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August 21 hacks: powershell tail function This is my first blog post. It is a powershell script I wrote for my coworker when SQL Server figured it would be cool to make a log file that was several hundred GB. I went on a short description of Unix' "tail". I didn't help much as the script doesn't work on SQL Server log files. It works with everything else I tried, though. Hopefully eventually somebody will google this page and save themselves some time. Let me know if I screwed up, and more importantly, how. Usage: tail <file> <howManyLines> function tail( $file, $n = 1 ) { $stream = new-object system.io.fileStream( $file, [system.io.fileMode]::open, [system.io.fileAccess]::read ) $line = new-object system.text.stringBuilder $lines = @() for ( $p = -2; $p -gt 0 - $stream.length; $p -= 2 ) { $empty = $stream.seek( $p, [system.io.seekOrigin]::end ) $bytes = [byte[]]( $stream.readByte(), $stream.readByte() ) $chars = [system.text.asciiencoding]::ascii.getchars( $bytes ) [array]::reverse( $chars ) foreach ( $char in $chars ) { $empty = $line.insert( 0, $char ) } $l = $line.toString() if ( $l.contains( [environment]::newline ) ) { $lines = @( $l.substring( $l.indexOf( [environment]::newline ) + 2 ) ) + $lines $line = new-object system.text.stringbuilder( $l.substring( 0, $l.indexOf( [environment]::newline ) ) ) } if ( $lines.length -ge $n ) { $stream.Close() return $lines } } $stream.Close() return $lines } |
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