# delete newlines

printf "a\nb\nc\nd\ne\nf" | sed -n -e 'l'
printf "a\nb\nc\nd\ne\nf" | sed -E -e :a -e '$!N; s/\n//g; ta'

printf "a\n\nb" | sed -n -e 'l'
printf "a\n\nb" | sed -E -e :a -e '$!N; s/\n//g; ta' | sed -n -e 'l'
printf "a\n\nb" | sed -E -e :a -e '$!N; s/\n$//g; ta' | sed -n -e 'l'
printf "a\n\n\n\n\n\nb" | sed -E -e :a -e '$!N; s/\n$//g; ta' | sed -n -e 'l'


# delete carriage returns

printf "he\r\rllo\n" | sed -n -e 'l'
printf "he\r\rllo\n" | sed -e s/$'\r'//g | sed -n -e 'l'
printf "he\r\rllo\n" | sed -e s/$'\r\r'/$'\r'/g | sed -n -e 'l'

CR=$'\r'
printf "hello\r\r\n" | sed "s/$CR$CR$/$CR/g" | sed -n -e 'l'


# alternatives

printf "a\nb\nc\nd\ne\nf" | tr -d '\n'

# cf. http://linux.dsplabs.com.au/rmnl-remove-new-line-characters-tr-awk-perl-sed-c-cpp-bash-python-xargs-ghc-ghci-haskell-sam-ssam-p65/
while read -d $'\n'; do echo -n "${REPLY} "; done < <((printf "a\nb\nc\nd\ne\nf"))
while read -d $'\n'; do printf "%s   " "${REPLY}"; done < <((printf "a\nb\nc\nd\ne\nf"))

xargs echo < <((printf "a\nb\nc\nd\ne\nf"))
xargs printf "%s " < <((printf "a\nb\nc\nd\ne\nf"))

printf "a\nb\nc\nd\ne\nf" | /usr/bin/paste -s -d ' ' -     # cf. man paste

# delete newlines in-place (also see below)
vim -e -s +':%j' +'w!' +'qa!' /path/to/file

# insert newlines again
printf "%s\n" "hello" | sed -e s/l/$'\\\n'/g | sed -n -e 'l'
printf "%s\n" "hello" | sed -E s/\(l\)/\\1$'\\\n'/g | sed -n -e 'l'


#-----------------------------------------------------------


# converting between \n and \n\r

# cf. also flip, http://ccrma.stanford.edu/~craig/utility/flip/ and 
# http://codesnippets.joyent.com/posts/show/1660


# convert \n into \r\n
printf "a\nb\nc\nd\ne\nf\n"
printf "a\nb\nc\nd\ne\nf\n" | sed -n -e 'l'

printf "a\nb\nc\nd\ne\nf\n" | sed s/$/$'\r'/
printf "a\nb\nc\nd\ne\nf\n" | sed s/$/$'\r'/ | sed -n -e 'l'

printf "a\nb\n\n\n\n\n\n\n\n\n\n\nc\nd\ne\nf\n" | sed -E -e :a -e '$!N; s/\n$//g; ta' | sed -E s/$/$'\r'/ | sed -n -e 'l'

while read -d $'\n'; do printf "%s\r\n" "${REPLY}"; done < <((printf "a\nb\nc\nd\ne\nf\n"))
while read -d $'\n'; do printf "%s\r\n" "${REPLY}"; done < <((printf "a\nb\nc\nd\ne\nf\n")) | sed -n -e 'l'


# convert \r\n into \n
printf "a\r\nb\r\nc\r\nd\r\ne\r\nf\r\n"
printf "a\r\nb\r\nc\r\nd\r\ne\r\nf\r\n" | sed -n -e 'l'

printf "a\r\nb\r\nc\r\nd\r\ne\r\nf\r\n" | sed s/$'\r'$//
printf "a\r\nb\r\nc\r\nd\r\ne\r\nf\r\n" | sed s/$'\r'$// | sed -n -e 'l'

printf "a\r\nb\r\r\r\r\r\r\r\r\r\r\nc\r\nd\r\ne\r\nf\r\n" | sed s/$'\r'*$// | sed -n -e 'l'
printf "a\r\nb\r\r\r\r\r\r\r\r\r\r\nc\r\nd\r\ne\r\nf\r\n" | sed -E s/$'\r'+$// | sed -n -e 'l'

# lacks a terminating \n though
while read -d $'\r'; do printf "%s" "${REPLY}"; done < <((printf "a\r\nb\r\nc\r\nd\r\ne\r\nf\r\n"))
while read -d $'\r'; do printf "%s" "${REPLY}"; done < <((printf "a\r\nb\r\nc\r\nd\r\ne\r\nf\r\n")) | sed -n -e 'l'


#---------------------------------------


# create test files

testfile="${HOME}/Desktop/testfile.txt"
output="${HOME}/Desktop/output.txt"

function createfiles() {

testfile="${HOME}/Desktop/testfile.txt"
output="${HOME}/Desktop/output.txt"

/usr/bin/touch "$output"

#/usr/bin/jot -b 'sample text' 10 | /bin/cat > "$testfile"
/usr/bin/jot -b 'sample text' 10 | /bin/cat -n > "$testfile"
printf "%s\r\n\r\n\r\r\n" "sample text" >> "$testfile"      # append a line with a '\r\n' line separator
printf "%s" "sample text" >> "$testfile"          # append a last line without a terminating '\n'

return 0
}

createfiles


# inspect test file

cat -vet "$testfile"
ed -s "$testfile" <<< $',l'
sed -n -e 'l'  "$testfile"
ruby -n -e 'p $_.to_s' < "$testfile"


function odcfile() {

/usr/bin/od -A n -c < "$@" | /usr/bin/sed -E -e 's/^[[:space:]]{11}//' \
       -e s/[[:space:]]{4}/$'\001'/g \
       -e 's/[[:space:]]+//g' | \
       /usr/bin/tr -d '\n' | /usr/bin/tr '\001' ' ' | \
       /usr/bin/sed -e s/\\\\n/$'\\\\\\n\\\n'/g 

return 0
}


odcfile "$testfile"


# remove newlines "\n"

# create a new file with newline characters replaced with a space
sed -e :a -e '$!N; s/\n/ /g; ta' "$testfile" > "$output"
odcfile "$output"

# same, but in-place
sed -i "" -e :a -e '$!N; s/\n/ /g; ta' "$testfile"
odcfile "$testfile"

createfiles

# delete newlines in-place
sed -i "" -e :a -e '$!N; s/\n//g; ta' "$testfile"
odcfile "$testfile"

createfiles

# alternative for creating a new file without newlines
tr -d '\n' < "$testfile" > "$output"
odcfile "$output"



# delete carriage returns "\r"

# create a new file with carriage returns deleted
sed -e s/$'\r'//g "$testfile" > "$output"
sed -e s/$'\r'$//g "$testfile" > "$output"  # only at line end
odcfile "$output"

# alternative
tr -d '\r' < "$testfile" > "$output"
odcfile "$output"


# delete carriage returns in-place

sed -i "" -e s/$'\r'//g "$testfile" > "$output"
odcfile "$testfile"

createfiles

# cf. http://bash-hackers.org/wiki/doku.php?id=howto:edit-ed (Pitfalls)
ed -s "$testfile" <<< $'H\n,g/\r/s/\r//\n,w'      # delete one carriage return in a line
ed -s "$testfile" <<< $'H\n,g/\r/s/\r//g\n,w'     # delete all carriage returns in a line
ed -s "$testfile" <<< $'H\n,g/\r$/s/\r$//g\n,w'   # delete a carriage return at line end

odcfile "$testfile"



printf "\n" | od -A n -c
printf "\012" | od -A n -c
printf "\x0a" | od -A n -c

printf '[ctrl-v][ctrl-j]' | od -A n -c      #  \n or ^J


printf "\r" | od -A n -c
printf "\015" | od -A n -c
printf "\x0d" | od -A n -c

printf '[ctrl-v][ctrl-j]' | od -A n -c      #  \r or ^M


# vim
createfiles

vim "$testfile"
#...
:set number
:set list
:%s/^M//g
:set fileformat=unix
#:set fileformat=dos
:x

odcfile "$testfile"


# edit files in-place with vim

createfiles

# delete newlines in-place
vim -e -s +':%j' +'w!' +'qa!' "$testfile"
odcfile "$output"

createfiles

# replace every \r with \n
# cf. http://vim.wikia.com/wiki/Change_end-of-line_format_for_dos-mac-unix
vim -e -s +':%s/\r/\r/g' +':set fileformat=unix' +'w!' +'qa!' "$testfile"
odcfile "$output"

createfiles

# delete every \r
vim -e -s +':%s/\r//g' +':set fileformat=unix' +'w!' +'qa!' "$testfile"
odcfile "$output"

createfiles

# delete \r only when it occurs at the end of a line
vim -e -s +':%s/\r$//g' +':set fileformat=unix' +'w!' +'qa!' "$testfile"
odcfile "$output"

createfiles

# replace carriage return line endings with \n
# cf. Getting rid of ^M - mixing dos and unix, http://www.vim.org/tips/tip.php?tip_id=26
printf "\r" >> "$testfile"
vim -e -s +':g/\r$/s///g' +':set fileformat=unix' +'w!' +'qa!' "$testfile"
odcfile "$testfile"

createfiles

# delete last \n of file
vim -e -s +':set noeol bin' +':set fileformat=unix' +'w!' +'qa!' "$testfile"
odcfile "$output"

createfiles

# change mixed mode files to DOS mode
#vim -e -s +':%s/\r\r/\r/g' +'w!' +'qa!' "$testfile"
sed -i '' -e s/$'\r\r'/$'\r'/g  "$testfile"
vim -e -s +':e ++ff=dos' +'w!' +'qa!' "$testfile"
vim -e -s +':e ++ff=dos' +':set ff=dos' +'w!' +'qa!' "$testfile"
odcfile "$output"

vim "$testfile"
:set ff?
:x