Powershell equivalent to sponge in moreutils?

There's a GNU program called sponge that soaks up input before writing to a file so you can do something like this: cat myFile | grep "myFilter" | sponge myFile

Is there a powershell equivalent, so I can work on a file in place, without having to pipe to a temporary file?

Thanks

In Powershell, judicious use of parentheses will force an operation to completely finish before passing data to the next command in the pipeline. The default for piping Get-Content is to pipe line by line to the next command, but with parentheses it must form a complete data set (e.g., load all lines) before continuing:

(Get-Content myFile) | Select-String 'MyFilter' | Set-Content myFile

An alternative that may use less memory (I have not benchmarked it) is to only force the results of Select-String to complete before continuing:

(Get-Content myFile | Select-String 'MyFilter') | Set-Content myFile

You could also assign things to a variable as an additional step. Any technique will load the contents into the Powershell session's memory, so be careful with big files.

Addendum: Select-String returns MatchInfo objects. Using Out-File adds pesky extra blank lines due to the way it tries to format the results as a string, but Set-Content correctly converts each object to its own string as it writes, producing better output. Being that you're coming from *nix and are used to everything returning strings (whereas Powershell returns objects), one way to force string output is to pipe them through a foreach that converts them:

(Get-Content myFile | Select-String 'MyFilter' | foreach { $_.tostring() }) | Set-Content myFile

You can try this :

(Get-content myfile) | where {$_ -match "regular-expression"} | Set-content myfile

or

${full-path-file-name-of-myfile} | where {$_ -match "regular-expression"} | add-content Anotherfile

more easier to keep in mind

two other ways come to mind - they are both the same really just one is a function the other is on the command line. (I don't know sponge on unix so I can't say for certain they mimic it).

here's the first on the command line

Get-Content .\temp.txt | 
    Select-String "grep" | 
    foreach-object -begin { [array] $out  = @()} -process { $out = $out + ($_.tostring())} -end {write-output $out}

and the second is two create a function to do it

function sponge {
    [cmdletbinding()]
    Param(
        [Parameter(
            Mandatory = $True,
            ValueFromPipeline = $True)]
        [string]$Output
    )
    Begin {
        [array] $out = @()
    }
    Process {
        $out = $out + $Output
    }
    End {
        Write-Output $Out
    }
}


Get-Content .\temp2.txt | Select-String "grep" | sponge

HTH, Matt