How do I check for blank fields on a delimited line with sed or awk - bash

Question

I'm parsing source input files using a bash script. I'm generating delimited output in a file. I need a way to check that each field of the delimited output is populated. For example AA,BB,3,4,5,6,7,8 would be good and AA,,3,4,5,6,,8 would be bad. How do I check if there are blank fields on a line using sed/awk or some other tool I can put in a bash script? Thanks in advance!

Answer 1

With bash:
string='AA,,3,4,5,6,,8'
if [[ $string =~ ^,|,,|,$ ]]; then
echo "error"
else
echo "okay"
fi
Output:
error

Answer 2

You can print the lines with at least one empty field using:
awk -F, '{for (i=1;i<=NF;i++) if ($i=="") {print; next}}'
-F, sets the field delimiter as ,
for (i=1;i<=NF;i++) iterates over the fields
if ($i=="") {print; next} prints the record if the field being tested is empty and goes to the next record
Example:
% cat file.txt
AA,BB,3,4,5,6,7,8
AA,,3,4,5,6,,8
% awk -F, '{for (i=1;i<=NF;i++) if ($i=="") {print; next}}' file.txt
AA,,3,4,5,6,,8

Answer 3

You can test with a regular expression with a repeating group that fits with your requirement:
grep -E '^([^,]+,)*[^,]$' <<< "${AA,,3,4,5,6,,8}"
Testcode:
for str in "AA,BB,3,4,5,6,7,8" "AA,,3,4,5,6,,8" ; do
echo "==========="
echo "Testing >>>${str}<<<"
grep -Eq '^([^,]+,)*[^,]$' <<< "${str}" || echo "String incorrect"
done
You can grep the incorrect lines from a file using
grep -vE '^([^,]+,)*[^,]$' inputfile