I would like to check number of MySQL databases. I've created simple test "plugin":

Location: `/var/lib64/nagios/plugins



db=$(mysql -e 'SHOW DATABASES' | wc -l)
echo $db

It works from the local machine:

# ./test 
  • however when executed from Nagios server it displays "0"

NRPE config:


Nagios server:

# ./check_nrpe -H -c "test"


  • 1
    Log the output of the db=$(mysql -e 'SHOW DATABASES' | wc -l) to a file. Possibly mysql is not in $PATH and/or the user as which it runs has no access to MySQL. – faker Jun 27 '12 at 12:28
  • 1
    Has the nagios user access to run the mysql command without any passwords etc? Try with su! – HampusLi Jun 27 '12 at 13:08

NPRE commands usually run as nagios. It seems like your query is actually polling how many databases your nagios user can see.

There are several solutions to your problem:

  • Add user and password information to your command (mysql -uroot -proot -e 'SHOW DATABASES' | wc -l);
  • Add nagios to your sudoers file, so that he can run mysql as root (nagios ALL=(ALL) NOPASSWD:/usr/bin/mysql -e 'SHOW DATABASES');
  • Add a nagios user to your database with sufficient permissions to see all databases (mysql documentation) - RECOMMENDED;

BTW, you should consult http://nagios.sourceforge.net/docs/3_0/pluginapi.html as the output from the shown in your plug-in script is quite non-standard for Nagios andf will cause problems.

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