<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
  <!ENTITY pytagsfs "<command>pytagsfs</command>">
]>

<refentry>

  <refentryinfo>
    <author><firstname>Forest</firstname><surname>Bond</surname></author>
    <address>forest@alittletooquiet.net</address>
    <copyright>
      <year>2007</year>
      <year>2008</year>
      <year>2009</year>
    </copyright>
    <date>2009-12-14</date>
  </refentryinfo>

  <refmeta>
    <refentrytitle>pytagsfs</refentrytitle>
    <manvolnum>1</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>pytagsfs</refname>
    <refpurpose>
      filesystem mapping media files to an arbitrary directory structure
    </refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis>
      &pytagsfs;
      <group choice="opt">OPTIONS</group>
      <arg choice="req"><replaceable>sourcedir</replaceable></arg>
      <arg choice="req"><replaceable>mountpoint</replaceable></arg>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>
    <para>
      pytagsfs is a FUSE filesystem that was designed to present multiple views
      of tagged media files.  For instance, a directory tree containing audio
      files could be mapped to a new directory structure organizing those same
      files by album, genre, release date, etc.
    </para>
    <para>
      To get a feel for what's possible, see
      <xref linkend="refsect1_examples"/>.
    </para>
    <para>
      Log messages are kept in a limited-size ring buffer in memory, and can be
      read from the virtual file named ".log", under the mount point root.
    </para>
  </refsect1>

  <refsect1>

    <title>Options</title>

    <variablelist>
      <varlistentry>
        <term><option>--version</option></term>
        <listitem><para>show version of program and exit</para></listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-h</option>, <option>--help</option></term>
        <listitem><para>show summary of options and exit</para></listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-f</option></term>
        <listitem><para>foreground operation</para></listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-d</option></term>
        <listitem><para>enable debug output (implies -f)</para></listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-s</option></term>
        <listitem><para>disable multi-threaded operation</para></listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-r</option></term>
        <listitem><para>mount read-only</para></listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-o</option> opt[,opt...]</term>
        <listitem><para>mount options</para></listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-o</option> format=FORMAT</term>
        <listitem>
          <para>
            format string for destination paths
            (see <xref linkend="refsect1_format_strings"/>)
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-o</option> srcfilter=EXPR</term>
        <listitem>
          <para>
            adds a source path filter; may be specified more than once
            (see <xref linkend="refsect1_path_filters"/>)
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-o</option> dstfilter=EXPR</term>
        <listitem>
          <para>
            adds a destination path filter; may be specified more than once
            (see <xref linkend="refsect1_path_filters"/>)
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-o</option> iocharset=ENCODING</term>
        <listitem>
          <para>mounted tree character encoding (default utf-8)</para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-o</option> source_iocharset=ENCODING</term>
        <listitem>
          <para>source directory character encoding (default utf-8)</para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-o</option> ro</term>
        <listitem>
          <para>synonym for -r (Linux)</para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-o</option> rdonly</term>
        <listitem>
          <para>synonym for -r (Darwin, FreeBSD, NetBSD, OpenBSD)</para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-o</option> allow_other</term>
        <listitem><para>allow access to other users</para></listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-o</option> allow_root</term>
        <listitem><para>allow access to root</para></listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-o</option> nonempty</term>
        <listitem><para>allow mounts over non-empty file/dir</para></listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-o</option> uid=UID</term>
        <listitem><para>set file owner</para></listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-o</option> gid=GID</term>
        <listitem><para>set file group</para></listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-o</option> verbosity=VERBOSITY</term>
        <listitem>
          <para>
            log level; must be one of "debug", "info", "warning", "error",
            "critical"; defaults to "warning"
          </para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-o</option> logsize=LOGSIZE</term>
        <listitem>
          <para>length of log file ring buffer</para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-o</option> debug</term>
        <listitem><para>synonym for -d</para></listitem>
      </varlistentry>
      <varlistentry>
        <term><option>-o</option> force_write_support</term>
        <listitem><para>
          Force write support on systems that are not known to have correct
          mmap semantics.  This option is dangerous and can lead to file
          corruption with some applications on some systems!
        </para></listitem>
      </varlistentry>
    </variablelist>

  </refsect1>

  <refsect1 id="refsect1_format_strings">

    <title>Format Strings</title>

    <para>
      A format string must be specified for each pytagsfs mount.  The format
      string specifies the structure of the virtual filesystem mount by defining
      a template for virtual paths.  For instance, the following format string
      defines a virtual filesystem layout that organizes media files by artist, 
      then by album, and, finally, by track name:
    </para>

    <screen>/%{artist}/%{album}/%{track}.%{extension}</screen>

    <refsect2>

      <title>Substitutions</title>

      <para>
        The format string should contain zero or more substitution sequences.
        Each such sequence begins with a percent sign (%).
      </para>

      <para>
        Substitution sequences may be specified in either long or short forms.
        Long-form substitution sequences are written as "%{KEY}", where KEY
        corresponds with a meta-data key.  The set of available keys varies
        from file to file, however, many media files feature some or all of
        the following long keys:
      </para>

      <simplelist>
        <member><constant>filename</constant>  name of the original file</member>
        <member><constant>parent</constant>  name of the original file's parent directory</member>
        <member><constant>extension</constant>  extension of the original file</member>
        <member><constant>tracknumber</constant>  track number; concise (like 7)</member>
        <member><constant>TRACKNUMBER</constant>  track number; two digits with leading zeros (like 07)</member>
        <member><constant>artist</constant>  artist</member>
        <member><constant>composer</constant> composer</member>
        <member><constant>title</constant>  track title</member>
        <member><constant>album</constant>  album title</member>
        <member><constant>year</constant>  year of release</member>
        <member><constant>genre</constant>  genre</member>
      </simplelist>

      <para>
        Short-form substitution sequences are written as "%X".  Each such
        sequence is an abbreviation for a long-form sequence, as indicated
        below:
      </para>

      <simplelist>
        <member><constant>f</constant>  filename</member>
        <member><constant>p</constant>  parent</member>
        <member><constant>e</constant>  extension</member>
        <member><constant>n</constant>  number</member>
        <member><constant>N</constant>  NUMBER</member>
        <member><constant>a</constant>  artist</member>
        <member><constant>c</constant>  composer</member>
        <member><constant>t</constant>  title</member>
        <member><constant>l</constant>  album</member>
        <member><constant>y</constant>  year</member>
        <member><constant>g</constant>  genre</member>
      </simplelist>

    </refsect2>

    <refsect2>

      <title>Modifiers</title>

      <para>
        Format strings can be further extended to perform string translations on
        parameters prior to substitution.  Such translations are indicated by
        the inclusion of a modifier character after the percent sign.  For
        instance, "%^a" indicates an all-caps version of the artist name, as
        does "%^{artist}".
      </para>

      <para>
        The full list of modifier characters follows:
      </para>

      <simplelist>
        <member><constant>^</constant>  UPPERCASE</member>
        <member><constant>_</constant>  lowercase</member>
        <member><constant>!</constant>  Title Case</member>
      </simplelist>

    </refsect2>

    <refsect2>

      <title>Conditional Expressions</title>

      <para>
        Normally, any file for which a parameter required by the format string
        cannot be determined is implicitly excluded from the resulting
        filesystem.  Conditionals can be used to express that these files should
        be included, but that those portions of the format string that cannot be
        rendered should be omitted or replaced.
      </para>

      <para>
        Two types of conditional expressions may be used: "if" expressions and
        "if-else" expressions.  The contents of an "if" expression are omitted
        unless all parameters within that expressions can be successfully
        evaluated.  An "if-else" expression is similar, except that, if the
        expression does not evaluate, an alternative will be used instead.  Use
        the following syntax:
      </para>

      <simplelist>
        <member>%?<replaceable>expr</replaceable>%?</member>
        <member>%?<replaceable>expr</replaceable>%:<replaceable>alt</replaceable>%?</member>
      </simplelist>

    </refsect2>

  </refsect1>

  <refsect1 id="refsect1_path_filters">

    <title>Path Filters</title>

    <para>
      Path filters can be used to limit the set of files presented by the
      filesystem using regular expressions.  Files are filtered by source path
      or by destination path, inclusively (limiting the set of paths to those
      that match the regular expression) or exclusively (limiting the set of
      paths to those that do <emphasis>not</emphasis> match the regular
      expression).
    </para>
    <para>
      Use the mount options <option>srcfilter</option> and
      <option>dstfilter</option> to filter by source path and destination path,
      respectively.  Filters are inclusive unless the filter parameter starts
      with an exclamation point, in which case the regular expression is assumed
      to be the part of the parameter following the exclamation point.
    </para>
    <para>
      Multiple filters of any kind may be used, and are applied in the order
      that they are specified on the command line.  See
      <xref linkend="refsect1_examples"/> for some sample filters.
    </para>

  </refsect1>

  <refsect1 id="refsect1_examples">
    <title>Examples</title>

    <para>
      View media files in <filename>src</filename>, with original filenames in a
      flat directory structure:
    </para>
    <screen>$ pytagsfs -o format='/%f' src mnt</screen>

    <para>
      View media files in <filename>src</filename> by album on
      <filename>mnt</filename>:
    </para>
    <screen>$ pytagsfs -o format='/%a/%f' src mnt</screen>

    <para>
      A more complex album-based view:
    </para>
    <screen>$ pytagsfs -o format='/%a - %l/%N %a - %t [%l].%e'</screen>

    <para>
      This is like above, but filters the result.  I use this to display my
      files by album, but exclude compilations (which I've tagged to include a
      hyphen in the album name, like "various - album"):
    </para>
    <screen>$ pytagsfs -o \
  format='/%a - %l/%N %a - %t [%l].%e',\
  dstfilter='!^/[^/]* - [^/]* - [^/]*/' \
  src albums</screen>

    <para>
      I use this to display the compilations:
    </para>
    <screen>$ pytagsfs -o \
  format='/%l/%N %a - %t [%l].%e',\
  dstfilter='^/[^/]* - [^/]*/' \
  src compilations</screen>

    <para>
      Maybe you only want to see files that start with "a" and end in ".mp3"?
    </para>
    <screen>$ pytagsfs -o \
  format='/%f',dstfilter='^/a',dstfilter='\.mp3$' \
  src mnt</screen>
  </refsect1>

  <refsect1>
    <title>Unmounting</title>
    <para>
      To unmount the filesystem on Linux use
      <citerefentry>
        <refentrytitle>fusermount</refentrytitle>
        <manvolnum>1</manvolnum>
      </citerefentry>:
    </para>
    <screen>
$ fusermount -u mnt
    </screen>
    <para>
      To unmount the filesystem on OS X or *BSD use
      <citerefentry>
        <refentrytitle>umount</refentrytitle>
        <manvolnum>1</manvolnum>
      </citerefentry>:
    </para>
    <screen>
$ umount mnt
    </screen>
  </refsect1>

  <refsect1>
    <title>Bugs</title>
    <para>
      Please report bugs on launchpad at
      http://launchpad.net/products/pytagsfs/+bugs.
    </para>
  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para>
      <citerefentry>
        <refentrytitle>fusermount</refentrytitle>
        <manvolnum>1</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>mount</refentrytitle>
        <manvolnum>8</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>umount</refentrytitle>
        <manvolnum>8</manvolnum>
      </citerefentry>,
      <citerefentry>
        <refentrytitle>pytags</refentrytitle>
        <manvolnum>1</manvolnum>
      </citerefentry>
    </para>
  </refsect1>

</refentry>