bash script to create a new shell script or library

new_shell_script.sh

#!/bin/bash
# Creates a new shell script or library
#
# Libraries should have a .sh file extension and ARE NOT executable.
# Commands should have no file extension and ARE executable by default.

function new_shell_script() {
	local file="${1:-"my_new_script"}"
	local filename
	local extension
	local script

	# create the file
	if [[ ! -r "${file}" ]]; then
	  touch "${file}"
	fi

	# prepend the opening hashbang and main function to the file
	# keep the text flush left here so it's not indented weirdly in the output
	script="
#!/bin/bash
#
# What this script does

function main() {
	echo 🆕 ${file} created!
}

main

"
	echo "${script}$(cat "${file}")" > tmpfile && mv tmpfile "${file}"

	# files with an ".sh" extension are assumed to be non-executable libraries
	filename=$(basename "${file}")
	extension="${filename##*.}"
	if [[ "sh" != "${extension}" ]]; then
	  chmod +x "${file}"
	fi

	# make sure it works now
	if [[ -x "${file}" ]]; then
	  ./"${file}"
	else
	  sh "${file}"
	fi
}