# IN UNIX ENVIRONMENT: convert DOS newlines (CR/LF) to Unix format.
sed 's/.$//'               # assumes that all lines end with CR/LF
sed 's/^M$//'              # in bash/tcsh, press Ctrl-V then Ctrl-M
sed 's/\x0D$//'            # works on ssed, gsed 3.02.80 or higher

# IN UNIX ENVIRONMENT: convert Unix newlines (LF) to DOS format.
sed "s/$/'echo -e \\\r'/"            # command line under ksh
sed 's/$'"/'echo \\\r'/"             # command line under bash
sed "s/$/'echo \\\r'/"               # command line under zsh
sed 's/$/\r/'                        # gsed 3.02.80 or higher

# IN DOS ENVIRONMENT: convert Unix newlines (LF) to DOS format.
sed "s/$//"                          # method 1
sed -n p                             # method 2

# IN DOS ENVIRONMENT: convert DOS newlines (CR/LF) to Unix format.
# Can only be done with UnxUtils sed, version 4.0.7 or higher. The
# UnxUtils version can be identified by the custom "--text" switch
# which appears when you use the "--help" switch. Otherwise, changing
# DOS newlines to Unix newlines cannot be done with sed in a DOS
# environment. Use "tr" instead.
sed "s/\r//" infile >outfile         # UnxUtils sed v4.0.7 or higher
tr -d \r <infile >outfile            # GNU tr version 1.22 or higher



http://sed.sourceforge.net/sed1line.txt

-P, --perl-regexp
              Interpret PATTERN as a Perl regular expression.  This option  is
              not supported in FreeBSD.