CODEWITHSUNDEEP
bashstring
Felipe Alvarez
Felipe Alvarez

Reputation: 3908

I need to pad IP addresses with Zeroes for each octet

Starting with a string of an unspecified length, I need to make it exactly 43 characters long (front-padded with zeroes). It is going to contain IP addresses and port numbers. Something like:

### BEFORE
# Unfortunately includes ':' colon
66.35.205.123.80-137.30.123.78.52172:
### AFTER
# Colon removed.
# Digits padded to three (3) and five (5) 
# characters (for IP address and port numbers, respectively)
066.035.005.123.00080-137.030.123.078.52172

This is similar to the output produced by tcpflow.

Programming in Bash. I can provide copy of script if required.
If it's at all possible, it would be nice to use a bash built-in, for speed. Is printf suitable for this type of thing?

Upvotes: 1

Views: 1960

Answers (2)

Dennis Williamson
Dennis Williamson

Reputation: 360325

This uses IFS to split the address info into an array. Then printf saves the formatted result back into the original variable for further processing. Pure Bash - no external executables are used.

addr='66.35.205.123.80-137.30.123.78.52172:'
saveIFS=$IFS
IFS='.-:'
arr=($addr)
IFS=$saveIFS
printf -v addr "%03d.%03d.%03d.%03d.%05d-%03d.%03d.%03d.%03d.%05d" ${arr[@]}
do_something "$addr"

Edit:

Without using an array:

addr='66.35.205.123.80-137.30.123.78.52172:'
saveIFS=$IFS
IFS='.-:'
printf -v addr "%03d.%03d.%03d.%03d.%05d-%03d.%03d.%03d.%03d.%05d" $addr
IFS=$saveIFS
do_something "$addr"

Upvotes: 3

unwind
unwind

Reputation: 399949

Yes, sounds like an excellent match for printf. You can probably use cut to split the incoming address into fields, which you can then feed back into printf to do the formatting.

Here's a quick sketch, it can certainly be improved to get the exact output format that you require:

#!/usr/bin/env bash

function format_address()
{
    printf "%03d.%03d.%03d.%03d.%05d" $(echo $1 | cut -d'.' --output-delimiter=' ' -f1-5)
}

for a in $(echo $1 | tr -d ':' | cut -d '-' --output-delimiter=' ' -f1,2)
do
    format_address $a
done

Upvotes: 1

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