bash/sed/awk/etc remove every other newline

can't test right now, but

... | paste - - 

should do it

One possibility is:

awk 'ORS=NR%2?" ":"\n"'

If the line number is evenly divisible by 2, end with a new line, otherwise, end with a space.

(Tested on: CentOS 6, GNU Awk 3.1.7)

Using sed (see explanation):

sed ':a;N;$!ba;s/\nGroup/ Group/g'

Further reading:

• Removing new line characters

If you want to use sed, there's no reason to read the whole file into memory. You can merge every other line like this:

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

Use any character you'd like instead of the space.

Here's another way using awk:

awk '{printf "%s", $0; if (getline) print " " $0; else printf "\n"}' inputfile

The if/else handles the case where there is an odd number of lines in the file. Without it, the odd last line gets printed twice. Otherwise, for comparison, you could do:

awk '{printf "%s", $0; getline; print " " $0}'

This works for me on Linux:

... | tr "\\n" " "

This replaces an empty space for a newline character; you must escape the newline character for things to work correctly.