Shell Programming and Scripting

#!/bin/bash --posix
# num.sh
# Create a null file for fullness IF you want to...
# > /tmp/kuku.txt
data="2013102100"
data1="${data:0:4}"
data2="${data:4:2}"
data3="${data:6:2}"
data4="${data:8:2}"
echo "$data1 $data2 $data3 $data4"
# Notice spaces are now removed as per your EDIT!!!
echo "$data1$data2$data3$data4" > /tmp/kuku.txt
cat < /tmp/kuku.txt
#for n in {1..99}
#do
#	data4="0$n"
#	echo "$data1 $data2 $data3 $data4"
#	echo "$data1$data2$data3$data4" > /tmp/kuku.txt
#	cat < /tmp/kuku.txt
#done
data4="04"
echo "$data1 $data2 $data3 $data4"
echo "$data1$data2$data3$data4" > /tmp/kuku.txt
cat < /tmp/kuku.txt
data4="100"
echo "$data1 $data2 $data3 $data4"
echo "$data1$data2$data3$data4" > /tmp/kuku.txt
cat < /tmp/kuku.txt

Last login: Thu Oct 10 19:35:31 on ttys000
AMIGA:barrywalker~> ./num.sh
2013 10 21 00
2013102100
2013 10 21 04
2013102104
2013 10 21 100
20131021100
AMIGA:barrywalker~>

n= sort /Users/Natalie/1/kuku.txt | tail -1
#n=2013080805
#echo "${n:0:4} ${n:4:2} ${n:6:2} ${n:8:2}"

fourthoct=${n:0:4}
thirdoct=${n:4:2}
secondoct=${n:6:2}
firstoct=${n:8:2}
echo $n


            if [ $((++firstoct)) -eq 101 ]
                   then
                  firstoct=00
                   if [ $((++secondoct)) -eq 32 ]
                        then

                        secondoct=0
                         if [ $((++thirdoct)) -eq 13 ]
                               then
                                thirdoct=0
                                   ((++fourthoct))
fi
fi
fi

echo $fourthoct$thirdoct$secondoct$firstoct

$ cat kuku.txt
2013101005
$ sh increm $(cat kuku.txt)
2013101006
$

echo $fourthoct 
echo $thirdoct 
echo $secondoct 
echo $firstoct

2013080805

201308086

$ i=6
$ echo $i
6
$ printf '%02d\n' $i
06
$

n=$(sort /Users/Natalie/1/kuku.txt | tail -1)
echo $n
exit