summarize a list of IP addresses, verifying IP address and giving counts for each IP found

function summaryIP() { < $1 awk '{print $1}' | while read ip ; do verifyIP ${ip} && echo ${ip}; done | awk '{ip_array[$1]++} END { for (ip in ip_array) printf("%5d\t%s\n", ip_array[ip], ip)}' | sort -rn; }
Working with lists of IP addresses it is sometimes useful to summarize a count of how many times an IP address appears in the file. This example, summarizeIP, uses another function "verifyIP" previously defined in to ensure only valid IP addresses get counted. The summary list is presented in count order starting with highest count.
Sample Output
Example file containing a list of IPs:
$ nl list_of_IPs
     8  some junk which should not be here
    13  1001.4.5.6

Having defined functions summaryIP and verifyIP (from previous posting):

$ summaryIP list_of_IPs

By: mpb
2015-05-01 16:45:05

What Others Think

OK, I can see a few things I can tidy :-) . 'read' is greedy, so everything gets put in ip. We can be smarter using a second variable: ... | while read ip X; do ip contains the first field as delimited by $IFS and X contains the rest of the line. That means we don't need the first awk any more. . We can drop the braces around ${ip} (I think you've spent too long in some other scripting language) However, it's best to quote the filename "$1". As for the second awk, I'd go "old-school" and replace it with sort, uniq, sort. . That leaves: function summaryIP() { while read ip x; do verifyIP $ip && echo $ip; done < "$1" | sort | uniq -c | sort -rn; } 111 characters, down from 206 :-) . For extra points, replace "$1" with "${1:-/dev/stdin}" to allow both: summaryIP FILENAME cat FILENAME | summaryIP . function summaryIP() { while read ip x; do verifyIP $ip && echo $ip; done < "${1:-/dev/stdin}" | sort | uniq -c | sort -rn; }
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CooperRaff · 53 weeks and 4 days ago
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Killersmile · 30 weeks and 1 day ago

What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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