Nagios XI - NRPE: Unable to read output

Error:

NRPE: Unable to read output

How to reproduce:

$ /usr/local/nagios/libexec/check_nrpe -H 172.22.232.11 -c df.sh
NRPE: Unable to read output

Checks:

1. Ensure that the command you are using, df.sh in this case, is declared in /usr/local/nagios/etc/nrpe.cfg file.

command[df.sh]=sudo /usr/local/nagios/libexec/df.sh

2. Ensure that the user nagios can run command, as per configurations done in /etc/sudoers file. If not, please add below line.

nagios    ALL=(ALL)   NOPASSWD:/usr/local/nagios/libexec/df.sh

3. Also make sure that requiretty option is disabled in /etc/sudoers file. If it is enabled, it prevents any user from running sudo commands from non-TTY sessions. In other words, a non-root user must be using a TTY to execute a sudo command. This option is enabled, by default, in CentOS, and can be disabled by commenting it out as shown below.

#Defaults    requiretty

Result:

$ /usr/local/nagios/libexec/check_nrpe -H 172.22.232.11 -c df.sh
OK- (/)= 6%;(/dev/shm)= 0%;(/boot)= 34%;(/var1)= 43%;(/home)= 41%;(/usr1)= 27%;(/data1)= 17%; | (/)= 6%;(/dev/shm)= 0%;(/boot)= 34%;(/var1)= 43%;(/home)= 41%;(/usr1)= 27%;(/data1)= 17%;

Hope this helps.