Shell Programming and Scripting

i/p=aaaabbcaa
length=${#i/p} 

for (i=0;i<$length;i++)
do
tmp=""
character=${ip:"$i"}
	if [[ $character != $tmp ]]
	then
	o/p=$character
	tmp=$character
	else
	o/p=$character$i
	fi
done

awk  '
        {LAST = $1
         CNT = 0
         for (i=1; i<=NF; i++)  {if ($i == LAST) CNT++
                                 else           {printf "%s%d", LAST, CNT
                                                 CNT = 1
                                                }
                                 LAST = $i
                                }
         printf "%s%d\n", LAST, CNT
        }
' FS="" file
a4b2c1a2

echo aaaabbcaa | fold -w 1 | uniq -c | awk '{l=l$2$1} END {print l}'

ip=aaaabbcaa

for((i=0; i<${#ip}; i++))
do
    ((found++))
    character=${ip:i:1}
    nextchar=${ip:i+1:1}
    if [[ $character != $nextchar ]]
    then
        op=$op$character$found
        found=0
    fi
done
echo $op

ip="aaaabbcaa"
op=$(echo "$ip" | awk '{while (/./) {c=substr($0, 1, 1); match($0, c "*", a); printf c RLENGTH; sub(a[0], "")}}')
echo "$op"