Comments on: Zero Padding in Bash

By: Jonathan

Jonathan — Wed, 17 Feb 2010 16:41:04 +0000

@cdaaawg: It works if you type it yourself. The blog software replaced the second quotation mark of the padding variable in Benoit’s post with a fancy one.

By: cdaaawg

cdaaawg — Wed, 17 Feb 2010 16:27:14 +0000

@Benoit Terradillos
Running your code under bash 3.2.39(1), I get the following output:
00000″0
00000″1
00000″2
00000″3
00000″4
00000″5
00000″6
00000″7
00000″8
00000″9
0000″10

Bizarre!

– Carl

By: Benoît Terradillos

Benoît Terradillos — Fri, 29 Jan 2010 17:37:36 +0000

Even more simple (based on Hernan solution):

padding=”00000″ # put as much zeros as you want.
for ((i=0; i<31; i+=1))
do
echo ${padding:${#i}}$i
done

By: A grateful visitor

A grateful visitor — Mon, 05 Oct 2009 07:16:39 +0000

ZOMG, you have no idea how much this helped a ‘nix n00b like me.

2 years on and this webpage is still helping people.

Thanks a lot!

By: Krayon (Todd Harbour)

Krayon (Todd Harbour) — Fri, 04 Sep 2009 17:31:40 +0000

It would appear this blog software messed with my comment :(

The 3rd and 4th lines were merged into one. They should be:

[ $1 -gt $expo ] AMPAMP { echo $1; return; }
formatd=$(($1 + $expo))

where AMPAMP is 2 ampersands.

By: Krayon (Todd Harbour)

Krayon (Todd Harbour) — Fri, 04 Sep 2009 17:27:05 +0000

I use this rather “simple” solution, somewhat similar to Heman’s, though it requires >= bash 2.02:

function zeropad {
expo=$((10 ** $2))
[ $1 -gt $expo ] &formatd=$(($1 + $expo))
echo ${formatd:1}
}

Example:
zeropad 59 10
0000000059

By: Hernan

Hernan — Tue, 16 Jun 2009 22:42:46 +0000

Calling printf will create a new process every time; this may be a little slow for some applications. A better performing example:

#!/bin/bash

(( million = 1000000 ))
(( index = 1 ))

while [ $index -lt 500000 ]
do
(( printme = index + million ))
(( index = index + 1 ))
echo ${printme:1}
done

(See the “Shell Parameter Expansion” section of the bash manual for an explanation of what ${printme:1} does.)

On my machine at least (running Debian 4.0; bash v3.1.17) this is 12x faster than the printf version.

The “printf” solution is way more legible, of course.

By: jimmy

jimmy — Fri, 24 Apr 2009 22:06:25 +0000

neat tip — thanks!!

By: Mike H

Mike H — Sun, 15 Mar 2009 00:38:47 +0000

thanks a plenty for the printf, jot and sed info guys.. now I have my script sorted and saving me a huge amount of time when it comes to the image files I am processing.

cheers

By: Logan

Logan — Wed, 14 Jan 2009 06:05:45 +0000

for ((i=1;i<=11;i+=1)); do
s=`printf “%02d” $i`;
echo $s;
done

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