The power to our lab machines is controlled by a device we built in 2001. It uses the serial port to control a bank of relays. For more information on the device and how to build it, see this article. Now, it turns out that we often need to simply turn on all machines and then turn them all off when we are done. While we had used a TCL/TK Wish interface with buttons for individual machines, it is useful to have a command that turns off every box, or turns them all on. To further complicate things, there needs to be a delay between turning on each relay because of voltage transients. It also gave us a chance to brush up on Bash. Here is a simple script to turn on all of the relays:
[usr-1@srv-1 ~]$ cat allon #!/bin/bash for ((i=100;i<=115;i+=1)); do echo $i sleep 1 echo $i > /dev/ttyS1 done [usr-1@srv-1 ~]$ |
Let’s run the script after making it executable:
[usr-1@srv-1 ~]$ chmod 700 allon [usr-1@srv-1 ~]$ ./allon 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 [usr-1@srv-1 ~]$ |
Here is a script to turn them all off again:
[usr-1@srv-1 ~]$ cat alloff #!/bin/bash for ((i=200;i<=215;i+=1)); do echo $i sleep 1 echo $i > /dev/ttyS1 done [usr-1@srv-1 ~]$ |
Let’s make the script executable and run it:
[usr-1@srv-1 ~]$ chmod 700 alloff [usr-1@srv-1 ~]$ ./alloff 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 [usr-1@srv-1 ~]$ |
