me, originally got the line from here and added Joel's suggested '^\s*$': Using PowerShell to remove lines from a text file if it contains a string

This will remove empty lines or lines with only whitespace characters (tabs/spaces).

[IO.File]::ReadAllText("FileWithEmptyLines.txt") -replace '\s+\r\n+', "`r`n" | Out-File "c:\FileWithNoEmptyLines.txt"

Get-Content returns immutable array of rows. You can covert this to mutable array and delete neccessary lines by index.Particular indexex you can get with match. After that you can write result to new file with Set-Content. With this approach you can avoid empty lines that powershell replace tool leaves when you try to replace smthing with "". Note that I dont guarantee perfect perfomance. Im not a professional powershell developer))

$fileLines = Get-Content $filePath
$neccessaryLine = Select-String -Path  $filePath -Pattern 'something'
if (-Not $neccessaryLine) { exit }
$neccessaryLineIndex = $neccessaryLine.LineNumber - 1
$updatedFileContent = [System.Collections.ArrayList]::new($fileLines)
$updatedFileContent.RemoveAt($neccessaryLineIndex)
$updatedHostsFileContent.RemoveAt($domainInfoLineIndex - 1)
$updatedHostsFileContent | Set-Content $hostsFilePath