bash scripts fail while trying to use list

Question

I found a bash script to validate ip addresses here: http://www.linuxjournal.com/content/validating-ip-address-bash-script

When i try to run it I get the error :

 test.sh: line 22: syntax error: unexpected "(" (expecting "fi")

Line 22 looks like this:

  ip=($ip)

Question

1. Is this line supposed to be creating a list or array?

2. I've tried two different shells, and neither work. tried:

   #!/bin/bash

and also

 #!/bin/sh

Any suggestions would be appreciated.

Answer 1

That:

test.sh: line 22: syntax error: unexpected "(" (expecting "fi")

is not an error message that bash reports. It is one that the Almquist shell and its derivatives like dash or busybox sh report though:

$ grep -z '(expecting' /bin/dash
%s unexpected (expecting %s)

ash-based shells don't support arrays, that script is meant for bash (3.2 or above) as the #!/bin/bash she-bang indicates, though it looks more like a mix between bash, zsh and ksh93 syntax if it's meant to check for quad-decimal IPv4 addresses where the parts are limited to 3 decimal digits (in bash, it would give some errors about 008.008.008.008 for instance).

With standard POSIX sh syntax which both dash and bash recognise, you could do instead:

valid_ip() (
  IFS=.
  set -o noglob
  set -- $1''
  [ "$#" -eq 4 ] || exit
  for i do
    case $i in
      ("" | *[!0-9]*) exit 1;;
    esac
    [ "$i" -le 255 ] || exit
  done
)

Answer 2

This works:

#!/bin/bash

ip=127.0.0.1

ip=($ip)

printf 'The first IP number is "%s"\n' "${ip[0]}"

If you're running this under bash, then you have something else wrong in your script relating to an if statement. If you're running this under /bin/sh, then it should fail as sh doesn't know about arrays.

I'd suggest you run your script through ShellCheck at https://www.shellcheck.net/

Answer 3

1) Is this line supposed to be creating a list or array?

It's creating an array. First it sets the IFS to . and then it says ip=($ip). So if your ip=10.11.12.13 your array would be ip=([0]=10 [1]=11 [2]=12 [3]=13) Then it goes on to verify that each octet is less than 256.

2) What shell should this use

This script is definitely made for bash and therefore should be ran in bash.

3) What is my issue

The issue is that you have modified the script in some way that has caused a syntax error. Please post the full script exactly as you are running it and we can try to figure it out. Additionally as I said in my comment, you must name this script valid_ip.sh. Failure to do such shouldn't cause your error but it will also make the script not work.