I have a bitcoin-core-18.0 with on my linux mint, and I don't have downloaded the bitcoin with the ppa but I downloaded the official zip directory on site bitcoin.
Now my question is, c-lightning with this configuration bitcoin-core?
I'm running this command and I have this error
./bitcoin-0.18.0/bin/bitcoind -datadir=/media/vincenzo/Maxtor/BitcoinCore/node/ -daemon -testnet & ./clightning-v0.7.2.1/bin/lightningd --lightning-dir=/media/vincenzo/Maxtor/C-lightning/node/ --network=testnet --log-level=debug
2019-08-22T13:00:06.878Z DEBUG lightning_gossipd(9943): pid 9943, msgfd 20 bitcoin-cli not found. Is bitcoin-cli (part of Bitcoin Core) available in your PATH? Make sure you have bitcoind running and that bitcoin-cli is able to connect to bitcoind. You can verify that your Bitcoin Core installation is ready for use by running: $ bitcoin-cli -testnet echo 'hello world'
Exist some propriety configuration c-lightning?