Debugging efsl on embedded devices is a rather hard job, becauseyou can't just printf debug strings or watch memory maps easily. Because of that, core development has been performed under the Linux operating system. Under Linux, efsl can be compiled as library and used as a userspace filesystem handler. On Unix-style operating system (like Linux), all devices (usb stick, disc, \ldots)can be seen as a file, and as such been opened by efsl.\newline\newlineIn the following section, we will explain how to get started usingefsl as userspace filesystem handler. However, please note that the mainfocus for efsl is to support embedded systems, which usually don't evenhave 1\% of the memory you have on a PC. Accessing files on a FAT-filesystemwith efsl will be much slower than when accessing these files with the LinuxFAT kernel modules.\subsubsection{Download \& Compile}Let's get started:\begin{enumerate}	\item{Get the latest release of efsl on http://www.sf.net/projects/efsl/ 		and put it in your homedir}	\item{Unpack the library (tar xvfj efsl-version.tar.bz2)}	\item{Get inside the directory (cd $\sim$/efsl)}	\item{Create a symlink from \filename{Makefile-LINUX} to \filename{Makefile} 		(ln -s Makefile-LINUX Makefile)}	\item{Copy \filename{conf/config-sample-linux.h} to \filename{conf/config.h}		(cp conf/config-sample-linux.h conf/config.h)}	\item{Compile the library (make lib)}	\item{Find the compiled filesystem library (libefsl.a) in the current 		directory}\end{enumerate}If you got any errors with the steps above, please check that that you havethe following packages installed: tar, gcc, libgcc, binutils \& make.\subsubsection{Example}Since efsl itself is only a library, it's not supposed to do anythingout of the box, than just compile. To get started, we'll show here a smallexample program that opens a file on a disc/usb-stick/floppy that containsa FAT-filesystem and prints it's content to stdout.\newline\newlineFirst, create a new directory in which you put the compiled efsl-library(\filename{libefsl.a}) and create a new file called \filename{linuxtest.c} containing:\lstset{numbers=left, stepnumber=1, numberstyle=\small, numbersep=5pt, tabsize=4}\begin{lstlisting}	#include <stdio.h>	#include <efs.h> 	int main(void)	{		EmbeddedFileSystem efs;		EmbeddedFile file;		unsigned short i,e;		char buf[512];			if(efs_init(&efs,"/dev/sda")!=0){			printf("Could not open filesystem.\n");			return(-1);		}			if(file_fopen(&file,&efs.myFs,"group",'r')!=0){			printf("Could not open file.\n");			return(-2);		}		while(e=file_read(&file,512,buf)){			for(i=0;i<e;i++)			printf("\%c",buf[i]);		}			return(0);	}\end{lstlisting}$ $\newlineSome extra information on the code above:\begin{itemize}	\item{Line 1-2: The header files for stdio (used for printf) and efsl 		are included. When using the basic efsl functions, \filename{efs.h} is		the only header file of the efsl library that needs to be included.}	\item{Line 6: The object efs is created, this object will contain 		information about the hardware layer, the partition table and		the disc.}	\item{Line 7: The object file is created, this object will contain		information about the file that we will open on the efs-object.}	\item{Line 9: A buffer of 512 bytes is allocated. This buffer will	 	be filled by fread with data.}	\item{Line 11-14: Call of \code{efs\_init}, which will initialize the efs-object.		To this function we pass:		\begin{enumerate}			\item{A pointer to the efs-object.}			\item{A pointer to the file that contains the partition table /				file system (in this example, we select a device as file).}		\end{enumerate}		If this function returns 0, it means that a valid fat partition is		found on the device given. 		If no valid fat-filesystem is found, or the file does not exist, the 		function returns a negative value. In this example we then print an		error message and quit.}	\item{Line 16-19: Call of \code{file\_fopen()}, which will initialize the 		file-object. To this function we pass:		\begin{enumerate}			\item{A pointer to the file-object.}			\item{A pointer to the filesystem-object.} 			\item{A pointer to the filename.}			\item{A char containing the the mode (read, write, append).}		\end{enumerate}		If this function returns 0, it means the file has successfully been		opened for reading / writing / appending.		If the file could not be opened, a negative value is returned.	}	\item{Line 21-24: Call of \code{file\_read()}, which will read a given value of		bytes (in this example 512) from a file and put it's content into		the buffer passed (in this example called buf). This function returns		the amount of bytes read, so the while-loop will be executed as long		as there are bytes left in the file. The code inside the while-loop		will print all characters in the buffer.}\end{itemize}\subsubsection{Testing}So now let's test the program:\begin{enumerate}	\item{Compile the program 		(gcc -I/home/user/efsl/inc/ -I/home/user/efsl/conf -o linuxtest 		linuxtest.c -L./ -lefsl).}	\item{Insert a usb-disc, floppy, mp3-stick, \ldots with a valid 		fat-filesystem on it.}	\item{Mount the device, copy the file /etc/group on it's root dir \& umount		it.}	\item{Check that you have permission to access the device		(chown username /dev/sda*)}	\item{Run the program (./linuxtest)}\end{enumerate}