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<erlref>
  <header>
    <copyright>
      <year>2003</year><year>2013</year>
      <holder>Ericsson AB. All Rights Reserved.</holder>
    </copyright>
    <legalnotice>
      Licensed under the Apache License, Version 2.0 (the "License");
      you may not use this file except in compliance with the License.
      You may obtain a copy of the License at
 
          http://www.apache.org/licenses/LICENSE-2.0

      Unless required by applicable law or agreed to in writing, software
      distributed under the License is distributed on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      See the License for the specific language governing permissions and
      limitations under the License.
    
    </legalnotice>

    <title>filelib</title>
    <prepared>Bjorn Gustavsson</prepared>
    <responsible>Bjorn Gustavsson</responsible>
    <docno>1</docno>
    <approved>Kenneth Lundin</approved>
    <checked></checked>
    <date>03-01-21</date>
    <rev>A</rev>
    <file>filelib.sgml</file>
  </header>
  <module>filelib</module>
  <modulesummary>File utilities, such as wildcard matching of filenames</modulesummary>
  <description>
    <p>This module contains utilities on a higher level than the <c>file</c>
      module.</p>
    <p>This module does not support "raw" file names (i.e. files whose names
    do not comply with the expected encoding). Such files will be ignored
    by the functions in this module.</p>
    <p>For more information about raw file names, see the <seealso marker="kernel:file">file</seealso> module.</p>
  </description>

  <datatypes>
    <datatype>
      <name name="filename"/>
    </datatype>
    <datatype>
      <name name="dirname"/>
    </datatype>
    <datatype>
      <name name="dirname_all"/>
    </datatype>
    <datatype>
      <name name="filename_all"/>
    </datatype>
  </datatypes>

  <funcs>
    <func>
      <name name="ensure_dir" arity="1"/>
      <fsummary>Ensure that all parent directories for a file or directory exist.</fsummary>
      <desc>
        <p>The <c>ensure_dir/1</c> function ensures that all parent
          directories for the given file or directory name <c><anno>Name</anno></c>
          exist, trying to create them if necessary.</p>
        <p>Returns <c>ok</c> if all parent directories already exist
          or could be created, or <c>{error, <anno>Reason</anno>}</c> if some parent
          directory does not exist and could not be created for some
          reason.</p>
      </desc>
    </func>
    <func>
      <name name="file_size" arity="1"/>
      <fsummary>Return the size in bytes of the file.</fsummary>
      <desc>
        <p>The <c>file_size</c> function returns the size of the given file.</p>
      </desc>
    </func>
    <func>
      <name name="fold_files" arity="5"/>
      <fsummary>Fold over all files matching a regular expression.</fsummary>
      <desc>
        <p>The <c>fold_files/5</c> function folds the function
          <c><anno>Fun</anno></c> over all (regular) files <c><anno>F</anno></c> in the
          directory <c><anno>Dir</anno></c> that match the regular expression <c><anno>RegExp</anno></c>
	  (see the <seealso marker="re">re</seealso> module for a description
	  of the allowed regular expressions).
          If <c><anno>Recursive</anno></c> is true all sub-directories to <c>Dir</c>
          are processed. The regular expression matching is done on just
	  the filename without the directory part.</p>

	  <p>If Unicode file name translation is in effect and the file
	  system is completely transparent, file names that cannot be
	  interpreted as Unicode may be encountered, in which case the
	  <c>fun()</c> must be prepared to handle raw file names
	  (i.e. binaries). If the regular expression contains
	  codepoints beyond 255, it will not match file names that do
	  not conform to the expected character encoding (i.e. are not
	  encoded in valid UTF-8).</p>

	  <p>For more information about raw file names, see the 
          <seealso marker="kernel:file">file</seealso> module.</p>
      </desc>
    </func>
    <func>
      <name name="is_dir" arity="1"/>
      <fsummary>Test whether Name refer to a directory or not</fsummary>
      <desc>
        <p>The <c>is_dir/1</c> function returns <c>true</c> if <c><anno>Name</anno></c>
          refers to a directory, and <c>false</c> otherwise.</p>
      </desc>
    </func>
    <func>
      <name name="is_file" arity="1"/>
      <fsummary>Test whether Name refer to a file or directory.</fsummary>
      <desc>
        <p>The <c>is_file/1</c> function returns <c>true</c> if <c><anno>Name</anno></c>
          refers to a file or a directory, and <c>false</c> otherwise.</p>
      </desc>
    </func>
    <func>
      <name name="is_regular" arity="1"/>
      <fsummary>Test whether Name refer to a (regular) file.</fsummary>
      <desc>
        <p>The <c>is_regular/1</c> function returns <c>true</c> if <c><anno>Name</anno></c>
          refers to a file (regular file), and <c>false</c> otherwise.</p>
      </desc>
    </func>
    <func>
      <name name="last_modified" arity="1"/>
      <fsummary>Return the local date and time when a file was last modified.</fsummary>
      <desc>
        <p>The <c>last_modified/1</c> function returns the date and time the
          given file or directory was last modified, or 0 if the file
	  does not exist.</p>
      </desc>
    </func>
    <func>
      <name name="wildcard" arity="1"/>
      <fsummary>Match filenames using Unix-style wildcards.</fsummary>
      <desc>
        <p>The <c>wildcard/1</c> function returns a list of all files
          that match Unix-style wildcard-string <c><anno>Wildcard</anno></c>.</p>
        <p>The wildcard string looks like an ordinary filename, except
          that certain "wildcard characters" are interpreted in a special
          way. The following characters are special:
          </p>
        <taglist>
          <tag>?</tag>
          <item>
            <p>Matches one character.</p>
          </item>
          <tag>*</tag>
          <item>
            <p>Matches any number of characters up to the end of
              the filename, the next dot, or the next slash.</p>
          </item>
          <tag>**</tag>
          <item>
            <p>Two adjacent <c>*</c>'s used as a single pattern will
        match all files and zero or more directories and subdirectories.</p>
          </item>
          <tag>[Character1,Character2,...]</tag>
          <item>
            <p>Matches any of the characters listed. Two characters
	    separated by a hyphen will match a range of characters.
	    Example: <c>[A-Z]</c> will match any uppercase letter.</p>
          </item>
          <tag>{Item,...}</tag>
          <item>
            <p>Alternation. Matches one of the alternatives.</p>
          </item>
        </taglist>
        <p>Other characters represent themselves. Only filenames that
          have exactly the same character in the same position will match.
          (Matching is case-sensitive; i.e. "a" will not match "A").
          </p>
        <p>Note that multiple "*" characters are allowed
          (as in Unix wildcards, but opposed to Windows/DOS wildcards).
          </p>
        <p>Examples:</p>
        <p>The following examples assume that the current directory is the
          top of an Erlang/OTP installation.
          </p>
        <p>To find all <c>.beam</c> files in all applications, the following
          line can be used:</p>
        <code type="none">
    filelib:wildcard("lib/*/ebin/*.beam").        </code>
        <p>To find either <c>.erl</c> or <c>.hrl</c> in all applications
          <c>src</c> directories, the following</p>
        <code type="none">
    filelib:wildcard("lib/*/src/*.?rl")        </code>
        <p>or the following line</p>
        <code type="none">
    filelib:wildcard("lib/*/src/*.{erl,hrl}")        </code>
        <p>can be used.</p>
        <p>To find all <c>.hrl</c> files in either <c>src</c> or <c>include</c>
          directories, use:</p>
        <code type="none">
    filelib:wildcard("lib/*/{src,include}/*.hrl").        </code>
        <p>To find all <c>.erl</c> or <c>.hrl</c> files in either
          <c>src</c> or <c>include</c> directories, use:</p>
        <code type="none">
    filelib:wildcard("lib/*/{src,include}/*.{erl,hrl}")        </code>
        <p>To find all <c>.erl</c> or <c>.hrl</c> files in any
          subdirectory, use:</p>
        <code type="none">
    filelib:wildcard("lib/**/*.{erl,hrl}")        </code>
      </desc>
    </func>
    <func>
      <name name="wildcard" arity="2"/>
      <fsummary>Match filenames using Unix-style wildcards starting at a specified directory.</fsummary>
      <desc>
        <p>The <c>wildcard/2</c> function works like <c>wildcard/1</c>,
          except that instead of the actual working directory, <c><anno>Cwd</anno></c>
          will be used.</p>
      </desc>
    </func>
  </funcs>
</erlref>


