Shell Programming and Scripting

My apologies if any confusion caused!
I should be more specific with my examples. My input format always starts with char/string and followed by numbers of different length. So my original example starts with single char, which is

Code:

S1
S2 
S12 
S21

expected output is:

Code:

S01
S02
S12
S21

and second example starts with string:

Code:

sk1
sk12
sk321
sk1344

output is:

Code:

sk0001
sk0012
sk0321
sk1344

The printf utility (or awk printf function) is not able to determine where digits are in an alphanumeric string. This clarified my question, anyway.
Yoda's answer seems to be the first choice for me, so that I can strip the leading char(s) then handle the rest digits with printf format identifier.
Thanks a lot again!

Here is an awk approach that might work:-

Code:

awk '
        NR == FNR {
                m = ( m < length ? length : m )
                next
        }
        {
                match( $0, /[0-9]/ )
                format = "%s%0" ( m - RSTART ) + 1 "d\n"
                printf format, substr($0, 1, RSTART-1 ), substr( $0, RSTART )
        }
' file file

Since you refused to answer most of my questions, I will make one final attempt at trying to handle a general case. Since you didn't give enough information about the desired output format, I'll make some code that reads input strings and produces output strings with the following characteristics:Since you refused to specify the length of the desired ending zero filled decimal digit output string, I'll use awk for this example to avoid reading the input file twice:

Code:

awk '
BEGIN {	m = 1
}
{	tail[NR] = substr($0, match($0, /[[:digit:]]*$/))
	head[NR] = substr($0, 1, RSTART - 1)
	if(RLENGTH > m)
		m = RLENGTH
}
END {	for(i = 1; i <= NR; i++)
		printf("%s%0*d\n", head[i], m, tail[i])
}' file

If file contains:

Code:

S1
S2
S12
S21
sk1
sk12
sk321
sk1344
strange1prefix2long99
123

it produces the output:

Code:

S0001
S0002
S0012
S0021
sk0001
sk0012
sk0321
sk1344
strange1prefix2long0099
0123

and if file just contains the 1st four input lines shown above, the output would be:

Code:

S01
S02
S12
S21

Thanks Don!
I never meant to refuse to answer your question. Wish I did not offend you when I should have pointed my reply corresponding to your very question.
Originally I was trying to find the format specifier of printf() to pad any alphanumeric string in each row. Googled for a while, no luck. Yoda's first reply DID give the answer of my example, but not in the way I could think of. However, your first reply clarified that there is no such specifier for printf() to pad alphanumeric string.
Then I gave a second example to describe what I was looking for, which is padding numbers of the alphanumeric string with "0". The padding is only for the numeric part of the string.
Your "final attempt" did give more than what I wanted, as my case is not that complicated.
Did I answer your questions now?!
Thanks a lot!

Hi yifangt,

As you may have figured out, already, the string containing the representation of numbers must be subdivided and reinterpreted as part unmodified string and part zero padded number.

test.file

Code:

S1
S2
S12
S21
sk1
sk12
sk321
sk1344
strange1prefix2long99
123

Code:

$ perl -ne 'printf "%s%04s\n", /(\w*?)(\d+)$/' test.file

Code:

S0001
S0002
S0012
S0021
sk0001
sk0012
sk0321
sk1344
strange1prefix2long0099
0123

Just as my inital post here:
Change digits to 4, and change s to sk...

Code:

...
digits=4
printf "SK%0${digits}d\n" $numbers

Cheers n' good bye

I wasn't offended; just disappointed...

In post #1 in this thread, you said:
and the four sample inputs you provided and the output you said you wanted seemed to indicate that you wanted two digit, leading zero filled numbers. And Yoda showed you how to do that.

In post #3, you said:
which I misread to mean that you wanted to use some character to pad numeric strings other than the <space> and <digit 0> fill that printf format strings %4d and %04d provide. And, I showed you how you can use any character you want instead of space and zero.

So, in post #6 you said:
and you gave four more sample input strings and showed us the output you wanted for those specific four input strings. And, the samples implied that you wanted four digit zero filled numbers this time. Note that there is nothing in the above description that says that the string part of the input is alphabetic, fixed length, nor constant. Therefore, from the given descriptions to this point, there is no way to know where string ends and number begins for any input line, other than by making assumptions based on your two samples.

So, in post #7 in this thread, I said:
And, in post #8, you replied:
followed by the same two examples given earlier and repeating that the 1st example had a character that needed to be stripped and the 2nd example had a string (not two character string, not alphabetic string, not even fixed length string; just string) that needed to be stripped. You didn't supply any information that clearly defined the input string formats your script is supposed to handle, anything indicating if your script will receive a parameter indicating the width of the output string, anything indicating if your script will receive a parameter indicating how many digits should be displayed in the numbers, anything indicating if your script will receive a parameter indicating the desired fill character, and nothing indicating how to reliably determine the end of the initial "string" and the start of the "number" in your input.

So, I tried to come up with a set of requirements for a script that would read input in a format that seemed to cover all of your sample descriptions, write output based on characteristics of the input being processed, and produce output consistent with all of your sample descriptions. And then I wrote a script that tried to fulfill those requirements. It is relatively complicated because it has to deduce several parameters to be applied to the output by examining the input and making assumptions based on what it finds.

If the input alpha string is a constant number of characters for a given invocation of your script, my script can be simplified. If the input alpha string is the same string on every line for a given invocation of your script, my script can be simplified. If you tell the script how many digits you want in the number portion of the output, my script can be simplified. But, you still haven't told use: