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.