for /r %%v in (*.xls) do ssconvert "%%v" "%%vx"
a couple have people have asked me to explain this, so:
Part 1: for /r %%v in (*.xls)
This part returns an array of files in the current directory that have the xls extension. The %% may look a little curious. This is basically the special % character from command line as used in %PATH% or %TEMP%. To use it in a batch file we need to escape it like so: %%PATH%% or %%TEMP%%. In this case we are simply escaping the temporary variable v, which will hold our array of filenames.
We are using the /r switch to search for files recursively, so any matching files in child folders will also be located.
Part 2: do ssconvert "%%v" "%%vx"
This second part is what will get executed once per matching filename, so if the following files were present in the current folder:
c:\temp\mySheet.xls,
c:\temp\mySheet_yesterday.xls,
c:\temp\mySheet_20160902.xls
the following commands would be executed:
ssconvert "c:\temp\mySheet.xls" "c:\temp\mySheet.xlsx"
ssconvert "c:\temp\mySheet_yesterday.xls" "c:\temp\mySheet_yesterday.xlsx"
ssconvert "c:\temp\mySheet_20160902.xls" "c:\temp\mySheet_20160902.xlsx"