Vim (vi improved) provides a rapid way to change the format from dos to unix and viceversa.
After you have opened your text file, just type the following command in vim:
:set fileformat=unix
to change the format to unix, or type:
:set fileformat=dos
to change the format to dos format, or type:
:set fileformat=mac
to change the format to Macintosh format.
You can also use the contract form for fileformat typing the following command:
:set ff=<format> (dos, unix, mac)
You can also do massive conversion using the shell and vim:
# vim +"argdo set ff=<format>" +wqa <file_list>
for example
# vim +"argdo set ff=<format>" +wqa *.c
This command will change the format for all c source code file in the current directory.