I'm the newbie on Linux and blockhain. I'm have installed Linux on the small piece of my hard drive (50 GB), so I want to know how to change the directory for blockchain data on my external hard drive. I use Linux Mint 18.2.
It depends on how Parity is started. If you're starting from the command line, you can use these flags:
-d --base-path PATH Specify the base data storage path. --db-path PATH Specify the database directory path (default: $BASE/chains). --keys-path PATH Specify the path for JSON key files to be found (default: $BASE/keys).
If Parity is not started from the command line, you should first figure out how to make it not start automatically (that depends on your operating system -- on Mac your remove the LaunchAgent).
There also a user_defualts file that you can search for information about. That lets you set certain startup params. I'm not sure if the path variables are in that file or not.
Before you do anything though, please make sure to backup your private keys. Do not say I didn't warn you.