As reported in issue #11 on the github repository of check_equallogic, there was a problem when a volume didn't exist. Instead of showing a message indicating that the given volume does not exists, the plugin returned with an error:

awk: line 1: syntax error at or near end of line
/usr/lib/nagios/plugins/check_snmp_dell_equallogic.sh: line 848: / 1024: syntax error: operand expected (error token is "/ 1024")
UNKNOWN: should never reach this part```

The bugfix release 20151006 of check_equallogic fixes this bug. Thanks to Stephane Loeuillet for the report and the fix suggestion. Please download the newest version from here: http://www.claudiokuenzler.com/nagios-plugins/check_equallogic.php. 

Important note: To actually hit the now fixed bug, a human error was mandatory. Because it only affects the "vol" check which requires the name of a volume as an argument. If the given volume does not exist, then the bug was hit.