Module Stdlib.Filename

Operations on file names.

val current_dir_name : string

The conventional name for the current directory (e.g. . in Unix).

val parent_dir_name : string

The conventional name for the parent of the current directory (e.g. .. in Unix).

val dir_sep : string

The directory separator (e.g. / in Unix).

  • since 3.11.2
val concat : string -> string -> string

concat dir file returns a file name that designates file file in directory dir.

val is_relative : string -> bool

Return true if the file name is relative to the current directory, false if it is absolute (i.e. in Unix, starts with /).

val is_implicit : string -> bool

Return true if the file name is relative and does not start with an explicit reference to the current directory (./ or ../ in Unix), false if it starts with an explicit reference to the root directory or the current directory.

val check_suffix : string -> string -> bool

check_suffix name suff returns true if the filename name ends with the suffix suff.

Under Windows ports (including Cygwin), comparison is case-insensitive, relying on String.lowercase_ascii. Note that this does not match exactly the interpretation of case-insensitive filename equivalence from Windows.

val chop_suffix : string -> string -> string

chop_suffix name suff removes the suffix suff from the filename name.

val chop_suffix_opt : suffix:string -> string -> string option

chop_suffix_opt ~suffix filename removes the suffix from the filename if possible, or returns None if the filename does not end with the suffix.

Under Windows ports (including Cygwin), comparison is case-insensitive, relying on String.lowercase_ascii. Note that this does not match exactly the interpretation of case-insensitive filename equivalence from Windows.

  • since 4.08
val extension : string -> string

extension name is the shortest suffix ext of name0 where:

  • name0 is the longest suffix of name that does not contain a directory separator;
  • ext starts with a period;
  • ext is preceded by at least one non-period character in name0.

If such a suffix does not exist, extension name is the empty string.

  • since 4.04
val remove_extension : string -> string

Return the given file name without its extension, as defined in Filename.extension. If the extension is empty, the function returns the given file name.

The following invariant holds for any file name s:

remove_extension s ^ extension s = s

  • since 4.04
val chop_extension : string -> string

Same as Filename.remove_extension, but raise Invalid_argument if the given name has an empty extension.

val basename : string -> string

Split a file name into directory name / base file name. If name is a valid file name, then concat (dirname name) (basename name) returns a file name which is equivalent to name. Moreover, after setting the current directory to dirname name (with Sys.chdir), references to basename name (which is a relative file name) designate the same file as name before the call to Sys.chdir.

This function conforms to the specification of POSIX.1-2008 for the basename utility.

val dirname : string -> string

See Filename.basename. This function conforms to the specification of POSIX.1-2008 for the dirname utility.

val null : string

null is "/dev/null" on POSIX and "NUL" on Windows. It represents a file on the OS that discards all writes and returns end of file on reads.

  • since 4.10.0
val temp_file : ?temp_dir:string -> string -> string -> string

temp_file prefix suffix returns the name of a fresh temporary file in the temporary directory. The base name of the temporary file is formed by concatenating prefix, then a suitably chosen integer number, then suffix. The optional argument temp_dir indicates the temporary directory to use, defaulting to the current result of Filename.get_temp_dir_name. The temporary file is created empty, with permissions 0o600 (readable and writable only by the file owner). The file is guaranteed to be different from any other file that existed when temp_file was called.

  • raises Sys_error

    if the file could not be created.

  • before 3.11.2

    no ?temp_dir optional argument

val open_temp_file : ?mode:open_flag list -> ?perms:int -> ?temp_dir:string -> string -> string -> string * out_channel

Same as Filename.temp_file, but returns both the name of a fresh temporary file, and an output channel opened (atomically) on this file. This function is more secure than temp_file: there is no risk that the temporary file will be modified (e.g. replaced by a symbolic link) before the program opens it. The optional argument mode is a list of additional flags to control the opening of the file. It can contain one or several of Open_append, Open_binary, and Open_text. The default is [Open_text] (open in text mode). The file is created with permissions perms (defaults to readable and writable only by the file owner, 0o600).

  • raises Sys_error

    if the file could not be opened.

  • before 4.03.0

    no ?perms optional argument

  • before 3.11.2

    no ?temp_dir optional argument

val get_temp_dir_name : unit -> string

The name of the temporary directory: Under Unix, the value of the TMPDIR environment variable, or "/tmp" if the variable is not set. Under Windows, the value of the TEMP environment variable, or "." if the variable is not set. The temporary directory can be changed with Filename.set_temp_dir_name.

  • since 4.00.0
val set_temp_dir_name : string -> unit

Change the temporary directory returned by Filename.get_temp_dir_name and used by Filename.temp_file and Filename.open_temp_file.

  • since 4.00.0
val temp_dir_name : string

The name of the initial temporary directory: Under Unix, the value of the TMPDIR environment variable, or "/tmp" if the variable is not set. Under Windows, the value of the TEMP environment variable, or "." if the variable is not set.

  • since 3.09.1
val quote : string -> string

Return a quoted version of a file name, suitable for use as one argument in a command line, escaping all meta-characters. Warning: under Windows, the output is only suitable for use with programs that follow the standard Windows quoting conventions.

val quote_command : string -> ?stdin:string -> ?stdout:string -> ?stderr:string -> string list -> string

quote_command cmd args returns a quoted command line, suitable for use as an argument to Sys.command, Unix.system, and the Unix.open_process functions.

The string cmd is the command to call. The list args is the list of arguments to pass to this command. It can be empty.

The optional arguments ?stdin and ?stdout and ?stderr are file names used to redirect the standard input, the standard output, or the standard error of the command. If ~stdin:f is given, a redirection < f is performed and the standard input of the command reads from file f. If ~stdout:f is given, a redirection > f is performed and the standard output of the command is written to file f. If ~stderr:f is given, a redirection 2> f is performed and the standard error of the command is written to file f. If both ~stdout:f and ~stderr:f are given, with the exact same file name f, a 2>&1 redirection is performed so that the standard output and the standard error of the command are interleaved and redirected to the same file f.

Under Unix and Cygwin, the command, the arguments, and the redirections if any are quoted using Filename.quote, then concatenated. Under Win32, additional quoting is performed as required by the cmd.exe shell that is called by Sys.command.

  • raises Failure

    if the command cannot be escaped on the current platform.

  • since 4.10.0