CLI tool-installing wrapper

run

#!/bin/sh

if [ $# -lt 1 ]; then
    echo "Usage: $0 <tool> [args...]"
    exit 1
fi

tool="$1"
shift

if ! command -v "$tool" >/dev/null; then
    (apt update && apt install -y --no-install-recommends "$tool") <&-
fi

exec "$tool" "$@"

A wrapper for a tool that might not be installed, such as zstd. The tool will be installed if not present. Importantly, both args and stdin are properly passed to the wrapped tool even when installation happens. The magic is <&- which closes stdin for the installing subshell so that the original stdin is not consumed.

Mostly useful for e.g. CI where you want a particular tool installed on-demand but don't want to have to provide your own runner image.

Assumes the tool binary name and the APT package name are the same.