feh, hostname, fc, ssh-add: move to common (#6487)

pages/common/ssh-add.md

@@ -0,0 +1,28 @@
+# ssh-add
+
+> Manage loaded ssh keys in the ssh-agent.
+> Ensure that ssh-agent is up and running for the keys to be loaded in it.
+
+- Add the default ssh keys in `~/.ssh` to the ssh-agent:
+
+`ssh-add`
+
+- Add a specific key to the ssh-agent:
+
+`ssh-add {{path/to/private_key}}`
+
+- List fingerprints of currently loaded keys:
+
+`ssh-add -l`
+
+- Delete a key from the ssh-agent:
+
+`ssh-add -d {{path/to/private_key}}`
+
+- Delete all currently loaded keys from the ssh-agent:
+
+`ssh-add -D`
+
+- Add a key to the ssh-agent and the keychain:
+
+`ssh-add -K {{path/to/private_key}}`