Hi Jonathan,
I didn't check the POSIX spec, my fault ;-)
So bash chooses to conform to POSIX regarding this behaviour, not bad I believe.
But the help message of printf is somewhat misleading as it says:
$ help printf
printf: printf [-v var] format [arguments]
Formats and prints ARGUMENTS under control of the FORMAT.
[snipped]
In addition to the standard format specifications described in printf(1)
and printf(3), printf interprets:
[snipped]
while printf(3) describes %c as below:
$ man 3 printf
[snipped]
c If no l modifier is present, the int argument is converted to an
unsigned char, and the resulting character is written.
[snipped]
That's why I thought "printf %c 65" should have printed an 'A' instead of
the initial character '6'. I also checked Perl and found what I wanted:
$ perl -e 'printf "%c\n", 65'
A
Perhaps bash should clarify this issue in its documents such that users like me
would not be misguided again.
Thanks
2011/6/23 Jonathan Nieder <jrnie...@gmail.com>:
> Hi,
>
> Yunfeng Wang wrote:
>
>> $ printf %c 65 66 67
>> 666
>>
>> The expected output is ABC, i.e. characters with ASCII code of 65 66 67
>
> I believe the current behavior is correct. POSIX (XCU.4.printf) sayeth[*]:
>
> 11. The argument to the 'c' conversion specifier can be a string
> containing zero or more bytes. If it contains one or more
> bytes, the first byte shall be written and any additional bytes
> shall be ignored. If the argument is an empty string, it is
> unspecified whether nothing is written or a null byte is written.
>
> I would suggest using something like
>
> perl -e 'print(chr(65), chr(66), chr(67), "\n");'
>
> or
>
> for i in 65 66 67
> do
> eval printf \'\\$(printf %03o "$i")\'
> done
> printf '\n'
>
> for your application.
>
> Back to the bug: I don't see any explanation of "printf %c" when I run
> "man bash". Perhaps your manual is different from mine, but if you,
> perhaps it would be possible to suggest a few words to explain this
> for future readers.
>
> Thanks and regards,
> Jonathan
>
> [*] http://unix.org/2008edition/
>
