CODEWITHSUNDEEP
bashshellnetwork-programmingscripting
Martijn
Martijn

Reputation: 521

getting network id from ip address & subnetmask

I am trying to learn some shell scripting and I though it would be a nice way to combine it with my ccna study. So I am writing a simple script that scans some network devices based upon a ip address and a subnetmask provided by the user. To determine the network a host belongs to I use the following lines of code, but it keeps getting me errors.

read -p "Geef een IP-adres op "  i
read -p "Geef een subnetmask op "  s

IFS=. read -r i1 i2 i3 i4 <<< $i
IFS=. read -r m1 m2 m3 m4 <<< $s

ip=`printf "%d.%d.%d.%d\n" $i1 $i2 $i3 $i4`
mask=`printf "%d.%d.%d.%d\n" $m1 $m2 $m3 $m4`

#bepaal netwerk id
id=`printf "%d.%d.%d.%d\n" "$((i1 & m1))" "$((i2 & m2))" "$((i3 & m3))" "$((i4 & m4))"`

The error is produce is as follows:

192 168 178 15 &  0xff 0xff 0xff 0x00: syntax error in expression (error token is "168 178 15 &  0xff 0xff 0xff 0x00")

Anyone here that can tell me why?

Upvotes: 4

Views: 600

Answers (1)

viraptor
viraptor

Reputation: 34145

The problem is with quoting the variables fed to the read call. If you do this instead (add the quotes):

IFS=. read -r i1 i2 i3 i4 <<< "$i"
IFS=. read -r m1 m2 m3 m4 <<< "$s"

Everything works again. Still not sure why.

Upvotes: 4

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