apheleia-from-project-root

#!/usr/bin/env bash

# USAGE: apheleia-from-project-root ROOT-FNAME CMD...
#
# If there is a file called ROOT-FNAME in the current directory or any
# parent directory up to the root of the filesystem, first change to
# that directory. If not, no worries, proceed without error. Then
# execute CMD with provided args.
#
# This can be used to make sure that a formatter is executed in the
# root directory of a project, if the file is within a project. For
# example, ROOT-FNAME could be ".git" or ".formatter.exs" or
# "package.json" or "pyproject.toml".

if (( "$#" <= 1 )); then
    echo >&2 "usage: apheleia-from-project-root ROOT-FNAME CMD..."
    exit 1
fi

# This function prints the name of the current directory if it
# contains a file or directory named after the first argument, or the
# parent directory if it contains such a file, or the parent's parent,
# and so on. If no such file is found it returns nonzero.
# https://unix.stackexchange.com/a/22215
find_upwards() {
    fname="$1"

    path="${PWD}"
    while [[ -n "${path}" && ! -e "${path}/${fname}" ]]; do
        path="${path%/*}"
    done
    [[ -n "${path}" ]] && echo "${path}"
}

if dir="$(find_upwards "$1")"; then
    cd -- "${dir}" || exit
fi

shift
exec "$@"