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 expression pattern you want to match.

Maybe I'm missing something obvious, but Select-String doesn't seem to have this option.

Answer 1

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 2

PS) new-alias grep findstr
PS) C:\WINDOWS> ls | grep -I -N exe

105:-a---        2006-11-02     13:34      49680 twunk_16.exe
106:-a---        2006-11-02     13:34      31232 twunk_32.exe
109:-a---        2006-09-18     23:43     256192 winhelp.exe
110:-a---        2006-11-02     10:45       9216 winhlp32.exe

PS) grep /?

Answer 3

I'm not familiar with grep but with Select-String you can do:

Get-ChildItem filename.txt | Select-String -Pattern <regexPattern>

You can also do that with Get-Content:

(Get-Content filename.txt) -match 'pattern'

Answer 4

I had the same issue trying to find text in files with powershell. I used the following - to stay as close to the Linux environment as possible.

Hopefully this helps somebody:

PowerShell:

PS) new-alias grep findstr
PS) ls -r *.txt | cat | grep "some random string"

Explanation:

ls       - lists all files
-r       - recursively (in all files and folders and subfolders)
*.txt    - only .txt files
|        - pipe the (ls) results to next command (cat)
cat      - show contents of files comming from (ls)
|        - pipe the (cat) results to next command (grep)
grep     - search contents from (cat) for "some random string" (alias to findstr)

Yes, this works as well:

PS) ls -r *.txt | cat | findstr "some random string"

Answer 5

So I found a pretty good answer at this link: https://www.thomasmaurer.ch/2011/03/powershell-search-for-string-or-grep-for-powershell/

But essentially it is:

Select-String -Path "C:\file\Path\*.txt" -Pattern "^Enter REGEX Here$"

This gives a directory file search (*or you can just specify a file) and a file-content search all in one line of PowerShell, very similar to grep. The output will be similar to:

doc.txt:31: Enter REGEX Here
HelloWorld.txt:13: Enter REGEX Here

Answer 6

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 the 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, so you can use it:

alias | grep 'grep'

---

References

1. alias: Set-Alias here New-Alias here

2. Filter (Special function) here

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

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

5. Select-String here:
   Finds text in strings and files

Answer 7

This question already has an answer, but I just want to add that in Windows there is Windows Subsystem for Linux WSL.

So for example if you want to check if you have service named Elasicsearch that is in status running you can do something like the snippet below in powershell

net start | grep Elasticsearch

Answer 8

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 9

Maybe?

[regex]$regex = (get-content <regex file> |
foreach {
          '(?:{0})' -f $_
        }) -join '|'

Get-Content <filespec> -ReadCount 10000 |
 foreach {
           if ($_ -match $regex)
             {
              $true
              break
             }
         }