# Using the AWS PCS multi-cluster login node configuration script
<a name="multi-cluster-login-script-usage"></a>

## Running the script
<a name="running-script"></a>

**To run the configuration script**

1. Save the [content of the script](multi-cluster-login-script-code.md#multi-cluster-login-script-code-content) in a file named:

   ```
   pcs-multi-cluster-login-configure.sh
   ```

1. Make it executable:

   ```
   chmod +x pcs-multi-cluster-login-configure.sh
   ```

1. Run the script:

   ```
   ./pcs-multi-cluster-login-configure.sh --cluster-identifier {{cluster-name}}
   ```

## Cluster interaction environments
<a name="activation-script-usage"></a>

After successful configuration, the script generates a cluster-specific activation script in the current directory. The script has the name `activate-pcs-{{cluster-name}}`. The activation script configures the necessary environment variables and paths to interact with the target cluster.

**To activate a cluster environment**
+ Use the `source` command to run the activation script

  ```
  source ./activate-pcs-{{cluster-name}}
  ```  
**Example**  

  ```
  # Activate cluster environment for cluster 'my-cluster'
  source ./activate-pcs-my-cluster
  
  # Now you can use Slurm commands
  sinfo
  squeue
  sbatch my-job.sh
  ```

**What the activation script does**
+ Sets the `SLURM_CONF` environment variable to point to the cluster's configuration.
+ Updates the `PATH` to include the cluster's Slurm binaries.
+ Configures other necessary Slurm environment variables (`MANPATH`, `LD_LIBRARY_PATH`).
+ Sets AWS PCS cluster identification variables.
+ Enables seamless interaction with the target AWS PCS cluster.

**To deactivate a cluster environment**
+ Run the deactivation command.

  ```
  deactivate-pcs-{{cluster-name}}
  ```  
**Example**  

  ```
  # After activating a cluster
  source ./activate-pcs-my-cluster
  
  # Work with the cluster
  sinfo
  
  # Deactivate when done
  deactivate-pcs-my-cluster
  ```

**What the deactivate command does**
+ Restores the original `PATH` environment variable.
+ Unsets cluster-specific Slurm environment variables.
+ Returns the shell environment to its pre-activation state.

**Note**  
The activation is session-specific and must be sourced in the shell session where you want to interact with the cluster.