---
layout: page
title: "Shell interpreter for Apache Zeppelin"
description: "Shell interpreter uses Apache Commons Exec to execute external processes."
group: interpreter
---
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{% include JB/setup %}

# Shell interpreter for Apache Zeppelin

<div id="toc"></div>

## Overview
Zeppelin Shell has two interpreters the default is the %sh interpreter.

### Shell interpreter
Shell interpreter uses [Apache Commons Exec](https://commons.apache.org/proper/commons-exec) to execute external processes. 
In Zeppelin notebook, you can use ` %sh ` in the beginning of a paragraph to invoke system shell and run commands.

### Terminal interpreter
Terminal interpreter uses [hterm](https://chromium.googlesource.com/apps/libapps/+/HEAD/hterm), [Pty4J](https://github.com/JetBrains/pty4j) analog terminal operation.

> **Note :** Currently each command runs as the user Zeppelin server is running as.

## Configuration
At the "Interpreters" menu in Zeppelin dropdown menu, you can set the property value for Shell interpreter.

<table class="table-configuration">
  <tr>
    <th>Name</th>
    <th>Default</th>
    <th>Description</th>
  </tr>
  <tr>
    <td>shell.command.timeout.millisecs</td>
    <td>60000</td>
    <td>Shell command time out in millisecs</td>
  </tr>
  <tr>
    <td>shell.working.directory.user.home</td>
    <td>false</td>
    <td>If this set to true, the shell's working directory will be set to user home</td>
  </tr>
  <tr>
    <td>zeppelin.shell.auth.type</td>
    <td></td>
    <td>Types of authentications' methods supported are SIMPLE, and KERBEROS</td>
  </tr>
  <tr>
    <td>zeppelin.shell.principal</td>
    <td></td>
    <td>The principal name to load from the keytab</td>
  </tr>
  <tr>
    <td>zeppelin.shell.keytab.location</td>
    <td></td>
    <td>The path to the keytab file</td>
  </tr>
  <tr>
    <td>zeppelin.shell.interpolation</td>
    <td>false</td>
    <td>Enable ZeppelinContext variable interpolation into paragraph text</td>
  </tr>
</table>

## Example

### Shell interpreter
The following example demonstrates the basic usage of Shell in a Zeppelin notebook.

<img src="{{BASE_PATH}}/assets/themes/zeppelin/img/docs-img/shell-example.png" />

If you need further information about **Zeppelin Interpreter Setting** for using Shell interpreter, 
please read [What is interpreter setting?](../usage/interpreter/overview.html#what-is-interpreter-setting) section first.

### Kerberos refresh interval
For changing the default behavior of when to renew Kerberos ticket following changes can be made in `conf/zeppelin-env.sh`.

```bash
# Change Kerberos refresh interval (default value is 1d). Allowed postfix are ms, s, m, min, h, and d.
export LAUNCH_KERBEROS_REFRESH_INTERVAL=4h
# Change kinit number retries (default value is 5), which means if the kinit command fails for 5 retries consecutively it will close the interpreter. 
export KINIT_FAIL_THRESHOLD=10
```

### Object Interpolation
The shell interpreter also supports interpolation of `ZeppelinContext` objects into the paragraph text.
The following example shows one use of this facility:

####In Scala cell:

```scala
z.put("dataFileName", "members-list-003.parquet")
    // ...
val members = spark.read.parquet(z.get("dataFileName"))
    // ...
```

####In later Shell cell:

```bash
%sh
rm -rf {dataFileName}
```

Object interpolation is disabled by default, and can be enabled (for the Shell interpreter) by
setting the value of the property `zeppelin.shell.interpolation` to `true` (see _Configuration_ above).
More details of this feature can be found in [Zeppelin-Context](../usage/other_features/zeppelin_context.html)

### Terminal interpreter
The following example demonstrates the basic usage of terminal in a Zeppelin notebook.

```bash
%sh.terminal
input any char
```

<img src="{{BASE_PATH}}/assets/themes/zeppelin/img/docs-img/shell-terminal.gif" />