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What is the easiest way to allow user to enter numbers in following formats so that each individual number can be printed.

comma separated ( 1,5,7 ), space separated ( 1 5 7 ) and range separated ( 1-3,5) 

Expected output if input is comma separated: 
1
5
7
Expected output if input is space separated: 
1
5
7
Expected output if input is - and , separated:
1
2
3
5

I have tried following ways, defining logic only

input_string="1,5,7"
IFS=' ' read -r -a array <<< "$input_string"
echo ${array[1]} etc..

input_string="1 5 7"
 read -r -a array <<< "$input_string"
echo ${array[1]} etc..

Wondering how to handle - and , both together in array , thanks

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3 Answers 3

Reset to default
2

Split on the commas/spaces first, loop over the results, then split on dashes to get a start and an end for the range:

$ cat ranges.sh
#!/bin/bash    
IFS=', ' read -a ranges <<< "$*"
for range in "${ranges[@]}"; do
        IFS=- read start end <<< "$range"
        [ -z "$start" ] && continue
        [ -z "$end" ] && end=$start
        for (( i=start ; i <= end ; i++ )); do
                echo "$i"
        done
done
$ bash ranges.sh 1-3,5 9-10
1       
2               
3       
5
9
10

That could do with better sanity checking etc.

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  • it sounds promising, I tried to use with different input worked well, except trying it with consecutive delimiters adds 0 to output , eg. 1-3,,5 9-10 gives 1 2 3 0 5 9 10.. However as this is not expected in this question and as you mentioned it could do more with some modifications, overall it works well. Commented Aug 20, 2018 at 10:06
  • @Bharat, yeah, that's easy to fix by testing if range or start is empty. But it would also be a good idea to test if start and end are numbers to begin with. Commented Aug 20, 2018 at 10:12
2

Try also

T="$@"
echo {1..100} | { cut -d" " -f"${T// /,}"; }
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  • impressing, it works well as least for this input. Commented Aug 20, 2018 at 10:47
  • 1
    Print all the numbers and let cut pick the ones you want? That's has a bit of a Rube Goldberg smell into it, but at least cut does sanity checking for the arguments! I can't decide between an upvote for creativity, or a downvote for insanity. Commented Aug 20, 2018 at 11:45
2

Came up with an Awk Variant

awk -v RS='[[:blank:]]|[\n]|[,]' '{max=a[split($0, a ,"-")]; if(max!=0){while(a[1]<=max){print a[1]++}}}' /tmp/a.txt

Reading delimited input as a Record, Splitting it into an array using "-" Records without "-" are stored on first index Finally printing values.

Input:

1-3,5 6

Output:

1
2
3
5
6
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