Shell Programming and Scripting

a = test1
b =  test2
a = test3
b= test4
c = test6
b = test5
d = test7
d = test9

a = test1,test3
b = test2, test5
c = test6
d = test7, test9

awk '
        {gsub(/ /,"")
         T[$1]=T[$1] DL[$1] $2
         DL[$1]=","
        }
END     {for (t in T) print t " = " T[t]
        }
' FS="="  file
a = test1,test3
b = test2,test4,test5
c = test6
d = test7,test9

awk -F" *= *" '{A[$1]=A[$1]?A[$1] OFS $NF:$NF} END{for(i in A){print i " = " A[i]}}' OFS=,  Input_file

a = test1,test3
b = test2,test4,test5
c = test6
d = test7,test9

perl -nlaF'/\s*=\s*/' -e 'push @{$seen{$F[0]}}, $F[1]; END{$"=q{,};for $k (sort keys %seen){print "$k = @{$seen{$k}}"}}' iron_michael86.file
a = test1,test3
b = test2,test4,test5
c = test6
d = test7,test9

perl -nlaF'/\s*=/' -e 'push @{$seen{$F[0]}}, $F[1]; END{$"=q{,};for $k (sort keys %seen){print "$k = @{$seen{$k}}"}}' iron_michael86.file 
a =  test1, test3
b =   test2, test4, test5
c =  test6
d =  test7, test9