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# exec
<!---MARKER_GEN_START-->
Execute a command in a running container
### Aliases
`docker container exec`, `docker exec`
### Options
| Name | Type | Default | Description |
|:------------------------------------------|:---------|:--------|:-------------------------------------------------------|
| `-d`, `--detach` | | | Detached mode: run command in the background |
| `--detach-keys` | `string` | | Override the key sequence for detaching a container |
| [`-e`](#env), [`--env`](#env) | `list` | | Set environment variables |
| `--env-file` | `list` | | Read in a file of environment variables |
| `-i`, `--interactive` | | | Keep STDIN open even if not attached |
| [`--privileged`](#privileged) | | | Give extended privileges to the command |
| `-t`, `--tty` | | | Allocate a pseudo-TTY |
| `-u`, `--user` | `string` | | Username or UID (format: `<name\|uid>[:<group\|gid>]`) |
| [`-w`](#workdir), [`--workdir`](#workdir) | `string` | | Working directory inside the container |
<!---MARKER_GEN_END-->
## Description
The `docker exec` command runs a new command in a running container.
The command you specify with `docker exec` only runs while the container's
primary process (`PID 1`) is running, and it isn't restarted if the container
is restarted.
The command runs in the default working directory of the container.
The command must be an executable. A chained or a quoted command doesn't work.
- This works: `docker exec -it my_container sh -c "echo a && echo b"`
- This doesn't work: `docker exec -it my_container "echo a && echo b"`
## Examples
### Run `docker exec` on a running container
First, start a container.
```console
$ docker run --name mycontainer -d -i -t alpine /bin/sh
```
This creates and starts a container named `mycontainer` from an `alpine` image
with an `sh` shell as its main process. The `-d` option (shorthand for `--detach`)
sets the container to run in the background, in detached mode, with a pseudo-TTY
attached (`-t`). The `-i` option is set to keep `STDIN` attached (`-i`), which
prevents the `sh` process from exiting immediately.
Next, execute a command on the container.
```console
$ docker exec -d mycontainer touch /tmp/execWorks
```
This creates a new file `/tmp/execWorks` inside the running container
`mycontainer`, in the background.
Next, execute an interactive `sh` shell on the container.
```console
$ docker exec -it mycontainer sh
```
This starts a new shell session in the container `mycontainer`.
### <a name="env"></a> Set environment variables for the exec process (--env, -e)
Next, set environment variables in the current bash session.
The `docker exec` command inherits the environment variables that are set at the
time the container is created. Use the `--env` (or the `-e` shorthand) to
override global environment variables, or to set additional environment
variables for the process started by `docker exec`.
The following example creates a new shell session in the container `mycontainer`,
with environment variables `$VAR_A` set to `1`, and `$VAR_B` set to `2`.
These environment variables are only valid for the `sh` process started by that
`docker exec` command, and aren't available to other processes running inside
the container.
```console
$ docker exec -e VAR_A=1 -e VAR_B=2 mycontainer env
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
HOSTNAME=f64a4851eb71
VAR_A=1
VAR_B=2
HOME=/root
```
### <a name="privileged"></a> Escalate container privileges (--privileged)
See [`docker run --privileged`](container_run.md#privileged).
### <a name="workdir"></a> Set the working directory for the exec process (--workdir, -w)
By default `docker exec` command runs in the same working directory set when
the container was created.
```console
$ docker exec -it mycontainer pwd
/
```
You can specify an alternative working directory for the command to execute
using the `--workdir` option (or the `-w` shorthand):
```console
$ docker exec -it -w /root mycontainer pwd
/root
```
### Try to run `docker exec` on a paused container
If the container is paused, then the `docker exec` command fails with an error:
```console
$ docker pause mycontainer
mycontainer
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
482efdf39fac alpine "/bin/sh" 17 seconds ago Up 16 seconds (Paused) mycontainer
$ docker exec mycontainer sh
Error response from daemon: Container mycontainer is paused, unpause the container before exec
$ echo $?
1
```
|
