Loop through files in a directory using PowerShell - powershell

Question

How can I change the following code to look at all the .log files in the directory and not just the one file?
I need to loop through all the files and delete all lines that do not contain "step4" or "step9". Currently this will create a new file, but I'm not sure how to use the for each loop here (newbie).
The actual files are named like this: 2013 09 03 00_01_29.log. I'd like the output files to either overwrite them, or to have the SAME name, appended with "out".
$In = "C:\Users\gerhardl\Documents\My Received Files\Test_In.log"
$Out = "C:\Users\gerhardl\Documents\My Received Files\Test_Out.log"
$Files = "C:\Users\gerhardl\Documents\My Received Files\"
Get-Content $In | Where-Object {$_ -match 'step4' -or $_ -match 'step9'} | `
Set-Content $Out

Answer 1

Give this a try:
Get-ChildItem "C:\Users\gerhardl\Documents\My Received Files" -Filter *.log |
Foreach-Object {
$content = Get-Content $_.FullName
#filter and save content to the original file
$content | Where-Object {$_ -match 'step[49]'} | Set-Content $_.FullName
#filter and save content to a new file
$content | Where-Object {$_ -match 'step[49]'} | Set-Content ($_.BaseName + '_out.log')
}

Answer 2

To get the content of a directory you can use
$files = Get-ChildItem "C:\Users\gerhardl\Documents\My Received Files\"
Then you can loop over this variable as well:
for ($i=0; $i -lt $files.Count; $i++) {
$outfile = $files[$i].FullName + "out"
Get-Content $files[$i].FullName | Where-Object { ($_ -match 'step4' -or $_ -match 'step9') } | Set-Content $outfile
}
An even easier way to put this is the foreach loop (thanks to #Soapy and #MarkSchultheiss):
foreach ($f in $files){
$outfile = $f.FullName + "out"
Get-Content $f.FullName | Where-Object { ($_ -match 'step4' -or $_ -match 'step9') } | Set-Content $outfile
}

Answer 3

If you need to loop inside a directory recursively for a particular kind of file, use the below command, which filters all the files of doc file type
$fileNames = Get-ChildItem -Path $scriptPath -Recurse -Include *.doc
If you need to do the filteration on multiple types, use the below command.
$fileNames = Get-ChildItem -Path $scriptPath -Recurse -Include *.doc,*.pdf
Now $fileNames variable act as an array from which you can loop and apply your business logic.

Answer 4

Other answers are great, I just want to add... a different approach usable in PowerShell:
Install GNUWin32 utils and use grep to view the lines / redirect the output to file http://gnuwin32.sourceforge.net/
This overwrites the new file every time:
grep "step[49]" logIn.log > logOut.log
This appends the log output, in case you overwrite the logIn file and want to keep the data:
grep "step[49]" logIn.log >> logOut.log
Note: to be able to use GNUWin32 utils globally you have to add the bin folder to your system path.