Add a private key to your ssh agent from a variable.

I always have a hard time remembering how to add an ssh key (ssh-add) from an environment variable containing the private key. “In a variable!?” You may exclaim, don’t worry it’s typically a ‘secret’ variable on a continous integration system that supports masking sensitive variable key/values. I wouldn’t recommend doing this unless you’re certain the value of your variable is not going to accidently leak in plain text .

To redirect the contents of the environment variable into ssh-add instead of a real file simply use:

eval $(ssh-agent -s) 
ssh-add <(echo "$PRIVATE_KEY") 

# List out your new key's fingerprint
ssh-add -l

# Don't forget to cleanup your agent after you're done using it if you're not on an ephemeral build server.
ssh-agent -k

The more general lesson here is <(echo "$VAR") is good for redirecting variables instead of a file incases where a good old pipe | just won’t work.