[SOLVED] Adding Arguments to PowerShell Alias Functions

Issue

I just installed grep on PowerShell through chocolatey and using it, I could search for a string I want from any text as shown below:

href="https://i.stack.imgur.com/rBRGt.png" rel="nofollow noreferrer">

However, I don't want to always have to type grep --color, hence I tried to make an alias on my $profile like this:

Function grep($a1){
  grep --color $a1
}

but then I would get an error:

So I tried:

Set-Alias grep "grep --color"

but then I get yet another error:

I can't think of anything else to make this work, hence I'd really appreciate any help.

Solution

Aliases in PowerShell are mere alternative names for other commands, so you cannot use them to include arguments to pass to these other commands.

You therefore indeed need a function, but since you're naming it the same as the external program you're wrapping, you need to disambiguate so as to avoid an infinite recursion:

function grep {
  $externalGrep = Get-Command -Type Application grep
  if ($MyInvocation.ExpectingInput) { # pipeline (stdin) input present
    # $args passes all arguments through.
    $input | & $externalGrep --color $args
  } else {
    & $externalGrep --color $args
  }
}

Note:

• Use of the automatic $input variable to relay pipeline (stdin) input means that this input is collected (buffered) in full first. More effort is needed to implement a true streaming solution - see this answer for an example.

Alternatively - at least on Unix-like platforms - you can set an environment variable to control grep's coloring behavior, which may obviate the need for a function wrapper; the equivalent of the --color parameter is to set $env:GREP_COLOR='always' (the other supported values are 'never' and 'auto').

Answered By - mklement0

Answer Checked By - David Marino (WPSolving Volunteer)