printf shell command

[Wouter Jagers]

Hi all,

I just bounced into something strange. Can anyone explain the below ?

------------------------------
..
$ printf "%02d\n" 05
05
$ printf "%02d\n" 06
06
$ printf "%02d\n" 07
07
$ printf "%02d\n" 08
printf: Error converting 08
00
$ printf "%02d\n" 09
printf: Error converting 09
00
$ printf "%02d\n" 10
10
$ printf "%02d\n" 8
08
$ printf "%02d\n" 9
09
------------------------------

As you can see, for some reason printf doesn't like 08 or 09, but acts as expected for the others.. 8 and 9 (without the leading zero) also seems ok.

Is this fishy, or is it monday again and am I missing something blatantly obvious ?

Cheers
Wout

[Peter Godron · Accepted solution]

Wout,
By prefixing with zero the value is read as octal.
Try printf "%02d\n" 012 and you get 10, which is 8+2

[Wouter Jagers]

Isn't that %o (o, not zero) ?

---
$ printf "%02d\n" 10
10
$ printf "%o\n" 10
12
---

The plan is to convert any one or two digit integer to a two digit one, leading zero if applicable.

I could use sed just as well, but I'm intrigued about my 'issue' ;-)

[Wouter Jagers]

Ohhhh, I see. Sorry about that last one.
It is monday for sure :-p

Thanks !

[Peter Godron]

Wout,
your code is right, just don't pass the leading zero as input!

printf "%02d\n" 1 => 01
printf "%02d\n" 9 => 09
printf "%02d\n" 10 => 10
etc.

[Peter Nikitka]

Hi,

you mix input- and output specifications:
The %-specifier is an output directive - you specify this.
For the input, the printf knows nothing about a typedef or so - it just sees a string. This string - the 08 - is scanned heuristically for a valid input specification. The convention is now, e.g.
0N - octal number N
0xNN - hex number NN

Any "violation" will be reported; the diagnostic output will differ between implementations of printf (e.g. printf: 08 not completely converted.).

To get your requested output format, use:
typeset -Z2 j
typeset -i i=0
while [ i -lt 12 ]
do
j=$i
print $j
((i+=1))
done

The output:
00
01
02
03
04
05
06
07
08
09
10
11

mfG Peter

[Wouter Jagers]

Yes, only the thing is my little procedure is accepting day/month fields which can be one or two digits, so "8" and "08" can both come in, depending on input.

I've quickly sed'ded the leading zero away, no problem there.. Thanks for sorting out my confusion, I was really dazzled there for a second :-)

Cheers

[Peter Nikitka]

Hi,

the typeset -Z2 will work for this as well:

typeset -Z2 j=08
print $j
08

mfG Peter

[Wouter Jagers]

All confusion was cleared. Thanks guys !

[Bill Hassell]

And for completeness, old version of the POSIX shell treated leading zeros as decimal so after patching (about 3-4 years ago), some scripts would break (as they should). Octal interpretation was inconsistent in the sh-posix shell. See PHCO_25597 and PHCO_26789.