I am trying to create a nested for loop which will count from 1 to 10 and the second or nested loop will count from 1 to 5.
for ((i=1;i<11;i++));
do
for ((a=1;a<6;a++));
do
echo $i:$a
done
done
What I though the output of this loop was going to be was:
1:1
2:2
3:3
4:4
5:5
6:1
7:2
8:3
9:4
10:5
But instead the output was
1:1
1:2
1:3
1:4
1:5
2:1
...
2:5
3:1
...
and same thing till 10:5
How can I modify my loop to get the result I want! Thanks
Your logic is wrong. You don't want a nested loop at all. Try this:
for ((i=1;i<11;++i)); do
echo "$i:$((i-5*((i-1)/5)))"
done
This uses integer division to subtract the right number of multiples of 5 from the value of $i:
$i is between 1 and 5, (i-1)/5 is 0, so nothing is subtracted$i is between 6 and 10, (i-1)/5 is 1, so 5 is subtractedetc.
You must not use a nested loop in this case. What you have is a second co-variable, i.e. something that increments similar to the outer loop variable. It's not at all independent of the outer loop variable.
That means you can calculate the value of a from i:
for ((i=1;i<11;i++)); do
((a=((i-1)%5)+1))
echo $i:$a
done
%5 will make sure that the value is always between 0 and 4. That means we need i to run from 0 to 9 which gives us i-1. Afterwards, we need to move 0...4 to 0...5 with +1.
I know @AaronDigulla's answer is what OP wants. this is another way to get the output :)
paste -d':' <(seq 10) <(seq 5;seq 5)
a=0
for ((i=1;i<11;i++))
do
a=$((a%5))
((a++))
echo $i:$a
done
If you really need it to use 2 loops, try
for ((i=1;i<3;i++))
do
for ((a=1;a<6;a++))
do
echo "$((i*a)):$a"
done
done
a=$((i%5)). Either way, the output is incorrect!
echo {1..5}{1..5}.