Filename manipulation functions.
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.
Note!
Functionality in this module generally assumes valid input and does not necessarily fail on input that does not use a valid encoding, but may instead very likely produce invalid output.
File operations used to accept filenames containing null characters (integer value zero). This caused the name to be truncated and in some cases arguments to primitive operations to be mixed up. Filenames containing null characters inside the filename are now rejected and will cause primitive file operations to fail.
Warning!
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.
Functions
absname(Filename) -> file:filename_all()
Filename = file:name_all()
Converts a relative
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()
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
.
absname_join(Dir, Filename) -> file:filename_all()
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
are matched against trailing
directory components in
so they can be
removed from the result - minimizing its length.
basedir_path_type() =
user_cache | user_config | user_data | user_log
basedir_paths_type() = site_config | site_data
Equivalent to
basedir(
basedir_path_type() =
user_cache | user_config | user_data | user_log
basedir_paths_type() = site_config | site_data
basedir_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
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>
On Darwin:filename:basedir(user_cache, "my_application", #{os=>linux}).
"/home/otptest/.cache/my_application"1>
On Windows: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>
On Darwin:filename:basedir(user_config, "my_application", #{os=>linux}).
"/home/otptest/.config/my_application"2>
On Windows: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>
On Darwin:filename:basedir(user_data, "my_application", #{os=>linux}).
"/home/otptest/.local/my_application"3>
On Windows: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>
On Darwin:filename:basedir(user_log, "my_application", #{os=>linux}).
"/home/otptest/.cache/my_application/log"4>
On Windows: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>
On Darwin: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>
On Darwin: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()
Filename = file:name_all()
Returns the last component of
, or
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()
Filename = Ext = file:name_all()
Returns the last component of
with
extension
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()
Filename = file:name_all()
Returns the directory part of
.
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()
Filename = file:name_all()
Returns the file extension of
,
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}}
Beam = Module | Filename
Filename = atom() | string()
Module = module()
SourceFile = string()
Options = [Option]
Option =
{i, Path :: string()} |
{outdir, Path :: string()} |
{d, atom()}ErrorReason = non_existing | preloaded | interpreted
find_src(Beam, Rules) ->
{SourceFile, Options} | {error, {ErrorReason, Module}}
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(3)
module to extract the compiler options and the abstract code
format from the Beam file and compile that instead.
Argument
, 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(
must succeed.
describes how the source directory can be
found when the object code directory is known. It is a list of
tuples {
and
is interpreted as follows: if the end of the directory name where the
object is located matches
, then the
name created by replacing
with
is expanded by calling
filelib:wildcard/1
.
If a regular file is found among the matches, the function
returns that location together with
.
Otherwise the next rule is tried, and so on.
defaults
to:
[{"", ""}, {"ebin", "src"}, {"ebin", "esrc"}, {"ebin", "src/*"}, {"ebin", "esrc/*"}]
The function returns {
if it succeeds.
is the absolute path to the source
file without extension ".erl"
.
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,
and
{i, Path}
are guaranteed to be absolute.
flatten(Filename) -> file:filename_all()
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()
Components = [file:name_all()]
Joins a list of filename
with
directory separators.
If one of the elements of
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()
Name1 = Name2 = file:name_all()
Joins two filename components with directory separators.
Equivalent to join([
.
nativename(Path) -> file:filename_all()
Path = file:name_all()
Converts
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
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()
Filename = file:name_all()
rootname(Filename, Ext) -> file:filename_all()
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
.
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
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
Filename = file:name_all()
Components = [file:name_all()]
Returns a list whose elements are the path components of
.
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"]