Comma is needed before "but" which is joining two sentences.

documentationsupport/AtulJha.tex

@@ -14,7 +14,7 @@
 
 I started reading the book and to my surprise the definition of hacker was
 ``someone who likes solving problems and overcoming limits''. It also said
-``hackers build things, crackers break them.'' Alas I wanted to be a cracker but
+``hackers build things, crackers break them.'' Alas I wanted to be a cracker, but
 this book brought me to the other world of hacking. I kept reading the book and
 encountered various new terms like GNU/Linux, mailing list, Linux user group,
 IRC, Python and many more. 
@@ -41,7 +41,7 @@
 One fine day I got an email about a monthly Linux user group meetup. I
 needed answers for my many questions. I met Karunakar there and he
 asked me to bring my computer to his office as he had the whole Debian
-repository available there. Debian was new for me but I was
+repository available there. Debian was new for me, but I was
 satisfied with the fact that finally I will be able to play music on
 Linux. The next day I was in his office after carrying my computer on the
 over-crowded bus -- it was fun. In a few hours, Debian was up and running on my