mirror of https://github.com/docker/cli.git
139 lines
4.3 KiB
Markdown
139 lines
4.3 KiB
Markdown
---
|
|
title: "exec"
|
|
description: "The exec command description and usage"
|
|
keywords: "command, container, run, execute"
|
|
---
|
|
|
|
# exec
|
|
|
|
```markdown
|
|
Usage: docker exec [OPTIONS] CONTAINER COMMAND [ARG...]
|
|
|
|
Run a command in a running container
|
|
|
|
Options:
|
|
-d, --detach Detached mode: run command in the background
|
|
--detach-keys Override the key sequence for detaching a container
|
|
-e, --env=[] Set environment variables
|
|
--env-file Read in a file of environment variables
|
|
--help Print usage
|
|
-i, --interactive Keep STDIN open even if not attached
|
|
--privileged Give extended privileges to the command
|
|
-t, --tty Allocate a pseudo-TTY
|
|
-u, --user Username or UID (format: <name|uid>[:<group|gid>])
|
|
-w, --workdir Working directory inside the container
|
|
```
|
|
|
|
## Description
|
|
|
|
The `docker exec` command runs a new command in a running container.
|
|
|
|
The command started using `docker exec` only runs while the container's primary
|
|
process (`PID 1`) is running, and it is not restarted if the container is
|
|
restarted.
|
|
|
|
COMMAND runs in the default directory of the container. If the underlying image
|
|
has a custom directory specified with the WORKDIR directive in its Dockerfile,
|
|
this directory is used instead.
|
|
|
|
COMMAND must be an executable. A chained or a quoted command does not work.
|
|
For example, `docker exec -it my_container sh -c "echo a && echo b"` works,
|
|
work, but `docker exec -it my_container "echo a && echo b"` does not.
|
|
|
|
## 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.
|
|
|
|
By default, 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 example below creates a new shell session in the container `mycontainer` with
|
|
environment variables `$VAR_A` and `$VAR_B` set to "1" and "2" respectively.
|
|
These environment variables are only valid for the `sh` process started by that
|
|
`docker exec` command, and are not 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="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
|
|
```
|