Problems With mon_disk_space Script? (VMware KB 2058187)

I recently attempted to deploy the mon_disk_space script from VMware KB 2058187. The instructions from the KB are straightforward; users only need to modify the below two values to get started:

# Please provide email for alert messages
# Please provide percentage threshold for PostgreSQL used disk space

The script should send an email to the address provided when the PostgreSQL volume is utilizing more capacity than the provided (as a percentage) threshold. For my testing, I put the initial value at 10 knowing it would trigger the email to send.

After copying the script to /etc/cron.hourly on the VCSA and running ‘chmod 700 /etc/cron.hourly/mon_disk_space‘ to ensure the script is executable by cron, emails still were still not showing up, even after waiting over an hour. The troubleshooting began…

First, make sure cron is attempting to execute the script by running:

grep cron /var/log/vmware/messages

You should find entries similar to this in the log:

run-parts[51761]: (/etc/cron.hourly) starting mon_disk_space
run-parts[51761][51796]: (/etc/cron.hourly) finished mon_disk_space

If you see those entries, then cron is able to execute the script, so the problem seems to be within the script itself. If you take a look at line 9 of the provided script, the variable ‘db_type’ is populated by running:

cat /etc/odbc.ini | grep DB_TYPE | awk -F= '{print $2}' | tr -d ' '

When I run that single command against my 6.7 VCSA, I get these duplicate values:

vcsa [ ~ ] cat /etc/odbc.ini | grep DB_TYPE | awk -F= '{print $2}' | tr -d ' '

Let’s take a look at the provided script again. Lines 10-12 are looking for a single “PostgreSQL” entry, but the VCSA is providing back two values. This condition causes the script to exit, which explains why no emails are sent.

Simply adding a ‘uniq’ to line 9 will cause the script to produce a single, unique value. Line 9 of mon_disk_space ends up looking like this:

db_type=`cat /etc/odbc.ini | grep DB_TYPE | awk -F= '{print $2}' | uniq | tr -d ' '`

After making the change, I manually triggered the cron job by running run-parts /etc/cron.hourly. The alert properly triggered, and the email showed up in my inbox. Lastly, don’t forget to go back and modify the alerting threshold on line 6 of the script to something more sensible.

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Perl Script to Modify Hostname and IP

I have taken on Perl scripting as a directed study. One of the projects going on at work is to take our 32 RaspberryPi’s and turn them into a “super computer” of sorts. We have the master and node images captured, but I have been working on a script that we can run to modify the hostnames and IP addresses of all the nodes post-imaging.

Below is my script which accepts user input for the Hostname and IP.

# This needs to be run with sudo
print "Please enter the new hostname: n";
$newName = ;

#Attempt to edit the hostname file
$hostFile = "/etc/hostname";

open (FILE1, ">$hostFile") or die "Can't open $hostFile: $! n"; 
print FILE1 "$newNamen";
close FILE1;

print "Hostname file has been modified! n";

#Edit the hosts file and replaces the hostname

$hostsFile = "/etc/hosts";

open(FILE, "<$hostsFile") || die "Can't open $hostsFile: $! n";
my @lines = ;

my @newlines;
foreach(@lines) {
   $_ =~ s/NodePi01/$newName/g;                       
print "Hosts orginal contents have been modified with new Hostname... n";
open(FILE2, ">$hostsFile") || die "Can't open $! n";
print FILE2 @newlines;
print "Hosts file has been successfully modified! n";

#Does the IP configuration....
print "Please enter the new IP Address: n";
$newIP = ;
$dhcp = "dchp";
$static = "static";
$ipFile = "/etc/network/interfaces";

open(IP, "<$ipFile") || die "Can't open $ipFile: $! n";
my @lines2 = ;

my @newlines2;
foreach(@lines2) {
   $_ =~ s/iface eth0 inet dhcp/iface eth0 inet $staticn address $newIPn netmask gateway;                       
print "Interface file orginal contents have been modified with new settings... n";
open(FILE2, ">$ipFile") || die "Can't open $ipFile $! n";
print FILE2 @newlines2;
print "IP Address and network settings have been successfully modified! n";

#Code to reboot the node 
$reboot = '/sbin/init 6';
print "You must reboot to apply changes, do you want to reboot now? (yes/no)n";
chomp($input = );

if($input eq "yes") {
print "Now rebooting ....n";
system $reboot;
print "Bye !n";
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