If you save the following in a file named tester:

Code:

#!/bin/ksh
width=${1:-5}
printf '%s\n' 123 12345 12345678 "" S12 | awk -v w="$width" ' 
{	if((len = length($1)) >= w)
		printf("%s\n", $1)
	else	printf("%0*d%s\n", w - len, 0, $1)
}'

make it executable and invoke it with:

Code:

./tester

it, produces the output:

Code:

00123
12345
12345678
00000
00S12

If you invoke it with:
./tester 10
it produces the output:

Code:

0000000123
0000012345
0012345678
0000000000
0000000S12

and, if you invoke it with:

Code:

./tester 2

it produces the output:

Code:

123
12345
12345678
00
S12

Although this script was written and tested using a Korn shell, it will work with any shell that performs the basic parameter expansions required in the POSIX shell.

Does this help?

PS: As always, if you want to try this on a Solaris/SunOS system, change awk to /usr/xpg4/bin/awk or nawk.