fix:fatal error: 'stdlib.h' file not found

stdlib_h_file_not_found.sh

#!/bin/bash
echo "diagnose tool for problem: \"fatal error: 'stdlib.h' file not found\""
echo "by AndrewChoe(xgod@163.com)"
# reason:
# System header dir /usr/include has gone forever.
# However, some software may fail to build correctly against the SDK and require macOS headers to be installed in the base system under /usr/include

cat >/tmp/hello.c <<-"EOF"
#include <stdlib.h>
int main() {
     //ident with space Not Tab
     exit(0);
}
EOF
clang /tmp/hello.c

if [ $? -ne 0 ] ; then

	echo "oops, clang not work"
else
	echo "clang environment is good. bye"
	exit 0
fi

echo "--------------find all clang(include symbol link)------------"
sudo find /usr -name "clang"
echo ""
echo ""
	
echo "--------------find all clang real file (NOT sysmbol)---------"
sudo find /usr -name "clang" -type f
echo ""
echo ""

echo "--------------clang location:--------------"
command -v clang

echo ""
echo ""
echo "--------------clang search dirs--------------"
clang -print-search-dirs

echo ""
echo ""
echo "--------------clang symbol link:--------------"
readlink `command -v clang`



# for macOS 10.14
#open /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg

TIMELIMIT=10

# 4 seconds

echo "press key y with enter, will execute command: xcode-select --install"

read -t $TIMELIMIT variable <&1 # ^^^ # In this instance, "<&1" is needed for Bash 1.x and 2.x, # but unnecessary for Bash 3.x.


if [ -z "$variable" ] # Is null?
	then echo "you press nothing"
	exit 0

else

	#echo "variable = $variable"

	if [ "$variable" == "y" ] ; then
		xcode-select --install
	else 
		echo "you press $variable"
	fi
fi 

# brew doctor
# catalina work around

# brew unlink llvm@4
#Unlinking /usr/local/Cellar/llvm@4/4.0.1_1... 341 symlinks removed