Question

what would be the sed (or other tool) command to join lines together in a file that do not end w/ the character ‘0’?

I’ll have lines like this

412|n|Leader Building Material||||||||||d|d|20||0

which need to be left alone, and then I’ll have lines like this for example (which is 3 lines, but only one ends w/ 0)

107|n|Knot Tying Tools|||||Knot Tying Tools

|||||d|d|0||0

which need to be joined/combined into one line

107|n|Knot Tying Tools|||||Knot Tying Tools|||||d|d|0||0

Answer 1

 sed ':a;/0$/{N;s/\n//;ba}'

In a loop (branch ba to label :a), if the current line ends in 0 (/0$/) append next line (N) and remove inner newline (s/\n//).

awk:

awk '{while(/0$/) { getline a; $0=$0 a; sub(/\n/,_) }; print}'

Perl:

perl -pe '$_.=<>,s/\n// while /0$/'

bash:

while read line; do 
    if [ ${line: -1:1} != "0" ] ; then 
        echo $line
    else echo -n $line
fi
done