docker-container-exec - Run a command in a running container
docker container exec [OPTIONS] CONTAINER COMMAND [ARG...]
Run a process in a running container.
The command started using docker exec will only run while the
container's primary process (PID 1) is running, and will not be
restarted if the container is restarted.
If the container is paused, then the docker exec command will wait
until the container is unpaused, and then run
privileged gives the process extended Linux capabilities
<http://man7.org/linux/man-pages/man7/capabilities.7.html> when running
in a container.
Without this flag, the process run by docker exec in a running
container has the same capabilities as the container, which may be
limited. Set --privileged to give all capabilities to the process.
user sets the username or UID used and optionally the groupname or GID
for the specified command.
The followings examples are all valid:
--user [user | user:group | uid | uid:gid | user:gid | uid:group ]
Without this argument the command will be run as root in the container.
The exit code from docker exec gives information about why the
container failed to exec or why it exited. When docker exec exits with
a non-zero code, the exit codes follow the chroot standard, see below:
126 if the contained command cannot be invoked
$ docker exec busybox /etc; echo $?
# exec: "/etc": permission denied
docker: Error response from daemon: Contained command could not be invoked
127 if the contained command cannot be found
$ docker exec busybox foo; echo $?
# exec: "foo": executable file not found in $PATH
docker: Error response from daemon: Contained command not found or does not exist
Exit code of contained command otherwise
$ docker exec busybox /bin/sh -c 'exit 3'
Detached mode: run command in the background
Override the key sequence for detaching a container
Set environment variables
help for exec
Keep STDIN open even if not attached
Give extended privileges to the command
Allocate a pseudo-TTY
Username or UID (format: <name|uid>[:<group|gid>])
Working directory inside the container
Docker Community May 2019 DOCKER(1)