Become Friends with find

A while back I noticed a tip posted somewhere on how to use the find utility to register a bunch a virtual machines at once. It was a really helpful post and illustrated some of the potential of the the Swiss Army-like find utility. But it overlooked one of the coolest features of find, the -exec option.

Using -exec, you can launch a command with find and pass each found file as a parameter to it, eliminating the need to run vmware-cmd in a for loop. Just place the command to run after the -exec parameter, and find will replace the string {} with the current file being processed:

[root@esx02 root]# find /vmfs/volumes/ -name '*.vmx' -exec vmware-cmd -s register {} \; register(/vmfs/volumes/495e44a0-d41258bc-fac4-000c299206d0/lab-dc1/lab-dc1.vmx) = 1 register(/vmfs/volumes/495e44a0-d41258bc-fac4-000c299206d0/lab-ex1/lab-ex1.vmx) = 1 register(/vmfs/volumes/495e44a0-d41258bc-fac4-000c299206d0/uda14-esx/uda14-esx.vmx) = 1

The -exec option is often considered less efficient than using xargs, which will feed multiple parameters to a command at once rather than launching the command with a single argument like -exec does. But for use with a command like vmware-cmd, which only expects to have one .vmx file passed to it, -exec is perfect.

And find has another option, -ok, which does the same thing but will present a prompt before running the command on each .vmx file that is found. This can be really handy if you are registering or powering on a bunch of VMs but know that there are some you are going to want to skip:

[root@esx02 root]# find /vmfs/volumes/ -name '*.vmx' -ok vmware-cmd -s register {} \; < vmware-cmd ... /vmfs/volumes/495e44a0-d41258bc-fac4-000c299206d0/lab-dc1/lab-dc1.vmx > ? y register(/vmfs/volumes/495e44a0-d41258bc-fac4-000c299206d0/lab-dc1/lab-dc1.vmx) = 1 < vmware-cmd ... /vmfs/volumes/495e44a0-d41258bc-fac4-000c299206d0/lab-ex1/lab-ex1.vmx > ? y register(/vmfs/volumes/495e44a0-d41258bc-fac4-000c299206d0/lab-ex1/lab-ex1.vmx) = 1 < vmware-cmd ... /vmfs/volumes/495e44a0-d41258bc-fac4-000c299206d0/uda14-esx/uda14-esx.vmx > ? n

find rules
I've been in a couple of jams where find really saved the day. Consider a situation where a standalone ESX server needs to be rebuilt, but the virtual machines are all on networked storage. Using find afterwards to register and start the VMs makes the process trivial:

[root@esx02 root]# find /vmfs/volumes/ -name 'lab*.vmx' -exec vmware-cmd -s register {} \; register(/vmfs/volumes/495e44a0-d41258bc-fac4-000c299206d0/lab-dc1/lab-dc1.vmx) = 1 register(/vmfs/volumes/495e44a0-d41258bc-fac4-000c299206d0/lab-ex1/lab-ex1.vmx) = 1 [root@esx02 root]# find /vmfs/volumes/ -name 'lab*.vmx' -exec vmware-cmd {} start \; VMControl error -16: Virtual machine requires user input to continue VMControl error -16: Virtual machine requires user input to continue [root@esx02 root]# find /vmfs/volumes/ -name 'lab*.vmx' -print -exec vmware-cmd {} getstate \; /vmfs/volumes/495e44a0-d41258bc-fac4-000c299206d0/lab-dc1/lab-dc1.vmx getstate() = stuck /vmfs/volumes/495e44a0-d41258bc-fac4-000c299206d0/lab-ex1/lab-ex1.vmx getstate() = stuck [root@esx02 root]# find /vmfs/volumes/ -name 'lab*.vmx' -print -exec vmware-cmd {} answer \; /vmfs/volumes/495e44a0-d41258bc-fac4-000c299206d0/lab-dc1/lab-dc1.vmx Question (id = 1) :msg.uuid.moved:The location of this virtual machine's configuration file has changed since it was last powered on. If the virtual machine has been copied, you should create a new unique identifier (UUID). If it has been moved, you should keep its old identifier. If you are not sure, create a new identifier. What do you want to do? 0) Create 1) Keep 2) Always Create 3) Always Keep 4) Cancel Select choice. Press enter for default ɘ> : 1 selected 1 : Keep /vmfs/volumes/495e44a0-d41258bc-fac4-000c299206d0/lab-ex1/lab-ex1.vmx Question (id = 1) :msg.uuid.moved:The location of this virtual machine's configuration file has changed since it was last powered on. If the virtual machine has been copied, you should create a new unique identifier (UUID). If it has been moved, you should keep its old identifier. If you are not sure, create a new identifier. What do you want to do? 0) Create 1) Keep 2) Always Create 3) Always Keep 4) Cancel Select choice. Press enter for default ɘ> : 1 selected 1 : Keep

You could even use the -ok option to introduce a pause between the VM start-ups.

Shrimp tacos
The syntax for -exec and -ok can be a little difficult to remember. The ; at the end of the command designates the end of the command find should execute, and it has to be escaped like \; so the shell doesn't interpret it.

I could never get the syntax right from memory until I associated it with shrimp tacos. The curly braces {} are a corn tortilla, and I'm using a spatula to get my shrimp off the skillet, \;

It may be corny, but I never forget the syntax now!