I am using Ubuntu with kernel 2.6.31.1. I am not finding dos2unix.
Can you please help me about how I can install this from any source or any equivalent one for dos2unix. Or any solution to remove "^M" character in the source files that I want to compile now.
Thanks,
-KDB Learner

check man tofrodos for how to use it. It looks about the same as dos2unix which I did not find in the repository.

There's a tool similar to it called flip available in the debian repositories, so it's probably also in *buntu.

You can also simply use sed to convert the line endings. This page includes the proper code (about one page down), along with many other useful one-liners.

SOLVED
Thanks to ajlewis2 and David the H.
I got the solution now. I installed sudo apt-get install tofrodos. Also doing the "man tofrodos" gave me the two commands "fromdos" and "todos". Using "todos -f * *", I was able fix the "^M" issue in all the files in a directory.
-KDBlearn

It looks like it's in package tofrodos in debian.

# apt-get install tofrodos

$ apt-file find dos2unix

Assuming that apt-file is installed and updated.

# apt-get install apt-file
# apt-file update

dos2unix and unix2dos just change the 0x0D0A to 0x0A and similar. Because the OS's differ in how text files end their lines. 0x0D is carraige return. And 0x0A is linefeed. \r\n for echo commands and the likes. I don't quite recall which is which by a quick echo to a file and hexedit / hexdump should show that detail. It's a printer thing. Back when you typed things on mechanical devices. There was one way to bring the roll back to the start of the line, and nother to feed the paper up a line. Carraige return and line feed. Dos/windows does 0x0D0A, *nix does 0x0A, and Mac does 0x0D or something like that. I probably got something changed around in there somewhere. And it's part of the reason that you have to tell ftp clients which transfer mode (binary/ascii) when getting data from that method. So that the ftp client can do the dos2unix / unix2dos conversion for you on text files. Based on what it thinks your client / platform is.