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1

I have a script that generates some output. I want to check that output for any IP address like 

159.143.23.12
134.12.178.131
124.143.12.132

if (IPs are found in <file>)
then // bunch of actions //
else // bunch of actions //

Is fgrep a good idea?

I have bash available.

share|improve this question
    
use grep , egrep , awk , or sed , whatever u like – Ijaz Khan yesterday
    
Could you help with the syntax please? I mean how does it search for a random IP. How to describe the pattern? I would be looking for any IP address, not a particular address. – Koshur yesterday
4  
Is that only IPv4 addresses in quad-decimal notation? Could they be written like 0010.0000.0000.0001? May the file otherwise contain things that look like IP addresses like version numbers (soft-1.2.1100.1.tar.gz, network specifications (10.0.0.0/24), 1.2.3.4.5)? Would you accept a solution that is positive on 333.444.555.666? Or 0377.0377.0377.0377 (a valid quad-octal IP address)? – Stéphane Chazelas yesterday
up vote 3 down vote

Yes , You have lot of options/tools to use. I just tried this , it works:

ifconfig | grep -oE "\b([0-9]{1,3}\.){3}[0-9]{1,3}\b"

so you can use grep -oE "\b([0-9]{1,3}\.){3}[0-9]{1,3}\b" to grep the ip addresses from your output.

share|improve this answer
    
Thanks. This works. Can you explain a bit? Is this a regular expression? – Koshur yesterday
    
Yes this is a regular expression used in bash with grep , you are just looking for three digits pattern separated by dots. you can play with by changing the numbers in {1,2} for 2 consecutive digits and so on – Ijaz Khan yesterday
up vote 1 down vote

Redirect that output to some outputFile

Simply grep it with pattern as,

grep -sE "159.143.23.12|134.12.178.131|124.143.12.132" <outputFile>
share|improve this answer
4  
Note that . is a regular expression operator and needs escaping for it to be treated literally – Stéphane Chazelas yesterday
up vote 1 down vote

If your file is called e.g ips you can write somethinng like:

while read -r ip
    do
        if [[ $ip == "$1" ]]; then
            shift
            printf '%s\n' 'action to take if match found'
        else
            printf '%s\n' 'action to take if match not found'
        fi
    done < ips

Then you can pass the parameters as follow the the script

./myscript 159.143.23.12 134.12.178.131 124.143.12.132 124.143.12.132

share|improve this answer
up vote 0 down vote

starting my answer based on this answer:

Yes , You have lot of options/tools to use. I just tried this , it works:

ifconfig | grep -oE "\b([0-9]{1,3}.){3}[0-9]{1,3}\b" a so you can use grep -oE "\b([0-9]{1,3}.){3}[0-9]{1,3}\b" to grep the ip addresses from your output.

and converting the answer to full length IPv6, etc...:

fgrep -oE "\b([0-9A-Fa-f]{1,4}:){7}[0-9A-Fa-f]{1,4}\b" -- file

if you want to keep the /nnn if it's there:

fgrep -oE "\b([0-9A-Fa-f]{1,4}:){7}[0-9A-Fa-f]{1,4}(/[0-9]{1,3}){0,1}\b" -- file

and also there's the shortened version of IPv6 that includes '::'.

for more IPv6 answers you can look here: http://stackoverflow.com/questions/53497/regular-expression-that-matches-valid-ipv6-addresses

share|improve this answer
    
fgrep is the old name for a variant of grep that ignores pattern matching. I'd recommend you use grep (or even egrep) instead, especially as you're clearly wanting pattern matching. – roaima yesterday

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