kubernetes/docs/user-guide/getting-into-containers.md

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<h2>PLEASE NOTE: This document applies to the HEAD of the source tree</h2>

If you are using a released version of Kubernetes, you should
refer to the docs that go with that version.

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<strong>
The latest release of this document can be found
[here](http://releases.k8s.io/release-1.1/docs/user-guide/getting-into-containers.md).

Documentation for other releases can be found at
[releases.k8s.io](http://releases.k8s.io).
</strong>
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# Getting into containers: kubectl exec

Developers can use `kubectl exec` to run commands in a container. This guide demonstrates two use cases.

## Using kubectl exec to check the environment variables of a container

Kubernetes exposes [services](services.md#environment-variables) through environment variables. It is convenient to check these environment variables using `kubectl exec`.


We first create a pod and a service,

```console
$ kubectl create -f examples/guestbook/redis-master-controller.yaml
$ kubectl create -f examples/guestbook/redis-master-service.yaml
```

wait until the pod is Running and Ready,

```console
$ kubectl get pod
NAME                 READY     REASON       RESTARTS   AGE
redis-master-ft9ex   1/1       Running      0          12s
```

then we can check the environment variables of the pod,

```console
$ kubectl exec redis-master-ft9ex env
...
REDIS_MASTER_SERVICE_PORT=6379
REDIS_MASTER_SERVICE_HOST=10.0.0.219
...
```

We can use these environment variables in applications to find the service.


## Using kubectl exec to check the mounted volumes

It is convenient to use `kubectl exec` to check if the volumes are mounted as expected.
We first create a Pod with a volume mounted at /data/redis,

```console
kubectl create -f docs/user-guide/walkthrough/pod-redis.yaml
```

wait until the pod is Running and Ready,

```console
$ kubectl get pods
NAME      READY     REASON    RESTARTS   AGE
storage   1/1       Running   0          1m
```

we then use `kubectl exec` to verify that the volume is mounted at /data/redis,

```console
$ kubectl exec storage ls /data
redis
```

## Using kubectl exec to open a bash terminal in a pod

After all, open a terminal in a pod is the most direct way to introspect the pod. Assuming the pod/storage is still running, run

```console
$ kubectl exec -ti storage -- bash
root@storage:/data#
```

This gets you a terminal.


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