I'm looking for a way to export all lines from within a text file where part of the line matches a certain string. The string is actually the first 4 bytes of the file and I'd like to keep the command to only checking those bytes; not the entire row. I want to write the entire row. How would I go about this?
I am using Windows only and don't have the option to use many other tools that might do this.
Thanks in advance for any help.
Do you want to perform a simple "grep"? Then try this
select-string .\test.txt -pattern "\Athat" | foreach {$_.Line} or this (very similar regex), also writes to an outfile
select-string .\test.txt -pattern "^that" | foreach {$_.Line} | out-file -filepath out.txt This assumes that you want to search for a 4-byte string "that" at the beginning of the string , or beginning of the line, respectively.
select-string .\test.txt -pattern "^.{149}$([char]127){3}" | foreach {$_.Line} | out-file -filepath out.txt That'll skip the first 149 characters, and then looks for 3 char 127s.Something like the following Powershell function should work for you:
function Get-Lines { [cmdletbinding()] param( [string]$filename, [string]$prefix ) if( Test-Path -Path $filename -PathType Leaf -ErrorAction SilentlyContinue ) { # filename exists, and is a file $lines = Get-Content $filename foreach ( $line in $lines ) { if ( $line -like "$prefix*" ) { $line } } } } To use it, assuming you save it as get-lines.ps1, you would load the function into memory with:
. .\get-lines.ps1 and then to use it, you could search for all lines starting with "DATA" with something like:
get-lines -filename C:\Files\Datafile\testfile.dat -prefix "DATA" If you need to save it to another file for viewing later, you could do something like:
get-lines -filename C:\Files\Datafile\testfile.dat -prefix "DATA" | out-file -FilePath results.txt Or, if I were more awake, you could ignore the script above, use a simpler solution such as the following one-liner:
get-content -path C:\Files\Datafile\testfile.dat | select-string -Pattern "^DATA" Which just uses the ^ regex character to make sure it's only looking for "DATA" at the beginning of each line.
To get all the lines from c:\somedir\somefile.txt that begin with 'abcd' :
(get-content c:\somedir\somefile.txt) -like 'abcd*' provided c:\somedir\somefile.txt is not an unusually large (hundreds of MB) file. For that situation:
get-content c:\somedir\somefile.txt -readcount 1000 | foreach {$_ -like 'abcd*'} 