On Tue, 18 Jun 2013, Matthew Cengia wrote:
On 2013-06-18 19:04, Tim Connors wrote: [...]
This seems to be a suitably hacking way of doing it:
# build an array of all replacements /0../32 to /0.0.0.0 -> # /255.255.255.255 so that any occurences can quickly be replaced # globally in any required filter cidr2netmaskfilter= for cidr in `seq 0 32` ; do netmask=`cidr2mask "$cidr"` cidr2netmaskfilter="$cidr2netmaskfilter; s!/$cidr !/$netmask!g" done
function filter_cidr2mask () { sed "$cidr2netmaskfilter" } [...]
Hi Tim,
A couple of pointers: I'd discourage the use of seq[1]. If you're using bash, which I assume you are given that's available on all RHEL instances, I'd use {0..32} instead of `seq 0 32`.
Never heard of that before. Definitely not POSIX (gut feeling here - no POSIX reference manual handy, but it doesn't work in dash). Never seen seq not work (assumed it was posix - I even saw it work on HP-UX of all things. Heck, it probably even works on SCO).
I also advice using $(cidr2mask "$cidr") rather than `cidr2mask "$cidr"`; The $() notation is newer and more predictable, especially with regard to quoting.
Yeah, trying to get out of the habit (` is still prettier for small snippets), however I thought $(prog) is not POSIX (I'm straying well away from posix in this program anyway), whereas ` is. (how do you google for "`" and "$(" ?)
Also, what *is* cidr2mask? I've not seen it anywhere before.
You own favourite shell function. Not the one I originally wrote which seemed to work for the common cases until I threw a non-class address at it while testing months after initial deploy (woops!) (meh, famous last words, it's not like it's ever going to be used elsewhere other than our class B). Here's some useful network calculations someone might find useful (after suitably debugging and commenting), that should never be deployed in production because I do silly things like work out what $0 is (so can be symlinked to netcalc, bcasecacl, cidr2mask, mask2cidr) without any sanity checking: http://rather.puzzling.org/~tconnors/code/cidr2mask
Further, your sed appears to be expecting a space after "$cidr", but isn't putting one back after "$netmask". That could give you grief.
Woops, that what happens when you want to fly out of the door before 7 and it's already 7:04. Tested fine! Good thing I ran with --noop rather than deploying across the cluster :) It's only me on call. Guess I better check my phone to see whether anyone called while I was on the bike :)
Finally, were I writing this myself (in the absense of cidr2mask), I'd probably do something like the following:
| filter_cidr2mask(){ | cidr=( | 0.0.0.0 | 128.0.0.0 | 192.0.0.0 | 224.0.0.0 | 240.0.0.0 | 248.0.0.0 | 252.0.0.0 | 254.0.0.0 | 255.0.0.0 | 255.128.0.0 | 255.192.0.0 | 255.224.0.0 | 255.240.0.0 | 255.248.0.0 | 255.252.0.0 | 255.254.0.0 | 255.255.0.0 | 255.255.128.0 | 255.255.192.0 | 255.255.224.0 | 255.255.240.0 | 255.255.248.0 | 255.255.252.0 | 255.255.254.0 | 255.255.255.0 | 255.255.255.128 | 255.255.255.192 | 255.255.255.224 | 255.255.255.240 | 255.255.255.248 | 255.255.255.252 | 255.255.255.254 | 255.255.255.255 | )
Urk. Big array not generated by a simple loop.
| sedExp= | for ((i=0; i<=32; i++)); do | sedExp+="s!/\<$i\>!/${cidr[$i]}!g; " | done | | sed "$sedExp" | }
1. <greybot> seq(1) is a highly nonstandard program used to count to 10 in silly Linux howtos. Use one of these: for ((i = 1; i <= 10; i++)); do ... (bash 2.04+/zsh/ksh93), i=; while ((i++ <= 10)); do ... (bash/mksh/ksh88), i=; while [ $(( ( i += 1 ) <= 10 )) -ne 0 ]; do ... (POSIX). Don't do this: for x in $(...); do ... Don't do this: for i in {1..10}; do ...
Heh. -- Tim Connors