6

I am looping over the commands with for i in {1..n} loop and want output files to have n extension.

For example: 

 for i in {1..2} do cat FILE > ${i}_output done

However n is user's input:

 echo 'Please enter n' read number for i in {1.."$number"} do commands > ${i}_output done

Loop rolls over n times - this works fine, but my output looks like this {1..n}_output.

How can I name my files in such loop?

Edit

Also tried this 

 for i in {1.."$number"} do k=`echo ${n} | tr -d '}' | cut -d "." -f 3` commands > ${k}_output done

But it's not working.

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1

4 Answers 4

Reset to default
9

Use a "C-style" for-loop:

echo 'Please enter n' read number for ((i = 1; i <= number; i++)) do commands > ${i}_output done

Note that the $ is not required ahead of number or i in the for-loop header but double-parentheses are required.

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Comments

3

The range parameter in for loop works only with constant values. So replace {1..$num} with a value like: {1..10}.

OR

Change the for loop to:

 for((i=1;i<=number;i++))
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2 Comments

i <= number or you'll miss the last element. And you don't need the $ there, either (see my answer).
@Johnsyweb Fixed it. But $ doesn't hurt either :)
0

You can use a simple for loop ( similar to the ones found in langaues like C, C++ etc):

echo 'Please enter n' read number for (( i=1; i <= $number; i++ )) do commands > ${i}_output done
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4 Comments

i <= number. No $.
@Johnsyweb, I tried that out. Seems both are working. :)
Great :-) Every day's a school-day.
Right..I learned something new too. Thanks! :)
-1

Try using seq (1) instead. As in for i in $(seq 1 $number).

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1 Comment

seq involves the execution of an external command that may slow things down, but I'm not sure that warrants a downvote.

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