Shell Programming and Scripting

awk -F, '
val && /^[0-9]+/ && val !~ $0{
    print val;
    for(i in b){
       if(a[i]){
         print c[i],a[i];
         delete a[i]
};
       print b[i]
};
    delete b;
    delete c
}
/^[0-9]+/{
    val=$0;
    next
}
{
    c[$1]=$1 FS $2;
    a[$1]+=$3;
    b[$1]=b[$1]?b[$1] ORS $0:$0
}
END{
    print val;
    for(i in b){
       if(a[i]){
         print c[i],a[i];
         delete a[i]
};
    print b[i]
}
}
'   Input_file

20170308
PM,U 246
PM,I,123
PM,U,123
DA,U 135
DA,I,113
DA,U,22
20170309
PM,U 256
PM,I,23
PM,U,233
DA,U 134
DA,I,11
DA,U,123

20170308
PM,U 246
PM,U, 113
PM,I,123
PM,U,123
DA,U 135
DA,I,113
DA,U,22