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NAME
filename - Filename manipulation functions.
DESCRIPTION
This module provides functions for analyzing and manipulating filenames. These functions
are designed so that the Erlang code can work on many different platforms with different
filename formats. With filename is meant all strings that can be used to denote a file.
The filename can be a short relative name like foo.erl, a long absolute name including a
drive designator, a directory name like D:\usr/local\bin\erl/lib\tools\foo.erl, or any
variations in between.
In Windows, all functions return filenames with forward slashes only, even if the
arguments contain backslashes. To normalize a filename by removing redundant directory
separators, use join/1.
The module supports raw filenames in the way that if a binary is present, or the filename
cannot be interpreted according to the return value of file:native_name_encoding/0, a raw
filename is also returned. For example, join/1 provided with a path component that is a
binary (and cannot be interpreted under the current native filename encoding) results in a
raw filename that is returned (the join operation is performed of course). For more
information about raw filenames, see the file module.
DATA TYPES
basedir_type() =
user_cache |
user_config |
user_data |
user_log |
site_config |
site_data
EXPORTS
absname(Filename) -> file:filename_all()
Types:
Filename = file:name_all()
Converts a relative Filename and returns an absolute name. No attempt is made to
create the shortest absolute name, as this can give incorrect results on file
systems that allow links.
Unix examples:
1> pwd().
"/usr/local"
2> filename:absname("foo").
"/usr/local/foo"
3> filename:absname("../x").
"/usr/local/../x"
4> filename:absname("/").
"/"
Windows examples:
1> pwd().
"D:/usr/local"
2> filename:absname("foo").
"D:/usr/local/foo"
3> filename:absname("../x").
"D:/usr/local/../x"
4> filename:absname("/").
"D:/"
absname(Filename, Dir) -> file:filename_all()
Types:
Filename = Dir = file:name_all()
Same as absname/1, except that the directory to which the filename is to be made
relative is specified in argument Dir.
absname_join(Dir, Filename) -> file:filename_all()
Types:
Dir = Filename = file:name_all()
Joins an absolute directory with a relative filename. Similar to join/2, but on
platforms with tight restrictions on raw filename length and no support for
symbolic links (read: VxWorks), leading parent directory components in Filename are
matched against trailing directory components in Dir so they can be removed from
the result - minimizing its length.
basedir(Type, Application) -> file:filename_all()
Types:
Type = basedir_type()
Application = string() | binary()
Equivalent to basedir(Type, Application, #{}).
basedir(Type, Application, Opts) -> file:filename_all()
Types:
Type = basedir_type()
Application = string() | binary()
Opts =
#{author => string() | binary(),
os => windows | darwin | linux,
version => string() | binary()}
Returns a suitable path, or paths, for a given type. If os is not set in Opts the
function will default to the native option, that is 'linux', 'darwin' or 'windows',
as understood by os:type/0. Anything not recognized as 'darwin' or 'windows' is
interpreted as 'linux'.
The options 'author' and 'version' are only used with 'windows' option mode.
* user_cache
The path location is intended for transient data files on a local machine.
On Linux: Respects the os environment variable XDG_CACHE_HOME.
1> filename:basedir(user_cache, "my_application", #{os=>linux}).
"/home/otptest/.cache/my_application"
1> filename:basedir(user_cache, "my_application", #{os=>darwin}).
"/home/otptest/Library/Caches/my_application"
1> filename:basedir(user_cache, "My App").
"c:/Users/otptest/AppData/Local/My App/Cache"
2> filename:basedir(user_cache, "My App").
"c:/Users/otptest/AppData/Local/My App/Cache"
3> filename:basedir(user_cache, "My App", #{author=>"Erlang"}).
"c:/Users/otptest/AppData/Local/Erlang/My App/Cache"
4> filename:basedir(user_cache, "My App", #{version=>"1.2"}).
"c:/Users/otptest/AppData/Local/My App/1.2/Cache"
5> filename:basedir(user_cache, "My App", #{author=>"Erlang",version=>"1.2"}).
"c:/Users/otptest/AppData/Local/Erlang/My App/1.2/Cache"
* user_config
The path location is intended for persistent configuration files.
On Linux: Respects the os environment variable XDG_CONFIG_HOME.
2> filename:basedir(user_config, "my_application", #{os=>linux}).
"/home/otptest/.config/my_application"
2> filename:basedir(user_config, "my_application", #{os=>darwin}).
"/home/otptest/Library/Application Support/my_application"
1> filename:basedir(user_config, "My App").
"c:/Users/otptest/AppData/Roaming/My App"
2> filename:basedir(user_config, "My App", #{author=>"Erlang", version=>"1.2"}).
"c:/Users/otptest/AppData/Roaming/Erlang/My App/1.2"
* user_data
The path location is intended for persistent data files.
On Linux: Respects the os environment variable XDG_DATA_HOME.
3> filename:basedir(user_data, "my_application", #{os=>linux}).
"/home/otptest/.local/my_application"
3> filename:basedir(user_data, "my_application", #{os=>darwin}).
"/home/otptest/Library/Application Support/my_application"
8> filename:basedir(user_data, "My App").
"c:/Users/otptest/AppData/Local/My App"
9> filename:basedir(user_data, "My App",#{author=>"Erlang",version=>"1.2"}).
"c:/Users/otptest/AppData/Local/Erlang/My App/1.2"
* user_log
The path location is intended for transient log files on a local machine.
On Linux: Respects the os environment variable XDG_CACHE_HOME.
4> filename:basedir(user_log, "my_application", #{os=>linux}).
"/home/otptest/.cache/my_application/log"
4> filename:basedir(user_log, "my_application", #{os=>darwin}).
"/home/otptest/Library/Caches/my_application"
12> filename:basedir(user_log, "My App").
"c:/Users/otptest/AppData/Local/My App/Logs"
13> filename:basedir(user_log, "My App",#{author=>"Erlang",version=>"1.2"}).
"c:/Users/otptest/AppData/Local/Erlang/My App/1.2/Logs"
* site_config
On Linux: Respects the os environment variable XDG_CONFIG_DIRS.
5> filename:basedir(site_data, "my_application", #{os=>linux}).
["/usr/local/share/my_application",
"/usr/share/my_application"]
6> os:getenv("XDG_CONFIG_DIRS").
"/etc/xdg/xdg-ubuntu:/usr/share/upstart/xdg:/etc/xdg"
7> filename:basedir(site_config, "my_application", #{os=>linux}).
["/etc/xdg/xdg-ubuntu/my_application",
"/usr/share/upstart/xdg/my_application",
"/etc/xdg/my_application"]
8> os:unsetenv("XDG_CONFIG_DIRS").
true
9> filename:basedir(site_config, "my_application", #{os=>linux}).
["/etc/xdg/my_application"]
5> filename:basedir(site_config, "my_application", #{os=>darwin}).
["/Library/Application Support/my_application"]
* site_data
On Linux: Respects the os environment variable XDG_DATA_DIRS.
10> os:getenv("XDG_DATA_DIRS").
"/usr/share/ubuntu:/usr/share/gnome:/usr/local/share/:/usr/share/"
11> filename:basedir(site_data, "my_application", #{os=>linux}).
["/usr/share/ubuntu/my_application",
"/usr/share/gnome/my_application",
"/usr/local/share/my_application",
"/usr/share/my_application"]
12> os:unsetenv("XDG_DATA_DIRS").
true
13> filename:basedir(site_data, "my_application", #{os=>linux}).
["/usr/local/share/my_application",
"/usr/share/my_application"]
5> filename:basedir(site_data, "my_application", #{os=>darwin}).
["/Library/Application Support/my_application"]
basename(Filename) -> file:filename_all()
Types:
Filename = file:name_all()
Returns the last component of Filename, or Filename itself if it does not contain
any directory separators.
Examples:
5> filename:basename("foo").
"foo"
6> filename:basename("/usr/foo").
"foo"
7> filename:basename("/").
[]
basename(Filename, Ext) -> file:filename_all()
Types:
Filename = Ext = file:name_all()
Returns the last component of Filename with extension Ext stripped. This function
is to be used to remove a (possible) specific extension. To remove an existing
extension when you are unsure which one it is, use rootname(basename(Filename)).
Examples:
8> filename:basename("~/src/kalle.erl", ".erl").
"kalle"
9> filename:basename("~/src/kalle.beam", ".erl").
"kalle.beam"
10> filename:basename("~/src/kalle.old.erl", ".erl").
"kalle.old"
11> filename:rootname(filename:basename("~/src/kalle.erl")).
"kalle"
12> filename:rootname(filename:basename("~/src/kalle.beam")).
"kalle"
dirname(Filename) -> file:filename_all()
Types:
Filename = file:name_all()
Returns the directory part of Filename.
Examples:
13> filename:dirname("/usr/src/kalle.erl").
"/usr/src"
14> filename:dirname("kalle.erl").
"."
5> filename:dirname("\\usr\\src/kalle.erl"). % Windows
"/usr/src"
extension(Filename) -> file:filename_all()
Types:
Filename = file:name_all()
Returns the file extension of Filename, including the period. Returns an empty
string if no extension exists.
Examples:
15> filename:extension("foo.erl").
".erl"
16> filename:extension("beam.src/kalle").
[]
find_src(Beam) ->
{SourceFile, Options} | {error, {ErrorReason, Module}}
find_src(Beam, Rules) ->
{SourceFile, Options} | {error, {ErrorReason, Module}}
Types:
Beam = Module | Filename
Filename = atom() | string()
Rules = [{BinSuffix :: string(), SourceSuffix :: string()}]
Module = module()
SourceFile = string()
Options = [Option]
Option =
{i, Path :: string()} |
{outdir, Path :: string()} |
{d, atom()}
ErrorReason = non_existing | preloaded | interpreted
Finds the source filename and compiler options for a module. The result can be fed
to compile:file/2 to compile the file again.
Warning:
This function is deprecated. Use filelib:find_source/1 instead for finding source
files.
If possible, use the beam_lib(3erl) module to extract the compiler options and the
abstract code format from the Beam file and compile that instead.
Argument Beam, which can be a string or an atom, specifies either the module name
or the path to the source code, with or without extension ".erl". In either case,
the module must be known by the code server, that is, code:which(Module) must
succeed.
Rules describes how the source directory can be found when the object code
directory is known. It is a list of tuples {BinSuffix, SourceSuffix} and is
interpreted as follows: if the end of the directory name where the object is
located matches BinSuffix, then the source code directory has the same name, but
with BinSuffix replaced by SourceSuffix. Rules defaults to:
[{"", ""}, {"ebin", "src"}, {"ebin", "esrc"}]
If the source file is found in the resulting directory, the function returns that
location together with Options. Otherwise the next rule is tried, and so on.
The function returns {SourceFile, Options} if it succeeds. SourceFile is the
absolute path to the source file without extension ".erl". Options includes the
options that are necessary to recompile the file with compile:file/2, but excludes
options such as report and verbose, which do not change the way code is generated.
The paths in options {outdir, Path} and {i, Path} are guaranteed to be absolute.
flatten(Filename) -> file:filename_all()
Types:
Filename = file:name_all()
Converts a possibly deep list filename consisting of characters and atoms into the
corresponding flat string filename.
join(Components) -> file:filename_all()
Types:
Components = [file:name_all()]
Joins a list of filename Components with directory separators. If one of the
elements of Components includes an absolute path, such as "/xxx", the preceding
elements, if any, are removed from the result.
The result is "normalized":
* Redundant directory separators are removed.
* In Windows, all directory separators are forward slashes and the drive letter
is in lower case.
Examples:
17> filename:join(["/usr", "local", "bin"]).
"/usr/local/bin"
18> filename:join(["a/b///c/"]).
"a/b/c"
6> filename:join(["B:a\\b///c/"]). % Windows
"b:a/b/c"
join(Name1, Name2) -> file:filename_all()
Types:
Name1 = Name2 = file:name_all()
Joins two filename components with directory separators. Equivalent to join([Name1,
Name2]).
nativename(Path) -> file:filename_all()
Types:
Path = file:name_all()
Converts Path to a form accepted by the command shell and native applications on
the current platform. On Windows, forward slashes are converted to backward
slashes. On all platforms, the name is normalized as done by join/1.
Examples:
19> filename:nativename("/usr/local/bin/"). % Unix
"/usr/local/bin"
7> filename:nativename("/usr/local/bin/"). % Windows
"\\usr\\local\\bin"
pathtype(Path) -> absolute | relative | volumerelative
Types:
Path = file:name_all()
Returns the path type, which is one of the following:
absolute:
The path name refers to a specific file on a specific volume.
Unix example: /usr/local/bin
Windows example: D:/usr/local/bin
relative:
The path name is relative to the current working directory on the current
volume.
Example: foo/bar, ../src
volumerelative:
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.
Windows example: D:bar.erl, /bar/foo.erl
rootname(Filename) -> file:filename_all()
rootname(Filename, Ext) -> file:filename_all()
Types:
Filename = Ext = file:name_all()
Removes a filename extension. rootname/2 works as rootname/1, except that the
extension is removed only if it is Ext.
Examples:
20> filename:rootname("/beam.src/kalle").
/beam.src/kalle"
21> filename:rootname("/beam.src/foo.erl").
"/beam.src/foo"
22> filename:rootname("/beam.src/foo.erl", ".erl").
"/beam.src/foo"
23> filename:rootname("/beam.src/foo.beam", ".erl").
"/beam.src/foo.beam"
safe_relative_path(Filename) -> unsafe | SafeFilename
Types:
Filename = SafeFilename = file:name_all()
Sanitizes the relative path by eliminating ".." and "." components to protect
against directory traversal attacks. Either returns the sanitized path name, or the
atom unsafe if the path is unsafe. The path is considered unsafe in the following
circumstances:
* The path is not relative.
* A ".." component would climb up above the root of the relative path.
Examples:
1> filename:safe_relative_path("dir/sub_dir/..").
"dir"
2> filename:safe_relative_path("dir/..").
[]
3> filename:safe_relative_path("dir/../..").
unsafe
4> filename:safe_relative_path("/abs/path").
unsafe
split(Filename) -> Components
Types:
Filename = file:name_all()
Components = [file:name_all()]
Returns a list whose elements are the path components of Filename.
Examples:
24> filename:split("/usr/local/bin").
["/","usr","local","bin"]
25> filename:split("foo/bar").
["foo","bar"]
26> filename:split("a:\\msdev\\include").
["a:/","msdev","include"]