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From: Hongyi Zhao on 1 Feb 2010 02:12
Hi all,

I want to do the following simple addition operations under bash by
using expr:

1- I've two variables, i.e., aa and bb.

2- If the addition of aa + bb is little than 10, it should give me
the output with a leading zero like this: 01, 08, 09 or so.

3- If the addition of aa + bb is large than 10, it should give me the
output without a leading zero.

What should I do?

Thanks in advance.
--
..: Hongyi Zhao [ hongyi.zhao AT gmail.com ] Free as in Freedom :.
From: Sidney Lambe on 1 Feb 2010 02:36
On comp.unix.shell, Hongyi Zhao <hongyi.zhao(a)gmail.com> wrote:
> Hi all,
>
> I want to do the following simple addition operations under bash by
> using expr:
>
> 1- I've two variables, i.e., aa and bb.
>
> 2- If the addition of aa + bb is little than 10, it should give me
> the output with a leading zero like this: 01, 08, 09 or so.
>
> 3- If the addition of aa + bb is large than 10, it should give me the
> output without a leading zero.
>
> What should I do?
>
> Thanks in advance.

Bash:

(( $aa + $bb = cc }}

if [ "$cc" -lt 10 ]

then cc=$(echo "$cc" | sed 's/.*/0&/')

fi


There are surely better ways to do it.


Sid


From: Mart Frauenlob on 1 Feb 2010 02:43
On 01.02.2010 08:12, Hongyi Zhao wrote:
> Hi all,
>
> I want to do the following simple addition operations under bash by
> using expr:
>
> 1- I've two variables, i.e., aa and bb.
>
> 2- If the addition of aa + bb is little than 10, it should give me
> the output with a leading zero like this: 01, 08, 09 or so.
>
> 3- If the addition of aa + bb is large than 10, it should give me the
> output without a leading zero.
>
> What should I do?
>
> Thanks in advance.


eris:~# a=3
eris:~# printf "%02d\n" "$a"
03
eris:~# a=33
eris:~# printf "%02d\n" "$a"
33



From: Sidney Lambe on 1 Feb 2010 03:11
On comp.unix.shell, Mart Frauenlob <mart.frauenlob(a)chello.at>
wrote:

> On 01.02.2010 08:12, Hongyi Zhao wrote:
>
>> Hi all,
>>
>> I want to do the following simple addition operations under
>> bash by using expr:
>>
>> 1- I've two variables, i.e., aa and bb.
>>
>> 2- If the addition of aa + bb is little than 10, it should
>> give me the output with a leading zero like this: 01, 08, 09
>> or so.
>>
>> 3- If the addition of aa + bb is large than 10, it should give
>> me the output without a leading zero.
>>
>> What should I do?
>>
>> Thanks in advance.
>

>
> eris:~# a=3
> eris:~# printf "%02d\n" "$a"
> 03
> eris:~# a=33
> eris:~# printf "%02d\n" "$a"
> 33
>
>
>

Very slick.

I'm reading man printf and sprintf in an attempt to
understand what you've done there, but it isn't coming
easy. Are you a C programmer by any chance?


Sid


From: Sidney Lambe on 1 Feb 2010 03:16
On comp.unix.shell, Mart Frauenlob <mart.frauenlob(a)chello.at> wrote:
> On 01.02.2010 08:12, Hongyi Zhao wrote:
>> Hi all,
>>
>> I want to do the following simple addition operations under bash by
>> using expr:
>>
>> 1- I've two variables, i.e., aa and bb.
>>
>> 2- If the addition of aa + bb is little than 10, it should give me
>> the output with a leading zero like this: 01, 08, 09 or so.
>>
>> 3- If the addition of aa + bb is large than 10, it should give me the
>> output without a leading zero.
>>
>> What should I do?
>>
>> Thanks in advance.
>
>
> eris:~# a=3
> eris:~# printf "%02d\n" "$a"
> 03
> eris:~# a=33
> eris:~# printf "%02d\n" "$a"
> 33
>
>
>


Okay, I think I've got it. But what if a=333?

Sid

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