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I have set up automatic (password less) ssh login to some servers using ssh-copy-id. ssh-agent works only from the terminal where it was run. How do I get ssh-add to work in all my terminals?

Naturally, I would not prefer SSH key without a passphrase.

3 Answers 3

46

If you're logging into a graphical session, arrange to start ssh-agent during your session startup. Some distributions already do that for you. If yours doesn't, arrange to run ssh-agent from your session startup script or from your window manager. How you do that depends on your desktop environment and your window manager. For example, if you start your window manager manually, simply replace the call to my_favorite_wm by ssh-agent my_favorite_wm.

Do not start ssh-agent from .bashrc or .zshrc, since these files are executed by each new interactive shell. The place to start ssh-agent is in a session startup file such as .profile or .xsession.

If you want to use the same SSH agent on all processes no matter where you logged in from, you can make it always use the same socket name, instead of using a randomly-named socket. For example, you might put this in your ~/.profile:

export SSH_AUTH_SOCK=~/.ssh/ssh-agent.$HOSTNAME.sock
ssh-add -l 2>/dev/null >/dev/null
if [ $? -ge 2 ]; then
  ssh-agent -a "$SSH_AUTH_SOCK" >/dev/null
fi
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  • 3
    FYI, the reason it checks for $? -ge 2 is because exit code 1 is when the ssh-agent has no keys, but ssh-agent is already running.
    – wisbucky
    Aug 9, 2019 at 23:00
  • Note that some desktop environments (e.g. Ubuntu Mate) may automatically run ssh-agent for you but you have to run ssh-add without parameters to add private keys into your keyring. For example, when you first connect to remote machine that contains private keys, you have to run ssh-add on the remote matchine to get the keys into your client machine keyring. Mar 21, 2020 at 9:51
  • 1
    I am curious, when it's possible to set this up in a few lines of a shell script, what is the purpose of keychain, ssh-ident or other projects. Apr 12, 2020 at 10:29
  • FYI, if you have a .bashrc file, you have to put theses lines instead of .profile (see head ~/.profile for explanations)
    – Asenar
    Nov 10, 2020 at 10:01
  • @Asenar No. .profile is the right file for what runs at login time. .bashrc runs every time you open a terminal. See superuser.com/questions/183870/… Nov 10, 2020 at 10:50
11

You probably want a program such as Keychain, which was designed for this exact purpose. From the man page:

DESCRIPTION
   keychain is a manager for ssh-agent, typically run from ~/.bash_profile.
   It allows your shells and cron jobs to share a single ssh-agent process.
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  • really like this one!
    – Colin D
    May 11, 2017 at 14:45
  • Great! thank you. Works perfectly.
    – Somebody
    May 7, 2019 at 16:22
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    What is the advantage of keychain over the the accepted answer? Apr 12, 2020 at 10:31
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    @PavelŠimerda Interestingly, I found this question when trying to figure out how to accomplish this without keychain, as I've been using it for (literally) decades now. I'm answering another Super User question and wanted to provide the basic ssh-agent instructions. That said, I think keychain is great for (at least) several reasons, at least for my workflow preferences. (1) It's a single command that consolidates ssh-agent and ssh-add into a one-liner and "just works". (2) One-liners keep my profile "cleaner". (3) It outputs fish shell syntax (my preferred shell). Jan 18 at 22:28
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    @NotTheDr01ds, keychain also supports gpg, which is also great Jun 20 at 19:08
4

Apply it to your desktop environment or window manager. When I've done this manually in the past with a custom ~/.Xclients, I just used this as the last line:

ssh-agent mywindowmanger

There might be some DE's that have their own setup options for this, although it appears to me that (e.g.) KDE does not. Currently, it seems that mine was run via code from /etc/X11/xinit/xinitrc-common (presumably something done by fedora), since it is active for all users regardless of DE/WM and the parent process command is $HOME/.Xclients, but that file does not reference ssh-agent (whereas /etc/X11/xinit/xinitrc-common does).

If you don't have a ~/.Xclients, you could create one with just that one line, but you will need to know the command that starts your DE/WM.

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