Convention/standard on using curly braces around options

You can use sfdisk for this task even in GPT partitioned disks*.

Save:

sfdisk -d /dev/sdX > part_table

Restore keeping the same disk & partition IDs**:

sfdisk /dev/sdX < part_table

Restore generating new disk & partition IDs**:

grep -v ^label-id part_table | sed -e 's/, *uuid=[0-9A-F-]*//' | sfdisk /dev/sdY

Notes

*: For GPT partition tables, this requires sfdisk from util-linux 2.26 or later. It was re-written from scratch on top of libfdisk.

**: by default sfdisk will copy the disk and partition IDs unchanged, rather than generating new ones. So the new disk will be a clone of the original, not just another disk with the same layout. Note that Linux's /dev/disk/by-uuid/ looks at filesystem UUIDs, though, not UUIDs in the partition table. sfdisk will generate new UUIDs if you delete the references to partitions ids (, uuid=...) and the reference to the disk id (label-id: ...) from the dump .

Here's a quick and dirty solution to this in Python. It does caching (including negative caching), but no threading and isn't the fastest thing you've seen. If you save it as something like rdns, you can call it like this:

zcat /var/log/some-file.gz | rdns
# ... or ...
rdns /var/log/some-file /var/log/some-other-file # ...

Running it will annotate the IP addresses with their PTR records in-place:

$ echo "74.125.132.147, 64.34.119.12." | rdns
74.125.132.147 (rdns: wb-in-f147.1e100.net), 64.34.119.12 (rdns: stackoverflow.com).

And here's the source:

#!/usr/bin/env python

import sys, re, socket

cache = dict()

def resolve(x):
    key = x.group(0)
    try:
        return "%s (rdns: %s)" % (key, cache[key])
    except KeyError:
        try:
            cache[key] = socket.gethostbyaddr(key)[0]
        except socket.herror:
            cache[key] = '?'
        return "%s (rdns: %s)" % (key, cache[key])

for f in [open(x) for x in sys.argv[1:]] or [sys.stdin]:
    for line in f:
        sys.stdout.write(re.sub("\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}", resolve, line))

# End of file.

Please note: this isn't quite what you're after to the letter (using ‘standard tools’). But it probably helps you more than a hack that resolves every IP address every time it's encountered. With a few more lines, you can even make it cache its results persistently, which would help with repeat invocations.