Bash code for Selecting few columns from a variable - awk

Question

In a file I have a list of coordinates stored (see figure, to the left).
From there I want to copy the coordinates only (red marked) and put them in another file.
I copy the correct section from the file using COORD=`grep -B${i} '&END COORD' ${cpki_file}. Then I tried to use awk to extract the required numbers from the COORD variable . It does output all the numbers in the file but deletes the spaces between values (figure, to the right).
How to write the red marked section as they are?
N=200
NEndCoord=`grep -B${N} '&END COORD' ${cpki_file}|wc -l`
NCoord=`grep -B${N} '&END COORD' ${cpki_file}| grep -B200 '&COORD' |wc -l`
let i=$NEndCoord-$NCoord
COORD=`grep -B${i} '&END COORD' ${cpki_file}`
echo "$COORD" | awk '{ print $2 $3 $4 }'
echo "$COORD" | awk '{ print $2 $3 $4 }'>tmp.txt

Answer 1

When you start using combinations of grep, sed, awk, cut and alike, you should realize you can do it all in a single awk command. In case of the OP, this would do exactly the same:
awk '/[&]END COORD/{p=0}
p { print $2,$3,$4 }
/[&]COORD/{p=1}' file
This parses the file keeping track of a printing flag p. The flag is set if "&COORD" is found and unset if "&END COORD" is found. Printing is done, only when the flag p is set. Since we don't want to print the line with "&END COORD", we have to reset the flag before we do the check for the printing. The same holds for the line with "&COORD", but there we have to reset it after we do the check for the printing (its a bit a weird reversed logic).
The problem with the above is that it will also process the lines
UNIT angstrom
If you want to have these removed, you might want to do a check on the total columns:
awk '/[&]END COORD/{p=0}
p && (NF==4){ print $2,$3,$4 }
/[&]COORD/{p=1}' file
Of only print the lines which do not contain "UNIT" or are empty:
awk '/[&]END COORD/{p=0}
p && (NF>0) && ($1 != "UNIT"){ print $2,$3,$4 }
/[&]COORD/{p=1}' file

Answer 2

sed one-liner:
sed -n '/^&COORD$/,/^UNIT/{s/.*[[:space:]]\+\(.*\)[[:space:]]\+\(.*\)[[:space:]]\+\(.*\)/\1\t\2\t\3/p}' <infile.txt >outfile.txt
Explanation:
Invocation:
sed: stream editor
-n: do not print unless eplicit
Commands in sed:
/^&COORD$/,/^UNIT/: Selects groups of lines after &COORDS and before UNIT.
{s/.*[[:space:]]\+\(.*\)[[:space:]]\+\(.*\)[[:space:]]\+\(.*\)/\1\t\2\t\3/p}: Process each selected lines.
s/.*[[:space:]]\+\(.*\)[[:space:]]\+\(.*\)[[:space:]]\+\(.*\): Regex capture space delimited groups except the first.
/\1\t\2\t\3/: Replace with tab delimited values of the captured groups.
p: Explicit printout.