issue for condition on unique raws in bash - bash

Question

I want to print rows of a table in a file, the issue is when I use a readline the reprint me the result several times, here is my input file
aa ,DEC ,file1.txt
aa ,CHAR ,file1.txt
cc ,CHAR ,file1.txt
dd ,DEC ,file2.txt
bb ,DEC ,file3.txt
bb ,CHAR ,file3.txt
cc ,DEC ,file1.txt
Here is the result I want to have:
printed in file1.txt
aa#DEC,CHAR
cc#CHAR,DEC
printed in file2.txt
dd#DEC
printed in file3.txt
bb#DEC,CHAR
here is it my attempt :
(cat input.txt|while read line
do
table=`echo $line|cut -d"," -f1
variable=`echo $line|cut -d"," -f2
file=`echo $line|cut -d"," -f3
echo ${table}#${variable},
done ) > ${file}

Answer 1

This can be done in a single pass gnu awk like this:
awk -F ' *, *' '{
map[$3][$1] = (map[$3][$1] == "" ? "" : map[$3][$1] ",") $2
}
END {
for (f in map)
for (d in map[f])
print d "#" map[f][d] > f
}' file
This will populate this data:
=== file1.txt ===
aa#DEC,CHAR
cc#CHAR,DEC
=== file2.txt ===
dd#DEC
=== file3.txt ===
bb#DEC,CHAR

Answer 2

With your shown samples, could you please try following, written and tested in shown samples in GNU awk.
awk '
{
sub(/^,/,"",$3)
}
FNR==NR{
sub(/^,/,"",$2)
arr[$1,$3]=(arr[$1,$3]?arr[$1,$3]",":"")$2
next
}
(($1,$3) in arr){
close(outputFile)
outputFile=$3
print $1"#"arr[$1,$3] >> (outputFile)
delete arr[$1,$3]
}
' Input_file Input_file
Explanation: Adding detailed explanation for above.
awk ' ##Starting awk program from here.
{
sub(/^,/,"",$3) ##Substituting starting comma in 3rd field with NULL.
}
FNR==NR{ ##Checking condition FNR==NR will be true when first time Input_file is being read.
sub(/^,/,"",$2) ##Substituting starting comma with NULL in 2nd field.
arr[$1,$3]=(arr[$1,$3]?arr[$1,$3]",":"")$2
##Creating arr with index of 1st and 3rd fields, which has 2nd field as value.
next ##next will skip all further statements from here.
}
(($1,$3) in arr){ ##Checking condition if 1st and 3rd fields are in arr then do following.
close(outputFile) ##Closing output file, to avoid "too many opened files" error.
outputFile=$3 ##Setting outputFile with value of 3rd field.
print $1"#"arr[$1,$3] >> (outputFile)
##printing 1st field # arr value and output it to outputFile here.
delete arr[$1,$3] ##Deleting array element with index of 1st and 3rd field here.
}
' Input_file Input_file ##Mentioning Input_file 2 times here.

Answer 3

You have several errors in your code. You can use the built-in read to split on a comma, and the parentheses are completely unnecessary.
while IFS=, read -r table variable file
do
echo "${table}#${variable}," >>"$file"
done< input.txt
Using $file in a redirect after done is an error; the shell wants to open the file handle to redirect to before file is defined. But as per your requirements, each line should go to a different `file.
Notice also quoting fixes and the omission of the useless cat.
Wrapping fields with the same value onto the same line would be comfortably easy with an Awk postprocessor, but then you might as well do all of this in Awk, as in the other answer you already received.