Introduction </h3>
For any console sufers like me, having a toolbox filled with basic tools is essential. Linux provides those commands and most IT person, developer and Administrator will know them. One of the first Linux commands that many users learn is grep Grep’s provide the ability to search plain text for a RegEx pattern in a set of files. Grep can search files in a given directory or streamed input to output matches.
If you want to grep in PowerShell, you can use the provided Select-String cmdlet. Unfortunately, Select-String needs a few improvements in order to be user-friendly like Linux’s grep.
I’m not going to explain the basics of Select-String as there’s already tons of articles on it’s usage online. Let’s focus on how to make our own grep based on Select-String instead. That means you are expected to know how to use Select-String by itself.
Define the Scripts Requirements
We want to add the ability to
- search recursively in many folders
- only search specific file types
- exclude some folders / files from search by name
- handle files with no newline (like huge css.min)
- option to get psobjects
search recursively in many folders
To search recursively in many folders for example, you need also check the current directory and the subfolders (-Recurse) or you need additional filter for files you wanna check, you can use the Get-Childitem before Select-String like this.
Get-ChildItem C:\temp -Filter *.log -Recurse | Select-String "FooBar"
only search specific file types
Lets use Get-ChidItems and add a file filter argument, so that we can filter only certain file types:
# List all files but not those with those words in the name: Foo,Bar,Please,Not,This
$Filter = '*.log'
Get-ChildItem "c:\Logs" -File -Filter $Filter | Select-String -pattern $Pattern
exclude some folders / files from search by name
To exclude some folders / files from search by name, we can use the Get-ChildItems and add a Where clause with -notmatch. See when you want to add multiple -notmatch condition to a function call, you can just separate the different words by a pipe (|) character like this:
# List all files but not those with those words in the name: Foo,Bar,Please,Not,This
Get-ChildItem "c:\Logs" -File -Filter $Filter | where FullName -notmatch "Foo|Bar|Please|Not|This"
So we will have somethis like this:
$Exclude = @('words','to','remove')
[string]$exclude_string = ''
ForEach($toexclude in $Exclude){
$exclude_string += "$toexclude|"
}
$exclude_string = $exclude_string.Trim('|')
Write-Verbose " Excluding this string in names: $exclude_string"
$SearchList = Get-ChildItem -Path $Path -File -Filter $Filter | where FullName -notmatch "$exclude_string" | Select-String -pattern $Pattern
Final function
After we get the Select-String results and process them so that we don’t have screen overflow with huge onle line files, and after we create the option to output a list of psobjects, we get this:
function Search-Pattern
{
<#
.SYNOPSIS
Cmdlet to find in files (grep)
.DESCRIPTION
Cmdlet to find in files (grep)
.PARAMETER Pattern
What to look for in the files
.PARAMETER Extension
File Extension, just the Extension, no *
.PARAMETER Path
Path for search
.PARAMETER Exclude
Exclude string array
.PARAMETER Short
Output short file names
.PARAMETER List
Output as list of psobjects
.PARAMETER Recurse
Recurse in subdirectories
.EXAMPLE
Search-Pattern -Pattern 'g.png' -Extension "txt"
Search-Pattern -Pattern 'g.png' -Exclude @("_site","jekyll-metadata","bower_components","jekyll-cache")
#>
[CmdletBinding(SupportsShouldProcess)]
Param
(
[Parameter(Position = 0,Mandatory=$true, HelpMessage="Pattern to search for")]
[Object]$Pattern,
[Parameter(Mandatory=$false, HelpMessage="File filter")]
[Alias('f')]
[string]$Filter = '*.*',
[Parameter(Mandatory=$false, HelpMessage="Path for search")]
[Alias('p')]
[string]$Path,
[Parameter(Mandatory=$false, HelpMessage="Exclude string array")]
[Alias('x')]
[string[]]$Exclude,
[Parameter(Mandatory=$false, HelpMessage="Output short file names")]
[Alias('s')]
[switch]$Short,
[Parameter(Mandatory=$false, HelpMessage="Output as list of psobjects")]
[Alias('l')]
[switch]$List,
[Parameter(Mandatory=$false, HelpMessage="Recurse in subdirectories")]
[Alias('r')]
[switch]$Recurse=$true
)
[system.collections.arraylist]$Results = [system.collections.arraylist]::new()
[Microsoft.PowerShell.Commands.MatchInfo[]]$SearchList;
[string]$CurrentPath = (Get-Location).Path
if([string]::IsNullOrEmpty($Path)){
$Path = $CurrentPath
}
Write-Verbose "Search-Pattern (my grep): looking for a string in files. Path: $Path"
Write-Verbose " Pattern: $Pattern"
Write-Verbose " Short: $Short"
Write-Verbose " Recurse: $Recurse"
Write-Verbose " Using Extension filter: $Filter"
if($Exclude.Count -gt 0){
[string]$exclude_string = ''
ForEach($toexclude in $Exclude){
$exclude_string += "$toexclude|"
}
$exclude_string = $exclude_string.Trim('|')
Write-Verbose " Excluding this string in names: $exclude_string"
$SearchList = Get-ChildItem -Path $Path -File -Filter $Filter -Recurse:$Recurse | where FullName -notmatch "$exclude_string" | Select-String -pattern $Pattern
}
else{
$SearchList = Get-ChildItem -Path $Path -File -Filter $Filter -Recurse:$Recurse | Select-String -pattern $Pattern
}
ForEach($match in $SearchList){
$Path = $match.Path
$Path = $Path.Replace($CurrentPath,'.')
if($Short){
$Path = $match.FileName
}
$SearchPattern = $Pattern.Replace('\','')
$Line = $match.Line.Trim()
$Index = $Line.IndexOf($SearchPattern)
if($Index -eq -1){$Index = 0}
$LineNumber = $match.LineNumber
$Length = $Line.Length
if($Length -gt 80){
if($Index -gt 80){
$Line = $Line.SubString($Index -2,$SearchPattern.Length + 15)
}else{
$Line = $Line.SubString(0,80)
}
}
$o = [pscustomobject]@{
Path = $Path
LineNumber = $LineNumber
Index = $Index
Line = $Line
}
if($List){
[void]$Results.Add($o)
}else{
Write-Output "$Path`:$LineNumber,$Index`t$Line"
}
}
if($List){
$Results
}
}
New-Alias -Name 'grep' -Value -Search-Pattern -Force
