> ## Documentation Index > Fetch the complete documentation index at: https://docs.tokenfactory.nebius.com/llms.txt > Use this file to discover all available pages before exploring further. # use - Choose an image for the session Set the session image or show the current session state. This is typically the first command you run – it tells contree-cli which image to use for subsequent commands. ## Examples ```bash theme={null} # Start a session with an image eval $(contree use tag:ubuntu:latest) # Start a session with a specific image UUID eval $(contree use 3f2a7b...) # Start or resume a named session export CONTREE_SESSION=my-session # Show current session info contree use # Start a fresh session (new session key) eval $(contree use -N tag:python:3.11-slim) ``` The `eval` wrapper exports `CONTREE_SESSION` into your shell so all subsequent commands share the same session. Without `eval`, contree prints the export line but your shell doesn’t pick it up. ## Help output

\$ contree use --help

usage: contree use \[-h] \[-N] \[image]

Set or show the current session image.

With an IMAGE argument, resolves it (UUID or tag:NAME) and sets it as
the active session image. Prints a shell export line so that the
session key can be captured with eval:

  eval \$(contree use tag:ubuntu:latest)

Without arguments, displays the current session info (image, branch,
last operation).

Use -N/--new to start a fresh session instead of resuming the current
one. The new session key is printed as an export line.

positional arguments:
  image       Image UUID or tag

options:
  -h, --help  show this help message and exit
  -N, --new   Start a new session instead of resuming the current one

for coding agents:
  use IMAGE starts/switches a session and prints CONTREE\_SESSION export
  use (without IMAGE) is read-only and prints current session state
  use --new IMAGE creates a fresh session key
  without CONTREE\_SESSION env var, key is auto-generated as \+\<8hex>
  (derived from profile+ppid+tty); export your own for stability

agent note:
  Before using this command in an automated workflow, read:
    contree agent

## Behavior **With an image argument**: resolves the image (UUID or `tag:NAME`), sets it as the session’s current image, and prints a shell export statement. **Without arguments**: displays the current session info – session key, active branch, current image, and last operation. **With `--new`**: generates a new random session key instead of resuming the existing one. Useful when you want a clean slate in the same terminal. ## Shell detection The output format adapts to your shell: * **bash / zsh**: `export CONTREE_SESSION=` * **fish**: `set -gx CONTREE_SESSION ` Detection uses the `$SHELL` environment variable. ## See also * [Your First Sandbox](../tutorial/first-steps) – starting your first session * [Sessions, Branches & Rollback](../tutorial/sessions) – branching and rollback