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Wow, didn't really expect you to read this far down. The latest iteration of the site is in open beta. It's a gentle open beta-- not in prime-time just yet. It's being hosted over at UpGuard (link) and you are more than welcome to give it a shot. Couple things:
This command line detect ldap hosts, by mandatory dns entry, then ping them to detect response average. based on ping response average it sorts and print the faster server in first output line
This allows for sleeping in between pings. Also, espeak needs to be installed.
Audio acknowledgement for host availability.
When running the command from a Linux systems, you can use "festival" or "espeak" instead of "say".
Everytime You Run Bash It Will Run And Send The Command To Background In A Loop Forever. This Is Useful In Android To Avoid Getting Discconnected While Using ADB Or Other Services Like SSH By Being Inactive For Long Periods Of Time. In My Case I Get Bash Full Suport Only Through ADB And Also A Decent Python Interpreter Using Python For Android.
Waits for all pings to complete and returns ip with mac address
Pings all the hosts on 192.168.1.0/24 in parallel, so it is very fast. Alive host IP addresses are echoed to stdout as pings are responded to.
Cleaned up and silent with &>/dev/null at the end.
Execute commands serially on a list of hosts. Each ssh connection is made in the background so that if, after five seconds, it hasn't closed, it will be killed and the script will go on to the next system.
Maybe there's an easier way to set a timeout in the ssh options...
%t are tens. %d are digits. One may have further outer loops to provide hundreds, thousands, etc.
This example applies ping to the numbered machines. The pattern can be used in other ways to apply all combinations of components to a task.
For less time
Nasty perl one-liner that provides a sparkline of ping times. If you want a different history than the last 30, just put that value in. It (ab)uses unicode to draw the bars, inspired by https://github.com/joemiller/spark-ping . It's not the most bug-free piece of code, but what it lacks in robustness it makes up for in capability. :)
If anyone has any ideas on how to make it more compact or better, I'd love to hear them.
I included a ping to google in the command just as an example (and burned up 10 chars doing it!). You should use it with: $ ping example.com | $SPARKLINE_PING_COMMAND
A simple way to find all machines on a network subnet is pinging a broadcast address (-b flag). First run ifconfig ifconfig. Then use "Bcast" address and '-b' flag in ping
Linux - starting with a packetsize that must be split into two packets, count down by 8 bytes, and try to send the packet using the "Don't Fragment" option. The actual MTU (the size of the actual PING packet) is (in this example) 1460 data bytes + 20 bytes IP header + 8 bytes PING request = 1488
This command uses ping to get the routers' IP addresses to the destination host as traceroute does. If you know what I mean..
I have used single packet, and in a silent mode with no display of ping stats. This is with color and UI improvement to the http://www.commandlinefu.com/commands/view/10220/check-if-a-machine-is-online. It is as per the enhancements suggested.
c 1 limits to 1 pinging attempt
q makes the command quiet (or silent mode)
/dev/null 2>&1 is to remove the display
&& echo ONLINE is executed if previous command is successful (return value 0)
|| echo OFFLINE is executed otherwise (return value of 1 if unreachable or 2 if you're offline yourself).
I personally use this command as an alias with a predefined machine name but there are at least 2 improvements that may be done.
Asking for the machine name or IP
Escaping the output so that it displays ONLINE in green and OFFLINE in red (for instance).
Every 20 minutes test if host with IP 192.168.0.14 is 'dead' or not reachable.
The line should be put in your crontab file.