PowerShell equivalent to grep -f

Question

I\'m looking for the PowerShell equivalent to grep --file=filename. If you don\'t know grep, filename is a text file where each line has a regular

Answer 1

but select-String doesn't seem to have this option.

Correct. PowerShell is not a clone of *nix shells' toolset.

However it is not hard to build something like it yourself:

$regexes = Get-Content RegexFile.txt | 
           Foreach-Object { new-object System.Text.RegularExpressions.Regex $_ }

$fileList | Get-Content | Where-Object {
  foreach ($r in $regexes) {
    if ($r.IsMatch($_)) {
      $true
      break
    }
  }
  $false
}

Answer 2

The -Pattern parameter in Select-String supports an array of patterns. So the one you're looking for is:

Get-Content .\doc.txt | Select-String -Pattern (Get-Content .\regex.txt)

This searches through the textfile doc.txt by using every regex(one per line) in regex.txt

Answer 3

I find out a possible method by "filter" and "alias" of PowerShell, when you want use grep in pipeline output(grep file should be similar):

first define a filter:

filter Filter-Object ([string]$pattern)
{
    Out-String -InputObject $_ -Stream | Select-String -Pattern "$pattern"
}

then define alias:

New-Alias -Name grep -Value Filter-Object

final, put the former filter and alias in your profile:

$Home[My ]Documents\PowerShell\Microsoft.PowerShell_profile.ps1

Restart your PS, you can use it:

alias | grep 'grep'

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relevent Reference

1. alias: Set-Aliasenter link description here New-Aliasenter link description here

2. Filter(Special function)enter link description here

3. Profiles(just like .bashrc for bash):enter link description here

4. out-string(this is the key)enter link description here:in PowerShell Output is object-basedenter link description here，so the key is convert object to string and grep the string.

5. Select-Stringenter link description here:Finds text in strings and files