if the file changes send email about diff
I have 2 script. Script "A", Script "B".

Script A is regulary watching the `dhcpacks` [dhcp release is configured to 2mins] in the logs, for the past 2 minutes. It writes the MAC addresses to a file [`/dev/shm/dhcpacks-in-last-2min.txt`] every 2 minutes. Ok, this is working, active clients are in this file. Super!

Script B: [On pastebin][1]

I'm trying to create a script, that watches the changes in `/dev/shm/dhcpacks-in-last-2min.txt` file ( every 1 sec). Ok. But: my watcher script [the pastebined][1] is not working fine - sometime it works, sometime it sends that someone `XY logged out`, but it's not true! Nothing happened, and the problem is not in the Script A.

Can someone help me point out, what am I missing? How can I watch a file (in every sec), that contains only MAC addresses, and if someone doesn't get `dhcpack` in 2 minutes, the file `/dev/shm/dhcpacks-in-last-2min.txt` changes, and that clients MAC address will be gone from it, and i need to know, who was it [pastebined my script - but somethings wrong with it].

Thank you for any help..I've been pathing my script for days now.. :\


  [1]: http://pastebin.com/rfvt0Dhq
if the file changes send email about diff
===

I have 2 script. Script "A", Script "B".

Script A is regulary watching the `dhcpacks` [dhcp release is configured to 2mins] in the logs, for the past 2 minutes. It writes the MAC addresses to a file [`/dev/shm/dhcpacks-in-last-2min.txt`] every 2 minutes. Ok, this is working, active clients are in this file. Super!

Script B: [On pastebin][1]

I'm trying to create a script, that watches the changes in `/dev/shm/dhcpacks-in-last-2min.txt` file ( every 1 sec). Ok. But: my watcher script [the pastebined][1] is not working fine - sometime it works, sometime it sends that someone `XY logged out`, but it's not true! Nothing happened, and the problem is not in the Script A.

Can someone help me point out, what am I missing? How can I watch a file (in every sec), that contains only MAC addresses, and if someone doesn't get `dhcpack` in 2 minutes, the file `/dev/shm/dhcpacks-in-last-2min.txt` changes, and that clients MAC address will be gone from it, and i need to know, who was it [pastebined my script - but somethings wrong with it].

Thank you for any help..I've been pathing my script for days now.. :\


  [1]: http://pastebin.com/rfvt0Dhq