Ubuntu typing 'php' in terminal shows a lot of errors

Simply remove php5-snmp package. You can use this command in a console to do so:

sudo apt-get remove php5-snmp

With PHP 7, the package is php7.0-snmp:

sudo apt-get remove php7.0-snmp

For those of us that need the php5-snmp package, the above may not solve your problem. In that case you can try:

sudo apt-get install snmp

which will install snmp for you, which seems to be required for the php5-snmp package to avoid outputting those errors.

apt-get install snmp-mibs-downloader

Isn't this the best answer? Found @ https://serverfault.com/questions/440285/why-does-snmp-fail-to-use-its-own-mibs

If you're using php 5. Simply remove php5-snmp package

sudo apt-get remove php5-snmp

If you're using php 7. Remove php7.0-snmp package.

sudo apt-get remove php7.0-snmp