I am trying to make a while loop that goes through a text file line by line, tests whether a field is blank using Awk, then does an action based on whether that condition is true or false.
The input file is this:
$ cat testarr.csv
cilantro,lamb,oranges
basil,,pears
sage,chicken,apples
oregano,,bananas
tumeric,turkey,plums
pepper,,guavas
allspice,goose,mangos
My expected output is:
this_is_one_iteration
ItIsNotBlank
this_is_one_iteration
ItIsBlank
this_is_one_iteration
ItIsNotBlank
this_is_one_iteration
ItIsBlank
this_is_one_iteration
ItIsNotBlank
this_is_one_iteration
ItIsBlank
this_is_one_iteration
ItIsNotBlank
based on Using 'if' within a 'while' loop in Bash and similar threads, I did this:
#!/bin/bash
error=ItIsBlank
success=ItIsNotBlank
while read LINE; do
echo this_is_one_iteration
QZ1=$(awk -F "," '{print (!$2)}')
if [[ $QZ1==0 ]] ; then
echo $error
else
echo $success
fi
done < testarr.csv
which gave me:
$ bash testloop.sh
this_is_one_iteration
ItIsBlank
So it doesn't even seem to be iterating through the file. However, if I take out the conditional, it iterates just fine.
#!/bin/bash
error=ItIsBlank
success=ItIsNotBlank
while read LINE; do
echo this_is_one_iteration
done < testarr.csv
gives:
$ bash testloop.sh
this_is_one_iteration
this_is_one_iteration
this_is_one_iteration
this_is_one_iteration
this_is_one_iteration
this_is_one_iteration
this_is_one_iteration
also, the conditional seems to work OK when not using awk:
QZ1=test
while read LINE; do
echo this_is_one_iteration
if [[ $QZ1=="test" ]] ; then
echo It_worked
fi
done < testarr.csv
Gives me:
$ bash testloop.sh
this_is_one_iteration
It_worked
this_is_one_iteration
It_worked
this_is_one_iteration
It_worked
this_is_one_iteration
It_worked
this_is_one_iteration
It_worked
this_is_one_iteration
It_worked
this_is_one_iteration
It_worked
Your script is correct except for a minor error. Add echo $LINE and pipe it to the awk statement. Awk in your script has no input to work on.
#!/bin/bash
error=ItIsBlank
success=ItIsNotBlank
while read LINE; do
echo this_is_one_iteration
QZ1=$(echo $LINE|awk -F "," '{print (!$2)}')
if [[ $QZ1 -eq 0 ]] ; then
echo $error
else
echo $success
fi
done < testarr.csv
When i run the script now:
[ec2-user@ip check]$ ./script.sh
this_is_one_iteration
ItIsBlank
this_is_one_iteration
ItIsBlank
this_is_one_iteration
ItIsBlank
this_is_one_iteration
ItIsBlank
this_is_one_iteration
ItIsBlank
this_is_one_iteration
ItIsBlank
this_is_one_iteration
ItIsBlank
Hope this resolves your issue.
tests whether a field is blank using Awk
I suppose, it can be achieved with single awk process:
awk -F, '{ print "this_is_one_iteration"; f="Not";
for(i=1;i<=NF;i++) if($i=="") { f="";break }; printf "ItIs%sBlank\n",f }' testarr.csv
The output:
this_is_one_iteration
ItIsNotBlank
this_is_one_iteration
ItIsBlank
this_is_one_iteration
ItIsNotBlank
this_is_one_iteration
ItIsBlank
this_is_one_iteration
ItIsNotBlank
this_is_one_iteration
ItIsBlank
this_is_one_iteration
ItIsNotBlank
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