merge tricks

xargs -n2 -d'\n'

paste -s -d ',\n' infile

paste -d " "  - - < filename

awk 'NR%2{printf "%s ",$0;next;}1' yourFile

awk '{key=$0; getline; print key ", " $0;}'

awk 'ORS=NR%2?FS:RS' file

awk 'ORS=NR%2?FS:RS' file

```sh
awk '{ ORS = (NR%2 ? FS : RS) } 1' file

awk '{ ORS = (NR%2 ? "," : RS) } 1' file

awk '{ if (NR%2 != 0) line=$0; else {printf("%s %s\n", line, $0); line="";} } END {if (length(line)) print line;}'

sed 'N;s/\n/ /' yourFile

while read line1; do read line2; echo "$line1, $line2"; done < data.txt

ex -c "%g/KEY/j" -c "wq" data.txt

perl -0pe 's/(.*)\n(.*)\n/$1 $2\n/g'