podman-exec(1)

NAME
podman-exec - Execute a command in a running container

SYNOPSIS
podman exec [options] container command [arg ...]

podman container exec [options] container command [arg ...]

DESCRIPTION
podman exec executes a command in a running container.

OPTIONS

  --cidfile=file
Read the ID of the target container from the specified file.

  --detach, -d
Start the exec session, but do not attach to it. The command runs in the background, and the exec session is automatically removed when it completes. The podman exec command prints the ID of the exec session and exits immediately after it starts.

  --detach-keys=sequence
Specify the key sequence for detaching a container. Format is a single character [a-Z] or one or more ctrl-<value> characters where <value> is one of: a-z, @, ^, [, , or _. Specifying "" disables this feature. The default is ctrl-p,ctrl-q.

This option can also be set in containers.conf(5) file.

  --env, -e=env
Set environment variables.

This option allows arbitrary environment variables that are available for the process to be launched inside of the container. If an environment variable is specified without a value, Podman checks the host environment for a value and set the variable only if it is set on the host. As a special case, if an environment variable ending in * is specified without a value, Podman searches the host environment for variables starting with the prefix and adds those variables to the container.

  --env-file=file
Read in a line-delimited file of environment variables.

  --interactive, -i
When set to true, make stdin available to the contained process. If false, the stdin of the contained process is empty and immediately closed.

If attached, stdin is piped to the contained process. If detached, reading stdin will block until later attached.

Caveat: Podman will consume input from stdin as soon as it becomes available, even if the contained process doesn't request it.

  --latest, -l
Instead of providing the container name or ID, use the last created container. Note: the last started container can be from other users of Podman on the host machine. (This option is not available with the remote Podman client, including Mac and Windows (excluding WSL2) machines)

  --no-session
Do not create a database session for the exec process. This can improve performance but the exec session will not be visible to other podman commands.

  --preserve-fd=FD1[,FD2,...]
Pass down to the process the additional file descriptors specified in the comma separated list. It can be specified multiple times. This option is only supported with the crun OCI runtime. It might be a security risk to use this option with other OCI runtimes.

(This option is not available with the remote Podman client, including Mac and Windows (excluding WSL2) machines)

  --preserve-fds=N
Pass down to the process N additional file descriptors (in addition to 0, 1, 2). The total FDs are 3+N. (This option is not available with the remote Podman client, including Mac and Windows (excluding WSL2) machines)

  --privileged
Give extended privileges to this container. The default is false.

By default, Podman containers are unprivileged (=false) and cannot, for example, modify parts of the operating system. This is because by default a container is only allowed limited access to devices. A "privileged" container is given the same access to devices as the user launching the container, with the exception of virtual consoles (/dev/tty\d+) when running in systemd mode (--systemd=always).

A privileged container turns off the security features that isolate the container from the host. Dropped Capabilities, limited devices, read-only mount points, Apparmor/SELinux separation, and Seccomp filters are all disabled. Due to the disabled security features, the privileged field should almost never be set as containers can easily break out of confinement.

Containers running in a user namespace (e.g., rootless containers) cannot have more privileges than the user that launched them.

  --tty, -t
Allocate a pseudo-TTY. The default is false.

When set to true, Podman allocates a pseudo-tty and attach to the standard input of the container. This can be used, for example, to run a throwaway interactive shell.

NOTE: The --tty flag prevents redirection of standard output. It combines STDOUT and STDERR, it can insert control characters, and it can hang pipes. This option is only used when run interactively in a terminal. When feeding input to Podman, use -i only, not -it.

  --user, -u=user[:group]
Sets the username or UID used and, optionally, the groupname or GID for the specified command. Both user and group may be symbolic or numeric.

Without this argument, the command runs as the user specified in the container image. Unless overridden by a USER command in the Containerfile or by a value passed to this option, this user generally defaults to root.

When a user namespace is not in use, the UID and GID used within the container and on the host match. When user namespaces are in use, however, the UID and GID in the container may correspond to another UID and GID on the host. In rootless containers, for example, a user namespace is always used, and root in the container by default corresponds to the UID and GID of the user invoking Podman.

  --workdir, -w=dir
Working directory inside the container.

The default working directory for running binaries within a container is the root directory (/). The image developer can set a different default with the WORKDIR instruction. The operator can override the working directory by using the -w option.

Exit Status
The exit code from podman exec gives information about why the command within the container failed to run or why it exited. When podman exec exits with a non-zero code, the exit codes follow the chroot standard, see below:

125 The error is with Podman itself
    $ podman exec --foo ctrID /bin/sh; echo $?
    Error: unknown flag: --foo
    125

126 The contained command cannot be invoked
    $ podman exec ctrID /etc; echo $?
    Error: container_linux.go:346: starting container process caused "exec: \"/etc\": permission denied": OCI runtime error
    126

127 The contained command cannot be found
    $ podman exec ctrID foo; echo $?
    Error: container_linux.go:346: starting container process caused "exec: \"foo\": executable file not found in $PATH": OCI runtime error
    127

Exit code The contained command exit code
    $ podman exec ctrID /bin/sh -c 'exit 3'; echo $?
    3

EXAMPLES
Execute command in selected container with a stdin and a tty allocated:
    $ podman exec -it ctrID ls

Execute command with the overridden working directory in selected container with a stdin and a tty allocated:
    $ podman exec -it -w /tmp myCtr pwd

Execute command as the specified user in selected container:
    $ podman exec --user root ctrID ls

Execute command but do not attach to the exec session leaving the command running in the background:
    $ podman exec -d ctrID find /path/to/search -name yourfile

SEE ALSO
podman(1), podman-run(1)

HISTORY
December 2017, Originally compiled by Brent Baudebbaude@redhat.com ⟨mailto:bbaude@redhat.com⟩