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Portable OS APIs


Path manipulation

local path = require'path'

Path manipulation library for Windows and UNIX paths. Parses all Windows path formats including long paths (\\?\), device paths (\\.\) and UNC paths.


path.platform -> s get the current platform
path.default_sep([pl]) -> s get the default separator for a platform
path.dev_alias(s) -> s|nil check if a path is a Windows device alias
path.type(s, [pl]) -> type get the path type
path.parse(s, [pl]) -> type, path[, drv|srv] break down a path to its basic parts
path.format(type, path, [drv|srv], pl) -> s put together a path from parsed parts
path.isabs(s, [pl]) -> is_abs, is_empty check if path is absolute, empty and valid
path.endsep(s, [pl], [sep], [dsep]) -> s, ok get/add/remove the ending separator
path.sep(s, [pl], [sep], ...) -> s detect/set the path separator
path.long(s, [pl], [long]) -> s|nil get/set a Windows long absolute path
path.file(s, [pl]) -> s get the last component of a path
path.nameext(s, [pl]) -> name, ext split path.file() into name and extension
path.ext(s, [pl]) -> s return only the extension from path.nameext()
path.dir(s, [pl]) -> s|nil get the path without the last component
path.gsplit(s, [pl], [full]) ->iter() -> s, sep iterate over path’s components
path.normalize(s, [pl], [opt]) -> s normalize a path in various ways
path.commonpath(s1, s2, [pl]) -> s|nil get the common prefix of two paths
path.depth(s, [pl]) -> n get the number of non-empty path components
path.combine(s1, s2, [pl], [sep], [dsep]) -> s|nil combine two paths if possible
path.abs(dir, s, [pl], [sep], [dsep]) -> s|nil,err convert relative path to absolute
path.rel(s, pwd, [pl], [sep], [dsep]) -> s|nil convert absolute path to relative
path.filename(s, [pl], [repl]) -> s|nil,err,code validate/make-valid filename

In the table above, pl is for platform and can be 'win' or 'unix' and defaults to the current platform.

path.platform -> s

Get the current platform which can be 'win' or 'unix'.

path.default_sep([pl]) -> s

Get the default separator for a platform which can be \ or /.

path.dev_alias(s) -> s|nil

Check if a path is a Windows device alias and if it is, return that alias.

path.type(s, [pl]) -> type

Get the path type which can be:

  • 'abs' - C:\path (Windows) or /path (UNIX)
  • 'rel' - a/b (Windows, UNIX)
  • 'abs_long' - \\?\C:\path (Windows)
  • 'abs_nodrive' - \path (Windows)
  • 'rel_drive' - C:a\b (Windows)
  • 'unc' - \\server\share\path (Windows)
  • 'unc_long' - \\?\UNC\server\share\path (Windows)
  • 'global' - \\?\path (Windows)
  • 'dev' - \\.\path (Windows)
  • 'dev_alias': CON, c:\path\nul.txt, etc. (Windows)

The empty path ('', which is technically invalid) comes off as type 'rel'.

The only paths that are portable between Windows and UNIX (Linux, OSX) without translation are type 'rel' paths using forward slashes only which are no longer than 259 bytes and which don’t contain any control characters (code 0-31) or the symbols <>:"|%?*\.

path.parse(s, [pl]) -> type, path[, drive|server]

Split a path into its local path component (i.e. the part containing only directories and files, eg. \path for C:\path or for \\server\path) and, depending on the path type, the drive letter or server name.

UNC paths are not validated and can have an empty server or share path.

path.format(type, path, [drive|server], [pl]) -> s

Put together a path from its broken-down components. No validation is done.

path.isabs(s, [pl]) -> is_abs, is_empty, is_valid

Check if a path is an absolute path or not, if it’s empty (i.e. root) or not, and if it’s valid or not.

Absolute paths for which their local path is '' are actually invalid (currently only incomplete UNC paths like \\server or \\? can be like that). For those paths is_valid is false.

path.endsep(s, [pl], [sep], [dsep]) -> s, success

Get/add/remove an ending separator of a path. If sep is nil or missing, the ending separator is returned (nil is returned if the path has no ending separator). If sep is true, '\\', '/', the path is returned with an ending separator added (true means use path’s own separator if it has one and failing that, use dsep or the default platform separator). If sep is false or '' the path without its ending separator is returned. success is false if trying to add or remove the ending separator from an empty path (note that even when that happens, the path can still be concatenated directly to a relative path and result in a valid path).

Multiple consecutive separators are treated as one in that they are returned together and are replaced together.

path.sep(s, [pl], [sep], [default_sep], [empty_names]) -> s

Detect or set the a path’s separator (for Windows paths only).

The arg sep can be nil (detect), true (set to default_sep), false (set to default_sep but only if both \ and / are found in the path, i.e. unify), '\\' or '/' (set specifically), or nil when empty_names is explicitly false (collapse duplicate separators only). default_sep defaults to the platform separator. Unless empty_names is true, consecutive separators are collapsed into the first one.

NOTE: Setting the separator as \ on a UNIX path may result in an invalid path because \ is a valid character in UNIX filenames.

path.long(s, [pl], [long]) -> s|nil

Get/set a Windows long absolute path (one starting with \\?\C:\). If long is nil, returns whether the path is a long or short Windows absolute path (returns nil for all other kinds of paths). Otherwise it converts the path, in which case long can be true (convert to long path), false (convert to short path) or 'auto' (convert to long style if too long, or to short style if short enough).

path.file(s, [pl]) -> s

Get the last component of a path. Returns '' if the path is empty or ends with a separator.

path.nameext(s, [pl]) -> name, ext

Split a path’s last component into the name and extension parts like so:

  • a.txt' -> 'a', 'txt'
  • '.bashrc' -> '.bashrc', nil
  • 'a' -> 'a', nil
  • 'a.' -> 'a', ''

path.ext(s, [pl]) -> s|nil

Return only the extension from path.nameext().

path.dir(s, [pl]) -> s

Get the path without the last component and separator. If the path ends with a separator then the whole path without the separator is returned. Multiple consecutive separators are treated as one. Returns nil for '', '.', 'C:', '/', 'C:\\' and \\server\. Returns '.' for simple filenames.

path.gsplit(s, [pl], [full]) -> iter() -> s, sep

Iterate over a path’s local components (that is excluding prefixes like \\server or C:). Pass true to the full arg to iterate over the whole unparsed path. For absolute paths, the first iteration is '', <root_separator>. Empty names are not iterated. Instead, consecutive separators are returned together. Concatenating all the iterated path components and separators always results in the exact original path.

path.normalize(s, [pl], [opt]) -> s

Normalize a path by removing . dirs, removing unnecessary .. dirs (careful: this changes where the path points to if there are symlinks on the path!), collapsing, normalizing or changing the separator (for Windows paths), converting between Windows long (\\?\, \\?\UNC\) and normal paths.

The opt arg controls the normalization:

  • dot_dirs - use true to keep . dirs.
  • dot_dot_dirs - use true to keep the .. dirs.
  • sep, default_sep, empty_names - args to pass to path.sep() (sep defaults to false, use 'leave' to avoid normalizing the separators)
  • endsep - sep arg to pass to path.endsep() (defaults to false, use 'leave' to avoid removing any end separator)
  • long - long arg to pass to path.long() (defaults to 'auto', use 'leave' to avoid converting between short and long paths)

NOTE: If normalization results in the empty relative path '', then '.' is returned instead.

path.commonpath(s1, s2, [pl]) -> s|nil

Get the common path prefix of two paths, including the end separator if both paths share it, or nil if the paths don’t have anything in common.

Note that path.commonpath('C:', 'C:\\', 'win') == nil because the paths are of different type even if they look like they share a common prefix.

BUG: The case-insensitive comparison for Windows doesn’t work with paths with non-ASCII characters because it’s made with string.lower(). Proper lowercase your paths before using this function, or patch string.lower() to support utf8 lowercasing. This is not an issue if both paths are in the original letter case (eg. they come from the same API).

path.depth(s, [pl]) -> n

Get the number of non-empty path components, excluding prefixes like C:\, \\server\, etc.

path.combine(s1, s2, [pl], [sep], [dsep]) -> s|nil,err

Combine two paths if possible (return nil, err if not). Supported combinations are between anything except dev_alias and rel paths, between abs_nodrive and rel_drive, and between rel_drive and abs or abs_long. When the paths can only be combined in one way, paths can be given in any order. The separator with which paths are combined is either sep or if sep is nil it’s detected and if that fails dsep or the default separator is used.

path.abs(dir, s, [pl], [sep], [dsep]) -> s|nil,err

Convert a relative path to an absolute path given a base dir (this is currently an alias of path.combine()).

path.rel(s, pwd, [pl], [sep], [dsep]) -> s|nil

Convert an absolute path into a relative path which is relative to pwd. Returns nil if the paths are of different types or don’t have a base path in common. The ending (back)slash is preserved if present.

path.filename(s, [pl], [repl]) -> s|nil,err,errcode

Validate a filename or apply a replacement function on it in order to make it valid. The repl function receives the problematic match and an error code indicating the problem which can be one of ’‘,’.’, ‘..’, ‘dev_alias’, ‘char’, ‘length’, ‘evil’ and it should return a replacement string or false/nil if it cannot do the replacement ('evil' errors should generally be replaced with '').

Last updated: 2 years ago | Edit on GitHub

Pkg type:Lua
Version: 5bda869
Last commit:
Author: Cosmin Apreutesei
License: Public Domain

Requires: none

Required by: dollar  fs  webb  x-widgets  gfonts  luapower  rs232  bundle