Kubectl exec
Internal
Overview
Execute a command in a container:
kubectl exec <pod-name|type/name> [-c <container>] [flags] -- <command> [args...] [options]
Do not surround the command and its flags/arguments with quotes unless that is how it would execute normally (i.e., do ls -t /usr, not "ls -t /usr").
The Role of '--' on Command Line
The '--' is a sequence of characters that signals to kubectl to stop scanning command line for its own flags and options (sequences that start with -). Everything after the double dash is a command that should be executed inside the pod.
Using the double dash is optional if the command to be executed inside the pod has no arguments that start with dash.
However, double dash is required if the command to be executed has its own command line arguments that start with dash. If the command you want to execute in the pod has any flags in common (e.g. -i), two dashes (--) must be used to separate the command's flags/arguments from kubectl's commands/arguments.
For example:
kubectl exec my-pod -it bash -c my-command
will fail because kubectl will interpret "-c" as a container name flag and try to look up "my-command" as a container in the pod - which will fail.
The correct command is:
kubectl exec my-pod -it -- bash -c my-command
which tells kubectl to execute "bash -c my-command" as command on the pod.
Example
Execute Commands Remotely into a Pod
Get the date on the target pod:
kubectl exec my-pod -- date
List the content of the container's root filesystem.
kubectl exec my-pod -- ls /
Delete a file on the container's root filesystem:
kubectl exec my-pod -- rm /tmp/some.file
If the target file does not exist, the kubectl returns a non-zero exit code:
kubectl exec my-pod -- rm /tmp/some.file; echo $?
rm: can't remove '/tmp/some.file': No such file or directory
command terminated with exit code 1
1
Note that globbing cannot be used with commands like rm or ls executed directly. A shell will be needed to interpret it:
kubectl exec my-pod -- sh -c 'rm /tmp/some-dir/*'
Interactive Commands
Start a bash into the container, switch to raw terminal mode, send stdin to the bash process in pod my-pod and sends stdout/stderr from 'bash' back to the client:
kubectl exec my-pod -it -- bash -il
Flags
-c,--container=
The name of the container to execute the command into. If omitted, the first container in the pod will be chosen.
-i,--stdin=false
Pass stdin to the container.
-t,--tty=false
Stdin is a TTY
--pod-running-timeout=
The length of time (like 5s, 2m, or 3h, higher than zero) to wait until at least one pod is running.