> ## Documentation Index
> Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Use variables to retrieve the results of running commands
> Learn to capture and reuse command output in Ansible playbooks using the register directive for improved automation and task management.
In this article, you'll learn how to capture the output of tasks executed with Ansible using the `register` directive and reuse that data later in your playbook. Capturing command output can be invaluable—for instance, if you want to read the contents of a file and then use that information in subsequent tasks.
## Capturing Command Output with a Registered Variable
Consider the following playbook that executes a shell command to display the contents of the `/etc/hosts` file on each host. Initially, the playbook might be written like this without capturing the output:
```yaml theme={null}
- name: Check /etc/hosts file
hosts: all
tasks:
- shell: cat /etc/hosts
- debug:
var:
```
When you run the playbook, the output might look similar to this:
```Ansible theme={null}
PLAY [Check /etc/hosts file] *********************************************************
TASK [shell] **************************************************************************
changed: [web1]
changed: [web2]
PLAY RECAP ***************************************************************************
web1 : ok=1 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
web2 : ok=1 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
```
To capture the output, you can register the result of the shell command into a variable (for example, `result`). The revised playbook is shown below:
```yaml theme={null}
- name: Check /etc/hosts file
hosts: all
tasks:
- shell: cat /etc/hosts
register: result
- debug:
var: result
```
When executed, Ansible stores the result of the shell command into the `result` variable. Running the updated playbook produces debug output that looks like this:
```Ansible theme={null}
PLAY [Check /etc/hosts file] ******************************************************************
TASK [shell] **********************************************************************************
changed: [web1]
changed: [web2]
PLAY RECAP ************************************************************************************
web1 : ok=1 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
web2 : ok=1 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
```
## Understanding the Registered Variable Content
The content stored in the `result` variable depends on the module that was executed. When using the shell module, the output is captured as a JSON object. For example, the `result` variable might contain data like the following:
```json theme={null}
{
"ok": {
"web2": {
"output": {
"ansible_facts": {
"discovered_interpreter_python": "/usr/bin/python"
}
},
"changed": true,
"cmd": "cat /etc/hosts",
"failed": false,
"rc": 0,
"start": "2019-09-12 05:25:34.158877",
"end": "2019-09-12 05:25:34.161974",
"delta": "00:00:00.003097",
"stderr": "",
"stderr_lines": [],
"stdout": "127.0.0.1\tlocalhost\n::1\tlocalhost ip6-localhost ip6-loopback\nfe00::0\tip6-localnet\nff00::0\tip6-mcastprefix\nff02::1\tip6-allnodes\nff02::2\tip6-allrouters\n172.20.1.101\tweb2",
"stdout_lines": [
"127.0.0.1\tlocalhost",
"::1\tlocalhost ip6-localhost ip6-loopback",
"fe00::0\tip6-localnet",
"ff00::0\tip6-mcastprefix",
"ff02::1\tip6-allnodes",
"ff02::2\tip6-allrouters",
"172.20.1.101\tweb2"
]
}
}
}
```
This JSON output includes several key attributes:
* **rc**: The return code of the command (0 indicates success).
* **stdout** and **stdout\_lines**: The standard output from the command, which in this example is the contents of `/etc/hosts`.
* **stderr** and **stderr\_lines**: Any error messages generated during command execution.
* **Timestamps and delta**: Timing details that show when the command started, ended, and the duration of execution.
Registered variables in Ansible are host-scoped. This means the variable is only available for the specific host where the task was executed and can be accessed throughout the remainder of the playbook for that host.
## Accessing Specific Elements from the Registered Variable
In many cases, you might only want to display specific parts of the command output. For instance, if you're only interested in the standard output (the file contents of `/etc/hosts`), you can reference `result.stdout` in your debug task:
```yaml theme={null}
- name: Check /etc/hosts file
hosts: all
tasks:
- shell: cat /etc/hosts
register: result
- debug:
var: result.stdout
```
Similarly, if you want to check the command's return code, you can reference `result.rc`:
```yaml theme={null}
- name: Check /etc/hosts file
hosts: all
tasks:
- shell: cat /etc/hosts
register: result
- debug:
var: result.rc
```
## Using Registered Variables Across Multiple Plays
Since registered variables are host-scoped, you can also access them in subsequent plays within the same playbook. For example:
```yaml theme={null}
- name: Check /etc/hosts file
hosts: all
tasks:
- shell: cat /etc/hosts
register: result
- debug:
var: result.rc
- name: Second Play
hosts: all
tasks:
- debug:
var: result.rc
```
This approach makes it possible to carry information from one set of tasks to another throughout your playbook.
## Verifying Command Output with Verbose Mode
Another convenient way to view task output is to run your playbook with the `-v` option. This provides verbose output without the need to add explicit debug statements. For more details, refer to the [Ansible Documentation](https://docs.ansible.com/ansible/latest/index.html).
That’s it for now. Practice these techniques to further enhance your Ansible playbooks and streamline your automation processes.