<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE erlref SYSTEM "erlref.dtd">
<erlref>
<header>
<copyright>
<year>2003</year><year>2017</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>2003-01-21</date>
<rev>A</rev>
<file>filelib.xml</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
<seealso marker="kernel:file"><c>file</c></seealso> module.</p>
<p>This module does not support "raw" filenames (that is, files whose
names do not comply with the expected encoding). Such files are ignored
by the functions in this module.</p>
<p>For more information about raw filenames, see the
<seealso marker="kernel:file"><c>file</c></seealso> module.</p>
<note>
<p>
Functionality in this module generally assumes valid input and
does not necessarily fail on input that does not use a valid
encoding. You can validate the encoding of a filename using
<seealso marker="stdlib:filename#validate/1">filename:validate/1</seealso>.
</p>
<p>
File operations used to accept filenames containing
null characters (integer value zero). This caused
the name to be truncated at the first null character.
Filenames containing null characters inside the filename
are now <em>rejected</em> and will cause primitive
file operations fail.
</p>
</note>
<warning><p>
Currently null characters at the end of the filename
will be accepted by primitive file operations. Such
filenames are however still documented as invalid. The
implementation will also change in the future and
reject such filenames.
</p></warning>
</description>
<datatypes>
<datatype>
<name name="filename"/>
</datatype>
<datatype>
<name name="dirname"/>
</datatype>
<datatype>
<name name="dirname_all"/>
</datatype>
<datatype>
<name name="filename_all"/>
</datatype>
<datatype>
<name name="find_file_rule"/>
</datatype>
<datatype>
<name name="find_source_rule"/>
</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>Ensures that all parent directories for the specified 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 can be created. Returns <c>{error, <anno>Reason</anno>}</c> if
some parent directory does not exist and cannot be created.</p>
</desc>
</func>
<func>
<name name="file_size" arity="1"/>
<fsummary>Return the size in bytes of a file.</fsummary>
<desc>
<p>Returns the size of the specified file.</p>
</desc>
</func>
<func>
<name name="fold_files" arity="5"/>
<fsummary>Fold over all files matching a regular expression.</fsummary>
<desc>
<p>Folds function <c><anno>Fun</anno></c> over all (regular) files
<c><anno>F</anno></c> in directory <c><anno>Dir</anno></c> that match
the regular expression <c><anno>RegExp</anno></c> (for a description
of the allowed regular expressions,
see the <seealso marker="re"><c>re</c></seealso> module).
If <c><anno>Recursive</anno></c> is <c>true</c>, all subdirectories
to <c>Dir</c>
are processed. The regular expression matching is only done on
the filename without the directory part.</p>
<p>If Unicode filename translation is in effect and the file
system is transparent, filenames that cannot be
interpreted as Unicode can be encountered, in which case the
<c>fun()</c> must be prepared to handle raw filenames
(that is, binaries). If the regular expression contains
codepoints > 255, it does not match filenames that do
not conform to the expected character encoding (that is, are not
encoded in valid UTF-8).</p>
<p>For more information about raw filenames, see the
<seealso marker="kernel:file"><c>file</c></seealso> module.</p>
</desc>
</func>
<func>
<name name="is_dir" arity="1"/>
<fsummary>Test whether <c>Name</c> refers to a directory.</fsummary>
<desc>
<p>Returns <c>true</c> if <c><anno>Name</anno></c>
refers to a directory, otherwise <c>false</c>.</p>
</desc>
</func>
<func>
<name name="is_file" arity="1"/>
<fsummary>Test whether <c>Name</c> refers to a file or directory.
</fsummary>
<desc>
<p>Returns <c>true</c> if <c><anno>Name</anno></c>
refers to a file or a directory, otherwise <c>false</c>.</p>
</desc>
</func>
<func>
<name name="is_regular" arity="1"/>
<fsummary>Test whether <c>Name</c> refers to a (regular) file.</fsummary>
<desc>
<p>Returns <c>true</c> if <c><anno>Name</anno></c>
refers to a (regular) file, otherwise <c>false</c>.</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>Returns the date and time the specified file or directory was last
modified, or <c>0</c> 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>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 the following "wildcard characters" are interpreted in a special
way:</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> used as a single pattern 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 match a range of characters.
Example: <c>[A-Z]</c> matches 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 match.
Matching is case-sensitive, for example, "a" does not match "A".</p>
<p>Notice that multiple "*" characters are allowed
(as in Unix wildcards, but opposed to Windows/DOS wildcards).</p>
<p><em>Examples:</em></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, use the
following line:</p>
<code type="none">
filelib:wildcard("lib/*/ebin/*.beam").</code>
<p>To find <c>.erl</c> or <c>.hrl</c> in all applications <c>src</c>
directories, use either of the following lines:</p>
<code type="none">
filelib:wildcard("lib/*/src/*.?rl")</code>
<code type="none">
filelib:wildcard("lib/*/src/*.{erl,hrl}")</code>
<p>To find all <c>.hrl</c> files in <c>src</c> or <c>include</c>
directories:</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:</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:</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>Same as <seealso marker="#wildcard/1"><c>wildcard/1</c></seealso>,
except that <c><anno>Cwd</anno></c> is used instead of the working
directory.</p>
</desc>
</func>
<func>
<name name="find_file" arity="2"/>
<name name="find_file" arity="3"/>
<fsummary>Find a file relative to a given directory.</fsummary>
<desc>
<p>Looks for a file of the given name by applying suffix rules to
the given directory path. For example, a rule <c>{"ebin", "src"}</c>
means that if the directory path ends with <c>"ebin"</c>, the
corresponding path ending in <c>"src"</c> should be searched.</p>
<p>If <c><anno>Rules</anno></c> is left out or is an empty list, the
default system rules are used. See also the Kernel application
parameter <seealso
marker="kernel:kernel_app#source_search_rules"><c>source_search_rules</c></seealso>.</p>
</desc>
</func>
<func>
<name name="find_source" arity="1"/>
<fsummary>Find the source file for a given object file.</fsummary>
<desc>
<p>Equivalent to <c>find_source(Base, Dir)</c>, where <c>Dir</c> is
<c>filename:dirname(<anno>FilePath</anno>)</c> and <c>Base</c> is
<c>filename:basename(<anno>FilePath</anno>)</c>.</p>
</desc>
</func>
<func>
<name name="find_source" arity="2"/>
<name name="find_source" arity="3"/>
<fsummary>Find a source file relative to a given directory.</fsummary>
<desc>
<p>Applies file extension specific rules to find the source file for
a given object file relative to the object directory. For example,
for a file with the extension <c>.beam</c>, the default rule is to
look for a file with a corresponding extension <c>.erl</c> by
replacing the suffix <c>"ebin"</c> of the object directory path with
<c>"src"</c>.
The file search is done through <seealso
marker="#find_file/3"><c>find_file/3</c></seealso>. The directory of
the object file is always tried before any other directory specified
by the rules.</p>
<p>If <c><anno>Rules</anno></c> is left out or is an empty list, the
default system rules are used. See also the Kernel application
parameter <seealso
marker="kernel:kernel_app#source_search_rules"><c>source_search_rules</c></seealso>.</p>
</desc>
</func>
</funcs>
</erlref>
