Unless you use binmode on your input file, CRLF gets converted to LF on read.
Unless you use binmode on your output file, LF gets converted to CRLF on write.

To convert a Windows file to a unix file (on any machine):

binmode($fh_in);
binmode($fh_out);
while (<$fh_in>) {
   s/\x0D\x0A/\x0A/g;
   print $fh_out $_;
}
[download]

perl -pe "s/\r(?=\n)//" winfile.txt > unixfile.txt
[download]

perl -i.bak -pe "s/\r(?=\n)//" winfile.txt > unixfile.txt
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perl -e "print \"foo\r\nbar\r\nstuff\";" > f.txt
perl -pe "s/(\s)/'['.ord($1).']'/esg" f.txt
REM output:    foo[13][10]bar[13][10]stuff
perl -i.bak -pe "s/\r(?=\n)//" f.txt
perl -pe "s/(\s)/'['.ord($1).']'/esg" f.txt
REM output:    foo[10]bar[10]stuff
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None of those work in Windows. (I presume that's what you meant by DOS.)

>echo Hello > winfile.txt

>echo World >> winfile.txt

>perl -pe "s/\r(?=\n)//" winfile.txt > unixfile.txt

>debug unixfile.txt
-rcx
CX 0010
:
-d100 l10
0AF7:0100  48 65 6C 6C 6F 20 0D 0A-57 6F 72 6C 64 20 0D 0A   Hello ..W
+orld ..
-q
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Well, they might work with a simulated unix environment in Windows (like cygwin), but that's an entirely different world.

The earlier posts in this thread not only provided the solution, they explained this problem and the workaround.

If it's one-liners you wanted,

• Works anywhere:
  perl -pe "BEGIN { binmode STDIN; binmode STDOUT } s/\x0D(?=\x0A)//" winfile.txt > unixfile.txt
• Works on Windows:
  perl -pe "BEGIN { binmode STDIN }" winfile.txt > unixfile.txt
• Works on unix:
  perl -ple 'BEGIN { $/="\r\n" }' winfile.txt > unixfile.txt

I tested (in a DOS window on WindowsXP, striaght -- no cygwin) all of what i posted .. I don't understand -- why doesn't it work??

C:\foo>type foo.bat
@echo OFF

echo "making test file"
perl -e "print \"foo\r\nbar\r\nstuff\";" > f.txt
echo "showing test file"
perl -pe "s/(\s)/'['.ord($1).']'/esg" f.txt

echo "altering file"
perl -i.bak -pe "s/\r(?=\n)//" f.txt
echo "showing result"
perl -pe "s/(\s)/'['.ord($1).']'/esg" f.txt

C:\foo>foo.bat
"making test file"
"showing test file"
foo[13][10]bar[13][10]stuff
"altering file"
"showing result"
foo[10]bar[10]stuff
C:\foo>
[download]

Unfortunately, Windows has been known to not play well with other OSes, and thus, there are no "dos2unix" or "unix2dos" commands built-in. :-( I haven't recently checked if there are any open-source add-ins or commands to do this.

Some text editor programs allow you to change the file attributes. I happen to use the open-source Crimson Editor (now called Emerald Editor). In Crimson Editor, the menu comand "Document | File Format" will give you a choice between DOS format (CR/LF), Unix format (LF only), or Mac format (CR only).

And then there's Cygwin. :-)