Creating a range of numbers from 08 to 10 in bash doesn't include 0 in front of one digit numbers

Question

On my local machine, where I run CentOS 7.2, when I do this:

for i in {8..12}; do echo ${i}; done

I got:

8
9
10

But when I do this:

for i in {08..10}; do echo ${i}; done

I got:

08
09
10

But on server to which I have access, which runs CentOS 5.6, running both commands results in the same output:

8
9
10

Why there are no zeroes in front of 8 and 9? Is it because of bash version, or just environment configuration? Can I change it per session or permanently, so my server will put that zero in front of numbers smaller than 10?

Brace expansion with zero-filling was introduced in Bash 4. Your CentOS installation may use Bash 3? — Kusalananda, Apr 07 '17 at 06:31
Related: http://unix.stackexchange.com/questions/60257/how-to-create-a-sequence-with-leading-zeroes-using-brace-expansion — Kusalananda, Apr 07 '17 at 06:31
@Kusalananda: yes, you were right. I didn't noticed your answer before. — Learner, Apr 07 '17 at 12:42

Kusalananda · Accepted Answer · 2017-04-12T09:13:04.490

3

It's probable that the bash on your CentOS 5.6 machine is version 3. Zero-filling of integers in brace expansions was introduced in version 4 of bash.

The solution would be to either update your installation of bash to a more recent version, or to use an alternative way of generating the zero-filled integers, like

printf '%02d\n' {8..10}

Alternatively, something along the lines of

for i in 0{1..9} {10..20}; do
    echo "$i"
done

will also work.

edited Apr 12 '17 at 09:13

answered Apr 07 '17 at 07:24

Kusalananda

320,670
36
633
936

Yes, you are right. Bash on my CentOS 7.2 is 4.x version, and bash on that server which I mentioned is 3.x version. I am marking this as a solution since I mostly wanted to learn why is the difference happening. Thanks! – Learner Apr 07 '17 at 07:36

score 2 · Answer 2 · answered Apr 07 '17 at 07:48

2

Instead of using bash, you could use zsh where that syntax comes from.

zsh has been supporting {08..10} since 1995 (introduced in 2.6-beta4), so will be available in the zsh of any version of CentOS (first release of CentOS in 2004).

You did actually use zsh syntax in your example as in bash you need echo "${i}" instead of echo ${i} for the expansion of $i not to be subject to word splitting (and so dependant on $IFS).

answered Apr 07 '17 at 07:48

Stéphane Chazelas

522,931
91
1,010
1,501

Thanks, that's good to know. I wasn't aware that it comes from zsh. – Learner Apr 07 '17 at 10:44
@Learner, most `bash` features come from `ksh`, a few from `csh`/`tcsh` like history expansion, and a few from `zsh`. It has very few of its own. – Stéphane Chazelas Apr 07 '17 at 11:23

score 1 · Answer 3 · edited Apr 07 '17 at 09:36

1

alternative, you can use seq command

$ seq -f "%02g" 8 10
08
09
10

edited Apr 07 '17 at 09:36

Kusalananda

320,670
36
633
936

answered Apr 07 '17 at 07:32

Kamaraj

4,295
1
12
18

Creating a range of numbers from 08 to 10 in bash doesn't include 0 in front of one digit numbers

3 Answers3

Linked

Related