Joining every group of N lines into one with bash

Question

I would like to join every group of N lines in the output of another command using bash.

Are there any standard linux commands i can use to achieve this?

Exa

Answer 1

Seems like you're trying to join every two lines with the delimiter \t(tab). If yes then you could try the below paste command,

command | paste -d'\t' - -

If you want space as delimiter then use -d<space>,

command | paste -d' ' - -

Answer 2

If your output has consistent number of fields, you can use xargs -n N to group on X elements per line:

$ ...command... | xargs -n4
46.219464 0.000993 17.951781 0.002545
15.770583 0.002873 87.431820 0.000664
97.380751 0.001921 25.338819 0.007437

From man xargs:

-n max-args, --max-args=max-args

Use at most max-args arguments per command line. Fewer than max-args arguments will be used if the size (see the -s option) is exceeded, unless the -x option is given, in which case xargs will exit.