cidr-merger

A simple utility to merge ip/ip cidr/ip range, support IPv4/IPv6

$ cidr-merger --help
Usage: cidr-merger [OPTION]... [FILE]...
Write sorted result to standard output.
Options:
     --batch               batch mode (default if input files supplied or stdin
                           is not a tty), read file content into memory, then
                           write to the specified file
     --cidr                print as ip/cidr (default if not console mode)
 -c, --console             console mode(default if no input files supplied and
                           stdin is a tty), all input output files are ignored,
                           write to stdout immediately
     --empty-policy=value  indicate how to process empty input file
                             ignore(default): process as if it is not empty
                             skip: don't create output file
                             error: raise an error and exit
 -e, --error-if-empty      same as --empty-policy=error
 -h, --help                show this help menu
     --ignore-empty        same as --empty-policy=ignore
 -k, --skip-empty          same as --empty-policy=skip
     --merge               sort and merge input values (default)
     --original-order      output as the order of input, without merging
 -o, --output=file         output values to <file>, if multiple output files
                           specified, the count should be same as input files,
                           and will be processed respectively
 -r, --range               print as ip ranges
     --simple              output as single ip as possible (default)
                             ie. 192.168.1.2/32 -> 192.168.1.2
                                 192.168.1.2-192.168.1.2 -> 192.168.1.2
 -s, --standard            don't output as single ip
 -v, --version             show version info

Sample Usage:
```shell script
$ echo ‘1.0.0.1-223.255.255.254’ | cidr-merger

1.0.0.1
1.0.0.2/31
1.0.0.4/30
1.0.0.8/29
……
1.128.0.0/9
2.0.0.0/7
4.0.0.0/6
8.0.0.0/5
16.0.0.0/4
32.0.0.0/3
64.0.0.0/2
128.0.0.0/2
192.0.0.0/4
208.0.0.0/5
216.0.0.0/6
220.0.0.0/7
222.0.0.0/8
223.0.0.0/9
……
223.255.255.240/29
223.255.255.248/30
223.255.255.252/31
223.255.255.254
$ echo ‘1.1.1.0’ > a; \
echo ‘1.1.1.1’ > b; \
echo ‘1.1.1.2/31’ > c; \
echo ‘1.1.1.3-1.1.1.7’ > d; \
cidr-merger -o merge a b c d; \
cat merge; \
rm a b c d merge
1.1.1.0/29
$ wget -O- “https://ftp.apnic.net/stats/apnic/`TZ=UTC date +%Y/delegated-apnic-TZ=UTC+24 date +%Y%m%d`.gz” | \
gzip -d | awk -F| ‘!/^\s(#.)?$/&&/CN|ipv4/{print $4 “/“ 32-log($5)/log(2)}’ | \
cidr-merger -eo/etc/chinadns_chnroute.txt # update ip on router
$ # ^ e: means error if input is empty
$ echo ‘fe80::/10’ | cidr-merger -r
fe80:ffffffffffffffff
$ echo ‘1.1.1.0’ > a; echo ‘1.1.1.1’ | cidr-merger - a; rm a
$ # ^ -: means standard input
1.1.1.0/31
```

Difference between standard and simple(default)
```shell script
$ echo ‘1.1.1.1/32’ | cidr-merger

1.1.1.1
$ echo ‘1.1.1.1/32’ | cidr-merger -s
1.1.1.1/32
$ echo ‘1.1.1.1/32’ | cidr-merger -r
1.1.1.1
$ echo ‘1.1.1.1/32’ | cidr-merger -rs
1.1.1.1-1.1.1.1
```

Difference about empty policy
``shell script $ cidr-merger -o txt /dev/null # an empty file namedtxtis created. $ cidr-merger -ko txt /dev/null # no file is created, and this program exit with code zero $ # ^ same ascat /dev/null | cidr-merger —skip-empty —output txt$ cidr-merger -eo txt /dev/null # no file is created, and this program exit with code non zero $ # ^ same ascat /dev/null | cidr-merger —error-if-empty —output txt$ # option-e` might be useful when download file from internet and then write to a file

$ # There is no difference if you redirect output to a file such as following
$ cat /dev/null | cidr-merger -e > txt

file txt is created, but this program exit with code non zero

```