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<H1>filename</H1>
</CENTER>

<H3>MODULE</H3>
<DIV CLASS=REFBODY>
filename
</DIV>

<H3>MODULE SUMMARY</H3>
<DIV CLASS=REFBODY>
File Name Manipulation Functions
</DIV>

<H3>DESCRIPTION</H3>
<DIV CLASS=REFBODY>

<P>The module <CODE>filename</CODE> provides a number of useful 
functions for analyzing and manipulating file names. These functions are
designed so that the Erlang code can work on many different platforms with different formats for file names. With file name is meant all strings that can be 
used to denote a file. They can be short relative names like <CODE>foo.erl</CODE>, very long absolute name which include a drive designator and directory names like <CODE>D:\usr/local\bin\erl/lib\tools\foo.erl</CODE>, or any variations in between.
<P>In Windows, all functions return file names with forward slashes
only, even if the arguments contain back slashes.
Use the <CODE>join/1</CODE> function to normalize a file name by
removing redundant directory separators.


<P>All functions take either a flat list of characters (a &#34;string&#34;) or an
atom, or a deep list of strings and atoms.
The <CODE>file</CODE> module accepts filename in the same form.
The return value will always be a flat list of characters.

<P><STRONG>Types</STRONG>
<PRE>
filename = string() | atom() | [filename()]
</PRE>

</DIV>

<H3>EXPORTS</H3>

<P><A NAME="absname/1"><STRONG><CODE>absname(Filename) -&#62; Absname</CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE>Filename = filename()</CODE></STRONG><BR>
<STRONG><CODE>Absname = string()</CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P>      Converts a relative <CODE>Filename</CODE> and returns an absolute name.
         No attempt is made to create the shortest
         absolute name, because this can give incorrect results on 
         file systems which allow links.
        
<P>      Examples include:
        
<PRE>
Assume (for UNIX) current directory &#34;/usr/local&#34;
Assume (for WIN32) current directory &#34;D:/usr/local&#34;
  
(for UNIX):  absname(&#34;foo&#34;) -&#62; &#34;/usr/local/foo&#34;
(for WIN32): absname(&#34;foo&#34;) -&#62; &#34;D:/usr/local/foo&#34;
(for UNIX):  absname(&#34;../x&#34;) -&#62; &#34;/usr/local/../x&#34;
(for WIN32): absname(&#34;../x&#34;) -&#62; &#34;D:/usr/local/../x&#34;
(for UNIX):  absname(&#34;/&#34;) -&#62; &#34;/&#34;
(for WIN32): absname(&#34;/&#34;) -&#62; &#34;D:/&#34;
        
</PRE>

</DIV>

<P><A NAME="absname/2"><STRONG><CODE>absname(Filename, Directory) -&#62; Absname</CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE>Filename = filename()</CODE></STRONG><BR>
<STRONG><CODE>Directory = string()</CODE></STRONG><BR>
<STRONG><CODE>Absname = string()</CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P>      This function works like <CODE>absname/1</CODE>, except that
         the directory to which the file name should be made relative is given
         explicitly in the <CODE>Directory</CODE> argument.

</DIV>

<P><A NAME="absname_join/2"><STRONG><CODE>absname_join(Directory, Filename) -&#62; Absname</CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE>Filename = filename()</CODE></STRONG><BR>
<STRONG><CODE>Directory = string()</CODE></STRONG><BR>
<STRONG><CODE>Absname = string()</CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P>Joins an absolute directory with a relative
         filename. The same as join/2 but more magical. It also
         assumes that <CODE>Directory</CODE> is an absolute directory and
         <CODE>Filename</CODE> is a relative filename. Might crash
         otherwise.
        
<P>The magic consists in that on some platforms, namely they
         who have tight restrictions on raw filename length, leading
         parent directory components in <CODE>Filename</CODE> are matched
         against trailing directory components in <CODE>Directory</CODE> so
         they can be removed from the result - minimizing it's
         length.
        
<P>On the other hand, on platforms that support symbolic
         links such magic is magically not performed since it would
         not work.
        
</DIV>

<P><A NAME="basename/1"><STRONG><CODE>basename(Filename)</CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE>Filename = filename()</CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P>      Returns the part of the <CODE>Filename</CODE> after the 
         last directory separator,
         or the <CODE>Filename</CODE> itself if it has no separators.
        
<P>      Examples include:
        
<PRE>
basename(&#34;foo&#34;) -&#62; &#34;foo&#34;
basename(&#34;/usr/foo&#34;) -&#62; &#34;foo&#34;
basename(&#34;/&#34;) -&#62; []
        
</PRE>

</DIV>

<P><A NAME="basename/2"><STRONG><CODE>basename(Filename,Ext) -&#62; string()</CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE>Filename = Ext = filename()</CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P>Returns the last component of <CODE>Filename</CODE> with the
         extension <CODE>Ext</CODE> stripped. Use this function if you want to
         to remove an extension which might, or might not, be there.
         Use <CODE>rootname(basename(Filename))</CODE> if you want to remove an extension
         that exists, but you are not sure which one it is.
        
<P>      Examples include: 
        
<PRE>
basename(&#34;~/src/kalle.erl&#34;, &#34;.erl&#34;) -&#62; &#34;kalle&#34;
basename(&#34;~/src/kalle.beam&#34;, &#34;.erl&#34;) -&#62; &#34;kalle.beam&#34;
basename(&#34;~/src/kalle.old.erl&#34;, &#34;.erl&#34;) -&#62; &#34;kalle.old&#34;
rootname(basename(&#34;~/src/kalle.erl&#34;)) -&#62; &#34;kalle&#34;
rootname(basename(&#34;~/src/kalle.beam&#34;)) -&#62; &#34;kalle&#34;
        
</PRE>

</DIV>

<P><A NAME="dirname/1"><STRONG><CODE>dirname(Filename) -&#62; string()</CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE>Filename = filename()</CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P>Returns the directory part of <CODE>Filename</CODE>.

<P>Examples include:
         
<PRE>
dirname(&#34;/usr/src/kalle.erl&#34;) -&#62; &#34;/usr/src&#34;
dirname(&#34;kalle.erl&#34;) -&#62; &#34;.&#34;
On Win32:  
filename:dirname(&#34;\\usr\\src/kalle.erl&#34;) -&#62; &#34;/usr/src&#34;
          
</PRE>

</DIV>

<P><A NAME="extension/1"><STRONG><CODE>extension(Filename) -&#62; string() | []</CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE>Filename = filename()</CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P>Given a file name string <CODE>Filename</CODE>, this function returns the 
file extension including the period. Returns an empty list if there is no extension.
<P>Examples include:
<PRE>
extension(&#34;foo.erl&#34;) -&#62; &#34;.erl&#34;
extension(&#34;beam.src/kalle&#34;) -&#62; []
        
</PRE>

</DIV>

<P><A NAME="flatten/1"><STRONG><CODE>flatten(Filename) -&#62; string()</CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE>Filename = filename()</CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P>Converts a possibly deep list filename consisting of
         characters and atoms into the corresponding flat string
         filename.
</DIV>

<P><A NAME="join/1"><STRONG><CODE>join(Components) -&#62; string()</CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE>Components = [string()]</CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P>      Joins a list of file name <CODE>Components</CODE> with 
         directory separators. If one of the elements in the <CODE>Components</CODE>
         list includes an absolute path, for example &#34;/xxx&#34;, the preceding elements,
         if any, are removed from the result.
        
<P>The result of the <CODE>join</CODE> function is &#34;normalized&#34;:
<P>
<UL>

<LI>
There are no redundant directory separators.
</LI>


<LI>
In Windows, all directory separators are forward slashes and the drive
letter is in lower case.
</LI>


</UL>

<P>Examples include:
<PRE>
join(&#34;/usr/local&#34;, &#34;bin&#34;) -&#62; &#34;/usr/local/bin&#34;
join([&#34;/usr&#34;, &#34;local&#34;, &#34;bin&#34;]) -&#62; &#34;/usr/local/bin&#34;
join([&#34;a/b///c/&#34;] -&#62; &#34;a/b/c&#34;
join([&#34;B:a\\b///c/&#34;] -&#62; &#34;b:a/b/c&#34;  % On Windows only
        
</PRE>

</DIV>

<P><A NAME="join/2"><STRONG><CODE>join(Name1, Name2) -&#62; string()</CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE>Name1 = Name2 = string()</CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P>      Joins two file name components with directory separators. 
         Equivalent to <CODE>join([Name1,Name2]).</CODE>
        
</DIV>

<P><A NAME="nativename/1"><STRONG><CODE>nativename(Path) -&#62; string()</CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE>Path = string()</CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P>Converts a filename in <CODE>Path</CODE> to a form accepted by the command shell and native
applications on the current platform. On Windows, forward slashes
will be converted to backward slashes. On all platforms, the
name will be normalized as done by <CODE>join/1</CODE>.
<P>Example:
<PRE>
(on UNIX)  filename:nativename(&#34;/usr/local/bin/&#34;) -&#62; &#34;/usr/local/bin&#34;
(on Win32) filename:nativename(&#34;/usr/local/bin/&#34;) -&#62; &#34;\\usr\\local\\bin&#34;
</PRE>

</DIV>

<P><A NAME="pathtype/1"><STRONG><CODE>pathtype(Path) -&#62; absolute | relative | volumerelative</CODE></STRONG></A><BR>

<DIV CLASS=REFBODY>

<P>Returns one of <CODE>absolute</CODE>, <CODE>relative</CODE>, or 
         <CODE>volumerelative</CODE>.
         
<P>
<DL>

<DT>
<CODE>absolute</CODE>
</DT>

<DD>
The path name refers to a specific file on a specific volume.
         <BR>
Examples include:<BR>

<PRE>
on Unix
/usr/local/bin/
on Windows
D:/usr/local/bin
</PRE>

         
</DD>

<DT>
<CODE>relative</CODE>
</DT>

<DD>
         The path name is relative to the current working directory
         on the current volume. <BR>
Example:<BR>

<PRE>
foo/bar, ../src
</PRE>

         
</DD>

<DT>
<CODE>volumerelative</CODE>
</DT>

<DD>
         The path name is relative to the current 
         working directory on a specified volume,
         or it is a specific file on the current working volume.

<BR>
Examples include:
         <BR>

<PRE>
In Windows
D:bar.erl, /bar/foo.erl
/temp
            
</PRE>

         
</DD>

</DL>

</DIV>

<P><A NAME="rootname/1"><STRONG><CODE>rootname(Filename) -&#62; string()</CODE></STRONG></A><BR>
<A NAME="rootname/2"><STRONG><CODE>rootname(Filename, Ext) -&#62; string()</CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE>Filename = Ext = filename()</CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P>      <CODE>rootname/1</CODE> returns all characters in <CODE>Filename</CODE>, 
         except the extension.
        
<P>      <CODE>rootname/2</CODE> works as <CODE>rootname/1</CODE>, except that the 
         extension is removed only if it is <CODE>Ext</CODE>.
        
<P>Examples include:
        
<PRE>
rootname(&#34;/beam.src/kalle&#34;) -&#62; &#34;/beam.src/kalle&#34;
rootname(&#34;/beam.src/foo.erl&#34;) -&#62; &#34;/beam.src/foo&#34;
rootname(&#34;/beam.src/foo.erl&#34;,&#34;.erl&#34;) -&#62; &#34;/beam.src/foo&#34;
rootname(&#34;/beam.src/foo.beam&#34;,&#34;.erl&#34;) -&#62; &#34;/beam.src/foo.beam&#34;
        
</PRE>

</DIV>

<P><A NAME="split/1"><STRONG><CODE>split(Filename) -&#62; Components</CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE>Filename = filename()</CODE></STRONG><BR>
<STRONG><CODE>Components = [string()]</CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P>Returns a list whose elements are the path components of <CODE>Filename</CODE>.
        
<P>Examples include:
        
<PRE>
split(&#34;/usr/local/bin&#34;) -&#62; [&#34;/&#34;, &#34;usr&#34;, &#34;local&#34;, &#34;bin&#34;]
split(&#34;foo/bar&#34;) -&#62; [&#34;foo&#34;, &#34;bar&#34;]
split(&#34;a:\\msdev\\include&#34;) -&#62; [&#34;a:/&#34;, &#34;msdev&#34;, &#34;include&#34;]
        
</PRE>

</DIV>

<P><A NAME="find_src/1"><STRONG><CODE>find_src(Module) -&#62; {SourceFile, Options}</CODE></STRONG></A><BR>
<A NAME="find_src/2"><STRONG><CODE>find_src(Module, Rules) -&#62; {SourceFile, Options}</CODE></STRONG></A><BR>

<DIV CLASS=REFBODY><P>Types:
  <DIV CLASS=REFTYPES>
<P>
<STRONG><CODE>Module = atom() | string()</CODE></STRONG><BR>
<STRONG><CODE>SourceFile = string()</CODE></STRONG><BR>
<STRONG><CODE>Options = [CompilerOption]</CODE></STRONG><BR>
<STRONG><CODE>CompilerOption = {i, string()} | {outdir, string()} | {d, atom()}</CODE></STRONG><BR>

  </DIV>
</DIV>

<DIV CLASS=REFBODY>

<P>      Finds the source file name and compilation options for a compiled
         module. The result can be fed to <CODE>compile:file/2</CODE> in order to compile the
         file again.
        
<P>      The Module argument, which can be a string or an atom, specifies 
         either the module name or the path to the source code, with or 
         without the &#34;.erl&#34; extension. In either case, the module must be
         known by the code manager, i.e. <CODE>code:which/1</CODE> must succeed.
        
<P>      Rules describe how the source directory is found, when 
         the object code directory is known. Each rule is of the form
         <CODE>{BinSuffix, SourceSuffix}</CODE> and is interpreted as follows:
         If the end of the directory name where the object is located matches
         <CODE>BinSuffix</CODE>, then the suffix of the directory name is replaced by
         <CODE>SourceSuffix</CODE>.
         If the source file is found in the resulting
         directory, then the function returns that location together with 
         <CODE>Options</CODE>. Otherwise, the next rule is tried, and so on.
        
<P>      The function returns <CODE>{SourceFile, Options}</CODE>. 
         <CODE>SourceFile</CODE> is the absolute path to the source file 
         without the &#34;.erl&#34; extension. <CODE>Options</CODE>
         include the options which are necessary to compile the file
         with <CODE>compile:file/2</CODE>, but excludes options
         such as <CODE>report</CODE> or <CODE>verbose</CODE> which do not change
         the way code is generated.
         The paths in the <CODE>{outdir, Path}</CODE> and <CODE>{i, Path}</CODE>
         options are guaranteed to be absolute.

</DIV>

<H3>AUTHORS</H3>
<DIV CLASS=REFBODY>
Bjrn Gustavsson - support@erlang.ericsson.se<BR>

</DIV>
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<A HREF="http://www.erlang.se">Ericsson AB</A><BR>
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