I start a new shell (new terminal window), then here are all the commands I run:
user@host :~ $ eval "$(ssh-agent -s)"
Agent pid 1413341
user@host :~ $ ssh-add -vvv ~/.ssh/keys/<mykey>
Enter passphrase for /home/mate/.ssh/keys/<mykey>:
user@host :~ $ ssh-add -l
The agent has no identities.ssh-add doesn't return any output, but after verification, returns an error code of 1 (tried ssh-add ... again then echo $?). However, it really doesn't print any output on stderr.
The env vars $SSH_AGENT_PID and $SSH_AUTH_SOCK are correctly set after the eval "$(ssh-agent -s)" command.
PS: Also tried the full operation with eval "$(ssh-agent)" instead, to no avail.
PS: Unless I missed something, all questions on stackoverflow, superuser, and unix.stackexchange are dealing with another specific case, such as running ssh-add alone (and thus only taking standard key locations into account) or people who haven't started the agent correctly etc...
1 Answer
Alright, turns out it was apparently due to a needed (very recent) package update, cause it works again now after a system update and a reboot.
Out of all packages updated matched against dependencies of openssh, the culprit seems to be tzdata. So check pending package updates on your system.
PS: Take this with a grain of salt cause there are many entangled dependencies of which I'm not sure how all of this works under the hood (libcap libcap-ng, libgcrypt libxcrypt, etc...).
