Expand variable in brace expansion

Question

I am trying to enumerate a range of integers using a variable but having some trouble. When I type

echo {1..5}

I get

1 2 3 4 5

However, when I type a variable, I am unable to get the enumeration. For example

$ num=5
$ echo {1..$num}
{1..5}

I am stumped as to why the result is not the same. I have tried using quotes and that has not helped either. Can someone help or explain?

Brace expansion happens before variable expansion in bash... — jasonwryan, Apr 23 '15 at 03:24
You could use eval, but there are probably cleaner solutions. — jasonwryan, Apr 23 '15 at 03:27

score 3 · Accepted Answer · edited Apr 23 '15 at 03:34

3

You may use this:

 num=5;
 echo $(seq $num)

Gives:

 1 2 3 4 5

Remark: $(...) syntax is command substitution.

edited Apr 23 '15 at 03:34

jasonwryan

answered Apr 23 '15 at 03:32

Johnny Wong

5

Or just seq -s " " $num, thus avoiding echo and subshell expansion. – Janis Apr 23 '15 at 03:56

1 Answers1