With a lot of help from my friends I wrote a bash script that displays the number of kilobytes being uploaded & downloaded every second via my eth0 internet connection. The ouput looks like: $ monitor 10.8 k/s 2.3 k/s 22.3 k/s 1.3 k/s 12.1 k/s 3.1 k/s ... The logic of the script goes something like this: init: invoke netstat to retrieve initial packet counts do forever: invoke netstat to retrieve next packet counts compute kilobyte delta = packet delta * MTU / 1024 display results This works fine and displays plausible results, but they seem to differ somewhat (+20-30%) from an earlier version that collected byte counts from the kernel's /proc/net/dev pseudo-file. I understand that the above approach is not entirely correct since I wait one second (how accurate is that on a multi-processing OS?) but also, some correction factor would need to be applied to account for the elapsed time that is necessary for the code itself to execute .. the fact this is a bash script at this point probably doesn't help. I also realize that there are probably CLI tools that already do something similar. I definitely would be curious if any one recommended something that might display this information and I would take a look as to how their authors went about doing this. Naturally, I don't need anything highly accurate .. this is both an exercise to try and understand these aspects better .. and something that will display two counters at the bottom of my screen so I have some idea of what is going on with the system. Thanks!

On 15 Dec 2007 19:23:46 GMT, cga2000 <cga2000@optonline.net> wrote: > With a lot of help from my friends I wrote a bash script that displays > the number of kilobytes being uploaded & downloaded every second via my > eth0 internet connection. > > The ouput looks like: > > $ monitor > > 10.8 k/s 2.3 k/s > 22.3 k/s 1.3 k/s > 12.1 k/s 3.1 k/s > ... > > The logic of the script goes something like this: > > init: > > invoke netstat to retrieve initial packet counts > > do forever: > > sleep 1 > invoke netstat to retrieve next packet counts > compute kilobyte delta = packet delta * MTU / 1024 > display results > > This works fine and displays plausible results, but they seem to differ > somewhat (+20-30%) from an earlier version that collected byte counts > from the kernel's /proc/net/dev pseudo-file. > > I understand that the above approach is not entirely correct since I > wait one second (how accurate is that on a multi-processing OS?) but > also, some correction factor would need to be applied to account for > the elapsed time that is necessary for the code itself to execute .. > the fact this is a bash script at this point probably doesn't help. > > I also realize that there are probably CLI tools that already do > something similar. I definitely would be curious if any one recommended > something that might display this information and I would take a look > as to how their authors went about doing this. > > Naturally, I don't need anything highly accurate .. this is both an > exercise to try and understand these aspects better .. and something > that will display two counters at the bottom of my screen so I have some > idea of what is going on with the system. > > Thanks! > fat fingers .. lost the " sleep 1" above .. sorry