check_fs_writable.sh

#!/bin/bash

PROGNAME=`basename $0`
STAMP=`date +%s%N`

if [ $# -lt 1 ]; then
	echo "not enough args" >&2; exit 3 ;
elif [ $# -gt 2 ]; then
	echo "too many args" >&2; exit 3;
fi

while getopts ":hd:" FLAG; do
	case "${FLAG}" in
		d)
			DIRNAME=$OPTARG
			;;
		h)
			echo "USAGE: -h, -d to set a directory to check"
			exit 0
			;;
		[:?])
			echo "unknown option"
			echo "USAGE: -h, -d to set a directory to check"
			exit 0
			;;
	esac
done

if [[ -d $DIRNAME ]] && [[ -w $DIRNAME ]]; then
	TOUCHERR=`touch $DIRNAME/.$PROGNAME-$STAMP 2>&1`
	if [ $? -ne 0 ]; then
		echo "CRITICAL - cannot touch: $TOUCHERR"
		exit 2;
	fi
	ECHOERR=`echo "$STAMP" > $DIRNAME/.$PROGNAME-$STAMP 2>&1`
	if [ $? -ne 0 ]; then 
		echo "CRITICAL - cannot echo: $ECHOERR"
		exit 2;
	fi
	READBACK=`cat "$DIRNAME/.$PROGNAME-$STAMP" 2>&1`
	if [[ $READBACK -ne $STAMP ]]; then
		echo "CRITICAL - read back value is different: $READBACK"
		exit 2
	else
		echo "OK - set and read back file on $DIRNAME correctly"
		rm $DIRNAME/.$PROGNAME-$STAMP
		exit 0
	fi
else
	echo "CRITICAL - $DIRNAME is not a directory or not writable"
	exit 2
fi