nicer kn for your bashrc

kn.sh

# kn <context> [namespace] lets you quickly change kubectl's context and
# optionally namespace. Tab completion is supported for both. If you just want
# to change namespace in the same context, you can use context ".".

function kn() {
    local context=$1
    local namespace=$2
    if [[ -z "$context" ]]; then
        echo "usage: kn <context> [namespace]" >&2
        return 1
    fi
    [[ "$context" = "." ]] && context=$(kubectl config current-context)
    if ! kubectl config get-contexts $context >/dev/null 2>&1; then
        echo "kn: context $context not found" >&2
        return 1
    fi
    if [[ -n "$namespace" ]]; then
        if ! kubectl --context="$context" get ns $namespace >/dev/null 2>&1; then
            echo "kn: namespace $namespace not found in context $context" >&2
            return 1
        fi
        kubectl config set-context $context --namespace $namespace
    fi
    if [[ $(kubectl config current-context) != $context ]]; then
        kubectl config use-context $context
    fi
}

function _kn() {
    local cur prev opts
    COMPREPLY=()
    cur="${COMP_WORDS[COMP_CWORD]}"
    prev="${COMP_WORDS[COMP_CWORD-1]}"
    opts=$(kubectl config get-contexts -o name)
    [[ "$prev" = "." ]] && prev=$(kubectl config current-context)
    if kubectl config get-contexts -o name | grep -q "^$prev$"
    then
        opts=$(kubectl "--context=$prev" get namespaces -o go-template --template="{{range .items}}{{.metadata.name}} {{end}}")
    fi
    COMPREPLY=($(compgen -W "${opts}" -- ${cur}))
    return 0
}
complete -F _kn kn