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title: Debugging workflows - shell access
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Copyright (C) The Arvados Authors. All rights reserved.

SPDX-License-Identifier: CC-BY-SA-3.0
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To use this feature, your Arvados installation must be configured to allow container shell access. See "the install guide":{{site.baseurl}}/install/container-shell-access.html for more information.

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The @arvados-client@ program can be used to connect to a container in a running workflow. It can be installed from packages (@apt install arvados-client@ or @dnf install arvados-client@). The @arvados-client shell@ command provides an ssh connection into a running container.

h2(#syntax). Syntax

The @arvados-client shell@ tool has the following syntax:

<notextile>
<pre><code>~$ <span class="userinput">arvados-client shell -h</span>
arvados-client shell: open an interactive shell on a running container.

Usage: arvados-client shell [options] [username@]container-uuid [ssh-options] [remote-command [args...]]

Options:
  -detach-keys string
      set detach key sequence, as in docker-attach(1) (default "ctrl-],ctrl-]")

</code></pre>
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The @arvados-client shell@ command calls the ssh binary on your system to make the connection. Everything after _[username@]container-uuid_ is passed through to your OpenSSH client.

h2(#Examples). Examples

Connect to a running container, using the container request UUID:

<notextile>
<pre><code>~$ <span class="userinput">arvados-client shell ce8i5-xvhdp-e6wnujfslyyqn4b</span>
root@0f13dcd755fa:~#
</code></pre>
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The container UUID also works:

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<pre><code>~$ <span class="userinput">arvados-client shell ce8i5-dz642-h1cl0sa62d4i430</span>
root@0f13dcd755fa:~#
</code></pre>
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SSH port forwarding is supported:

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<pre><code>~$ <span class="userinput">arvados-client shell ce8i5-dz642-h1cl0sa62d4i430 -L8888:localhost:80</span>
root@0f13dcd755fa:~# nc -l -p 80
</code></pre>
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And then, connecting to port 8888 locally:

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<pre><code>~$ <span class="userinput">echo hello | nc localhost 8888</span>
</code></pre>
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Which appears on the other end:

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<pre><code>~$ <span class="userinput">arvados-client shell ce8i5-dz642-h1cl0sa62d4i430 -L8888:localhost:80</span>
root@0f13dcd755fa:~# nc -l -p 80
hello
</code></pre>
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