I installed Puttygen on windows using: putty-64bit-0.79-installer.msi (which I downloaded from the official Puttygen website).

Except that when I go to Windows cmd and run puttygen -V, I get the error "Unrecognised option -V". What’s worse is that this message is displayed regardless of the option entered.

I have to use puttygen as a batch script without going through the interface to transform an id_rsa file into id_rsa.ppk.

>Solution :

Windows PuTTYgen is mostly GUI only. It seems that you expect it to support the command-line options that Linux console puttygen does. It does not.

Instead, you can use WinSCP console, which supports some console puttygen functionality:

winscp.com /keygen id_rsa -o id_rsa.ppk

WinSCP does not support the -O switch, but the -O private is the default (and the only) conversion it supports.

(I’m the author of WinSCP)