#!/bin/sh
set -e	# exit on first failed command
set -u	# exit if encounter never set variable


#--------------------------------------------------
# Checks the syntax of either a single shell script file,
# or every shell script file in a directory,
# or every shell script file in an entire directory tree.
#
# Usage:
#	sh checkSyntax.sh [-p path] [-R]
#
#	-p	if supplied, then requires a value that is either the path to a single .sh file
#		or the path to a directory;
#		if omitted, then the current working directory will be searched
#	
#	-R	if supplied, and if the path to be searched is a directory,
#		then also searches subdirectories for .sh files
#
# +++ KNOWN BUGS:
# --the find/while loop below screws up if any element in a path contains leading whitespace
#
# +++ In the future:
# --there are many more options from the find command (e.g. how symbolic links are handled--currently they are not followed)
# which might want to expose as command line arguments of this script.
#--------------------------------------------------


# Initialize option variables to preclude inheriting values from the environment:
opt_p="./"	# the path to search for the find command used below; default value is the current working directory
opt_R="-maxdepth 1"	# the maxdepth option for the find command used below; default value limit the search to just path itself (i.e. do not drill down into subdirectories)

# Parse command-line options:
while getopts 'p:R' option
do
	case "$option" in
	"p")
		opt_p="$OPTARG"
		;;
	"R")
		opt_R=""
		;;
	?)
		echo "Script will now quit with an exit code of 1"	# Note: if supply an invalid option, getopts should have already printed an error line by this point, so no need to duplicate it
		exit 1
		;;
	esac
done

# Find all the relevant .sh files and check their syntax:
find $opt_p $opt_R -type f -iname "*.sh" | while read shFile	# see Note below...
do
	( sh -n "$shFile" )	# sh -n will merely syntax check (never execute) shFile, and will print to stdout any errors found; encase in parentheses to execute in a subshell so that if a syntax error is found, which causes sh -n to have a non-zero exit code, then this parent shell does not see it; critical since it will stop executing (due to the set -e line at the top of the file) otherwise
done

# Note: originaly used this line instead of the first line above:
#	for shFile in `find $opt_p $opt_R -type f -iname "*.sh"`	# to understand this line, execute "man find"; was inspired by this script: Bounty: A recursive .M3U index generating shell script | debianHELP
# Dropped it because it fails on path elements which contain whitespace.
# The solution above is discussed here: https://www.unix.com/shell-programmin...e-between.html