filename(3erl)
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 in\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:
It is not recommended to use this function. If possible, use the
beam_lib(3erl) module to extract 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\ ///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\ in"
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"
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"]
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