tr -d '15' <DOS-file >UNIX-file

sed 's/^M$//'     # DOS to Unix
sed 's/$/^M/'     # Unix to DOS

sed $'s/r$//'     # DOS to Unix
sed $'s/$/r/'     # Unix to DOS

tr -d "r" < file

# 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

perl -pe 'if ( s/rn?/n/g ) { $f=1 }; if ( $f || ! $m ) { s/([^n])z/$1n/ }; $m=1' PCfile.txt

#!/usr/bin/env python
"""
convert dos linefeeds (crlf) to unix (lf)
usage: dos2unix.py <input> <output>
"""
import sys

if len(sys.argv[1:]) != 2:
  sys.exit(__doc__)

content = ''
outsize = 0
with open(sys.argv[1], 'rb') as infile:
  content = infile.read()
with open(sys.argv[2], 'wb') as output:
  for line in content.splitlines():
    outsize += len(line) + 1
    output.write(line + 'n')

print("Done. Saved %s bytes." % (len(content)-outsize))

awk '{ sub("r$", ""); print }' dos.txt > unix.txt

awk '{ sub("r$", ""); print }' dos.txt > unix.txt

perl -pe 's/r$//' < dos.txt > unix.txt

awk -v ORS='rn' '1' unix.txt > dos.txt

cat FILE | tr 'nr' 'n' > FILE

brew install dos2unix

for csv in *.csv; do dos2unix -c mac ${csv}; done;