I need to set up a strange system through which an arbitrary command is sent to a number of different servers (well, actually, VPS accounts). We have a command "vpass" that "passes" a command from the root level to resident VPS accounts. Suppose I wanted each VPS to do some trivial thing, like report its hostname. I might use a script like:

Code:

for account in `cat accountlist`
do
vpass $account hostname
done

So, as you can see, the vpass syntax is:

Code:

vpass accountname command__to_run

Now, it would be convenient to set up a little script that runs an arbitrary command that's in a file called "command". To replicate the results above, I create "command" with "hostname" in it, and then do:

Code:

cmd=$(cat command)

for account in `cat accountlist`
do
        vpass $account $cmd
done

That works just right. However, more complex commands fail. For example, this works:

Code:

for account in `cat accountlist`
do
vpass $account mysql --user=root --password=p@ssword -e "USE database ; SELECT stuff FROM table ORDER BY RAND() LIMIT 1;"
done

However, putting that exact MySQL command into the "command" file fails. If I add a line "echo $cmd" after the variable assignment, it gives exactly the right command back, yet passing it into the vpass command fails.

Any suggestions on where the failure might come from? I'm at a loss, mainly because of time-induced brain fuzziness. Many thanks in advance.


Update:

I added -x and checked the results... Apparently some strange things are being done to the command:

Code:

vpass acct1 mysql --user=root --password=p@ssword -e '"USE' database ';' SELECT stuff FROM table ORDER BY 'RAND()' LIMIT '1;"'

It seems to my naive troubleshooting that those changes-- the addition of single-quotes throughout the command-- must be the cause of the problem, unless I misunderstand the output of -x.

Update 2:

I don't know why this didn't occur to me before... lack of sleep? Anyway, xargs helps...

Code:

cat command | xargs vpass $account

So, that works, but I'm a little perturbed that the other method doesn't. If only for my own education, I'd appreciate any thoughts on why that's failing.