I know how to transpose rows in a file to columns, but I want to append the lines of the bottom half of a file to the lines to the upper half.
Like:
A1
A2
A3
B1
B2
B3
to
A1 | B1
A2 | B2
A3 | B3
the list comes from two greps. I append the first grep with the second one. The two greps have the same amount of hits.
I want to do this within a bash script.
What about combining head and tail together with paste?
paste -d'|' <(head -3 file) <(tail -3 file)
It returns:
A1|B1
A2|B2
A3|B3
paste merges lines of files. If we provide different lines from the same file... that's all!
As it is a matter of getting head from the half of the lines and tail from the rest, this is a more generic way:
paste -d'|' <(head -n $(($(wc -l <file)/2)) file)
<(tail -n $(($(wc -l <file)/2)) file)
You're looking for the pr tool:
printf "%s\n" {A,B}{1,2,3} | pr -2 -T -s" | "
A1 | B1
A2 | B2
A3 | B3
pr -2 -T -s" | " -> pr: illegal option -- T and pr -2 -s" | " -> pr: illegal option -- |. Is this GNU pr or something?$ awk '{a[NR]=$0} END{ m=NR/2; for (i=1;i<=m;i++) print a[i] " | " a[i+m]}' file
A1 | B1
A2 | B2
A3 | B3
Just as an alternative:
awk 'BEGIN{c=0}
{a[c++] = $1}
END { for (i = 0; i < c/2; i++) print a[i] " " a[i+c/2]}'
This assumes you have an even number of lines as input.
greps, etc, so that we can provide better answers. Also, what did you try so far?