Bash Tip - Use bash to implement like C's argc and argv

Test bash script capacity

I want to show how to write the advanced bash script with shift and array.
Feature:

• filter the arguments with '-' leading character as options
• the following inputs are the data arguments

Tested environments: - bash 4.3.48 x86_64-pc-linux-gnu ubuntu-16.04.4 LTS

	#!/usr/bin/env bash
	# Copyright (C) 2019 by Ben Wei <ben@juluos.org>
	# Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted.
	# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
	# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT,
	# OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
	# CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
	######
	# sample code of blog
	## tested with bash 4.3.48 x86_64-pc-linux-gnu ubuntu-16.04.4 LTS
	verbose=0
	clog()
	{
	if [ $verbose -gt 0 ]; then
	echo $@
	fi
	}
	syntax()
	{
	cat << EOF >/dev/stdout
	syntax: [options] <message 1> [message 2] [message 3]
	options -v verbose of clog
	EOF
	exit 1
	}
	while [ 1 ]; do
	if [[ "$1" =~ "-".* ]]; then
	if [ "$1" == "-v" ]; then
	verbose=1
	fi
	shift
	else
	break
	fi
	done
	if [ -z "$1" ]; then
	syntax
	fi
	arguments=("$1" "$2" "$3")
	argc=${#arguments[@]}
	if [ "$argc" -eq 0 ]; then
	syntax
	fi
	for ((i=0; i<${argc} ; i++)); do
	if [ "x${arguments[$i]}" = "x" ]; then continue; fi
	clog "input argument[$i]: ${arguments[$i]}"
	done
	exit 0

view raw bash_arguments_example.sh hosted with ❤ by GitHub

	# origin result
	bash bash_arguments_example.sh -v "a b" "ff 11"
	input argument[0]: a b
	input argument[1]: ff 11
	# with debuging option
	$ bash -x bash_arguments_example.sh -v "a b" "ff 11"
	+ verbose=0
	+ '[' 1 ']'
	+ [[ -v =~ -.* ]]
	+ '[' -v == -v ']'
	+ verbose=1
	+ shift
	+ '[' 1 ']'
	+ [[ a b =~ -.* ]]
	+ break
	+ '[' -z 'a b' ']'
	+ arguments=("$1" "$2" "$3")
	+ argc=3
	+ '[' 3 -eq 0 ']'
	+ (( i=0 ))
	+ (( i<3 ))
	+ '[' 'xa b' = x ']'
	+ clog 'input argument[0]: a b'
	+ '[' 1 -gt 0 ']'
	+ echo input 'argument[0]:' a b
	input argument[0]: a b
	+ (( i++ ))
	+ (( i<3 ))
	+ '[' 'xff 11' = x ']'
	+ clog 'input argument[1]: ff 11'
	+ '[' 1 -gt 0 ']'
	+ echo input 'argument[1]:' ff 11
	input argument[1]: ff 11
	+ (( i++ ))
	+ (( i<3 ))
	+ '[' x = x ']'
	+ continue
	+ (( i++ ))
	+ (( i<3 ))
	+ exit 0

view raw executed result hosted with ❤ by GitHub