.. index:: osp
.. _osp/0:

**protocol**

``osp``
=======

Portable operating-system access protocol.

| **Author:** Paulo Moura
| **Version:** 1.24
| **Date:** 2019/5/7

| **Compilation flags:**
|    ``static``


(no dependencies on other entities)


Public interface
----------------

.. raw:: html

   <div id="pid/1"> </div>

.. index:: pid/1
.. _osp/0::pid/1:

``pid/1``
^^^^^^^^^

Returns the process identifier of the running process.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``pid(PID)``
| **Mode and number of proofs:**
|    ``pid(-integer)`` - ``one``


.. raw:: html

   <div id="shell/2"> </div>

.. index:: shell/2
.. _osp/0::shell/2:

``shell/2``
^^^^^^^^^^^

Runs an operating-system shell command and returns its exit status.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``shell(Command,Status)``
| **Mode and number of proofs:**
|    ``shell(+atom,-integer)`` - ``one``


.. raw:: html

   <div id="shell/1"> </div>

.. index:: shell/1
.. _osp/0::shell/1:

``shell/1``
^^^^^^^^^^^

Runs an operating-system shell command.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``shell(Command)``
| **Mode and number of proofs:**
|    ``shell(+atom)`` - ``zero_or_one``


.. raw:: html

   <div id="absolute_file_name/2"> </div>

.. index:: absolute_file_name/2
.. _osp/0::absolute_file_name/2:

``absolute_file_name/2``
^^^^^^^^^^^^^^^^^^^^^^^^

Expands a file name to an absolute file path. An environment variable at the beginning of the file name is also expanded.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``absolute_file_name(File,Path)``
| **Mode and number of proofs:**
|    ``absolute_file_name(+atom,-atom)`` - ``one``


.. raw:: html

   <div id="decompose_file_name/3"> </div>

.. index:: decompose_file_name/3
.. _osp/0::decompose_file_name/3:

``decompose_file_name/3``
^^^^^^^^^^^^^^^^^^^^^^^^^

Decomposes a file name into its directory (which always ends with a slash; "./" is returned if absent) and its basename (that can be the empty atom).

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``decompose_file_name(File,Directory,Basename)``
| **Mode and number of proofs:**
|    ``decompose_file_name(+atom,?atom,?atom)`` - ``one``


.. raw:: html

   <div id="decompose_file_name/4"> </div>

.. index:: decompose_file_name/4
.. _osp/0::decompose_file_name/4:

``decompose_file_name/4``
^^^^^^^^^^^^^^^^^^^^^^^^^

Decomposes a file name into its directory (which always ends with a slash; "./" is returned if absent), name (that can be the empty atom), and extension (which starts with a "." when defined; the empty atom otherwise).

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``decompose_file_name(File,Directory,Name,Extension)``
| **Mode and number of proofs:**
|    ``decompose_file_name(+atom,?atom,?atom,?atom)`` - ``one``


.. raw:: html

   <div id="make_directory/1"> </div>

.. index:: make_directory/1
.. _osp/0::make_directory/1:

``make_directory/1``
^^^^^^^^^^^^^^^^^^^^

Makes a new directory. Succeeds if the directory already exists.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``make_directory(Directory)``
| **Mode and number of proofs:**
|    ``make_directory(+atom)`` - ``one``


.. raw:: html

   <div id="make_directory_path/1"> </div>

.. index:: make_directory_path/1
.. _osp/0::make_directory_path/1:

``make_directory_path/1``
^^^^^^^^^^^^^^^^^^^^^^^^^

Makes a new directory creating all the intermediate directories if necessary. Succeeds if the directory already exists.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``make_directory_path(Directory)``
| **Mode and number of proofs:**
|    ``make_directory_path(+atom)`` - ``one``


.. raw:: html

   <div id="delete_directory/1"> </div>

.. index:: delete_directory/1
.. _osp/0::delete_directory/1:

``delete_directory/1``
^^^^^^^^^^^^^^^^^^^^^^

Deletes an empty directory.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``delete_directory(Directory)``
| **Mode and number of proofs:**
|    ``delete_directory(+atom)`` - ``one``


.. raw:: html

   <div id="change_directory/1"> </div>

.. index:: change_directory/1
.. _osp/0::change_directory/1:

``change_directory/1``
^^^^^^^^^^^^^^^^^^^^^^

Changes current working directory.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``change_directory(Directory)``
| **Mode and number of proofs:**
|    ``change_directory(+atom)`` - ``one``


.. raw:: html

   <div id="working_directory/1"> </div>

.. index:: working_directory/1
.. _osp/0::working_directory/1:

``working_directory/1``
^^^^^^^^^^^^^^^^^^^^^^^

Current working directory.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``working_directory(Directory)``
| **Mode and number of proofs:**
|    ``working_directory(?atom)`` - ``zero_or_one``


.. raw:: html

   <div id="directory_files/2"> </div>

.. index:: directory_files/2
.. _osp/0::directory_files/2:

``directory_files/2``
^^^^^^^^^^^^^^^^^^^^^

Returns a list of all files (including directories, regular files, and hidden directories and files) in a directory. File paths are relative to the directory.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``directory_files(Directory,Files)``
| **Mode and number of proofs:**
|    ``directory_files(+atom,-list(atom))`` - ``one``


.. raw:: html

   <div id="directory_files/3"> </div>

.. index:: directory_files/3
.. _osp/0::directory_files/3:

``directory_files/3``
^^^^^^^^^^^^^^^^^^^^^

Returns a filtered list of files. Filters: paths/1 - relative/absolute, type/1 - all/regular/directory, extensions/1 - list, prefixes/1 - list, suffixes/1 - list, dot_files/1 - boolean. Invalid options ignored. Defaults equivalent to directory_files/2.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``directory_files(Directory,Files,Options)``
| **Mode and number of proofs:**
|    ``directory_files(+atom,-list(atom),+list(compound))`` - ``one``


.. raw:: html

   <div id="directory_exists/1"> </div>

.. index:: directory_exists/1
.. _osp/0::directory_exists/1:

``directory_exists/1``
^^^^^^^^^^^^^^^^^^^^^^

True if the specified directory exists (irrespective of directory permissions).

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``directory_exists(Directory)``
| **Mode and number of proofs:**
|    ``directory_exists(+atom)`` - ``zero_or_one``


.. raw:: html

   <div id="file_exists/1"> </div>

.. index:: file_exists/1
.. _osp/0::file_exists/1:

``file_exists/1``
^^^^^^^^^^^^^^^^^

True if the specified file exists and is a regular file (irrespective of file permissions).

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``file_exists(File)``
| **Mode and number of proofs:**
|    ``file_exists(+atom)`` - ``zero_or_one``


.. raw:: html

   <div id="file_modification_time/2"> </div>

.. index:: file_modification_time/2
.. _osp/0::file_modification_time/2:

``file_modification_time/2``
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

File modification time (which can be used for comparison).

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``file_modification_time(File,Time)``
| **Mode and number of proofs:**
|    ``file_modification_time(+atom,-integer)`` - ``zero_or_one``


.. raw:: html

   <div id="file_size/2"> </div>

.. index:: file_size/2
.. _osp/0::file_size/2:

``file_size/2``
^^^^^^^^^^^^^^^

File size (in bytes).

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``file_size(File,Size)``
| **Mode and number of proofs:**
|    ``file_size(+atom,-integer)`` - ``zero_or_one``


.. raw:: html

   <div id="file_permission/2"> </div>

.. index:: file_permission/2
.. _osp/0::file_permission/2:

``file_permission/2``
^^^^^^^^^^^^^^^^^^^^^

True if the specified file has the specified permission (read, write, or execute).

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``file_permission(File,Permission)``
| **Mode and number of proofs:**
|    ``file_permission(+atom,?atom)`` - ``zero_or_one``


.. raw:: html

   <div id="rename_file/2"> </div>

.. index:: rename_file/2
.. _osp/0::rename_file/2:

``rename_file/2``
^^^^^^^^^^^^^^^^^

Renames a file or a directory.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``rename_file(Old,New)``
| **Mode and number of proofs:**
|    ``rename_file(+atom,+atom)`` - ``zero_or_one``


.. raw:: html

   <div id="delete_file/1"> </div>

.. index:: delete_file/1
.. _osp/0::delete_file/1:

``delete_file/1``
^^^^^^^^^^^^^^^^^

Deletes a file.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``delete_file(File)``
| **Mode and number of proofs:**
|    ``delete_file(+atom)`` - ``one``


.. raw:: html

   <div id="environment_variable/2"> </div>

.. index:: environment_variable/2
.. _osp/0::environment_variable/2:

``environment_variable/2``
^^^^^^^^^^^^^^^^^^^^^^^^^^

Returns an environment variable value. Fails if the variable does not exists.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``environment_variable(Variable,Value)``
| **Mode and number of proofs:**
|    ``environment_variable(+atom,?atom)`` - ``zero_or_one``


.. raw:: html

   <div id="time_stamp/1"> </div>

.. index:: time_stamp/1
.. _osp/0::time_stamp/1:

``time_stamp/1``
^^^^^^^^^^^^^^^^

Returns a system-dependent time stamp, which can be used for sorting, but should be regarded otherwise as an opaque term.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``time_stamp(Time)``
| **Mode and number of proofs:**
|    ``time_stamp(-ground)`` - ``one``


.. raw:: html

   <div id="date_time/7"> </div>

.. index:: date_time/7
.. _osp/0::date_time/7:

``date_time/7``
^^^^^^^^^^^^^^^

Returns the current date and time.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``date_time(Year,Month,Day,Hours,Minutes,Seconds,Milliseconds)``
| **Mode and number of proofs:**
|    ``date_time(-integer,-integer,-integer,-integer,-integer,-integer,-integer)`` - ``one``


.. raw:: html

   <div id="cpu_time/1"> </div>

.. index:: cpu_time/1
.. _osp/0::cpu_time/1:

``cpu_time/1``
^^^^^^^^^^^^^^

System cpu time in seconds.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``cpu_time(Seconds)``
| **Mode and number of proofs:**
|    ``cpu_time(-number)`` - ``one``


.. raw:: html

   <div id="wall_time/1"> </div>

.. index:: wall_time/1
.. _osp/0::wall_time/1:

``wall_time/1``
^^^^^^^^^^^^^^^

Wall time in seconds.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``wall_time(Seconds)``
| **Mode and number of proofs:**
|    ``wall_time(-number)`` - ``one``


.. raw:: html

   <div id="operating_system_type/1"> </div>

.. index:: operating_system_type/1
.. _osp/0::operating_system_type/1:

``operating_system_type/1``
^^^^^^^^^^^^^^^^^^^^^^^^^^^

Operating system type. Possible values are "unix", "windows", and "unknown".

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``operating_system_type(Type)``
| **Mode and number of proofs:**
|    ``operating_system_type(?atom)`` - ``one``


.. raw:: html

   <div id="command_line_arguments/1"> </div>

.. index:: command_line_arguments/1
.. _osp/0::command_line_arguments/1:

``command_line_arguments/1``
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Returns a list with the command line arguments that occur after "--".

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``command_line_arguments(Arguments)``
| **Mode and number of proofs:**
|    ``command_line_arguments(-list(atom))`` - ``one``


.. raw:: html

   <div id="sleep/1"> </div>

.. index:: sleep/1
.. _osp/0::sleep/1:

``sleep/1``
^^^^^^^^^^^

Suspends execution the given number of seconds.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``sleep(Seconds)``
| **Mode and number of proofs:**
|    ``sleep(+number)`` - ``one``


Protected interface
-------------------

(none)

Private predicates
------------------

(none)

Operators
---------

(none)

Remarks
-------

(none)

.. seealso::

   :ref:`os <os/0>`, :ref:`os_types <os_types/0>`

