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• Python Basic Tutorial

1. Python Library Path Mac Os
2. Python Open File Path
3. Python Library Path Mac Os
4. Mac Change Python Path

• Python Advanced Tutorial

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Python is available on a wide variety of platforms including Linux and Mac OS X. Let's understand how to set up our Python environment.

Local Environment Setup

Open a terminal window and type 'python' to find out if it is already installed and which version is installed.

• Unix (Solaris, Linux, FreeBSD, AIX, HP/UX, SunOS, IRIX, etc.)
• Win 9x/NT/2000
• Macintosh (Intel, PPC, 68K)
• OS/2
• DOS (multiple versions)
• PalmOS
• Nokia mobile phones
• Windows CE
• Acorn/RISC OS
• BeOS
• Amiga
• VMS/OpenVMS
• QNX
• VxWorks
• Psion
• Python has also been ported to the Java and .NET virtual machines

Getting Python

The most up-to-date and current source code, binaries, documentation, news, etc., is available on the official website of Python https://www.python.org/

You can download Python documentation from https://www.python.org/doc/. The documentation is available in HTML, PDF, and PostScript formats.

Installing Python

Python distribution is available for a wide variety of platforms. You need to download only the binary code applicable for your platform and install Python.

If the binary code for your platform is not available, you need a C compiler to compile the source code manually. Compiling the source code offers more flexibility in terms of choice of features that you require in your installation.

Here is a quick overview of installing Python on various platforms −

Unix and Linux Installation

Here are the simple steps to install Python on Unix/Linux machine.

• Open a Web browser and go to https://www.python.org/downloads/.

• Follow the link to download zipped source code available for Unix/Linux.

• Download and extract files.

• Editing the Modules/Setup file if you want to customize some options.

• run ./configure script

• make

• make install

This installs Python at standard location /usr/local/bin and its libraries at /usr/local/lib/pythonXX where XX is the version of Python.

Windows Installation

Here are the steps to install Python on Windows machine.

• Open a Web browser and go to https://www.python.org/downloads/.

• Follow the link for the Windows installer python-XYZ.msi file where XYZ is the version you need to install.

• To use this installer python-XYZ.msi, the Windows system must support Microsoft Installer 2.0. Save the installer file to your local machine and then run it to find out if your machine supports MSI.

• Run the downloaded file. This brings up the Python install wizard, which is really easy to use. Just accept the default settings, wait until the install is finished, and you are done.

Macintosh Installation

Recent Macs come with Python installed, but it may be several years out of date. See http://www.python.org/download/mac/ for instructions on getting the current version along with extra tools to support development on the Mac. For older Mac OS's before Mac OS X 10.3 (released in 2003), MacPython is available.

Jack Jansen maintains it and you can have full access to the entire documentation at his website − http://www.cwi.nl/~jack/macpython.html. You can find complete installation details for Mac OS installation.

Setting up PATH

Programs and other executable files can be in many directories, so operating systems provide a search path that lists the directories that the OS searches for executables.

The path is stored in an environment variable, which is a named string maintained by the operating system. This variable contains information available to the command shell and other programs.

The path variable is named as PATH in Unix or Path in Windows (Unix is case sensitive; Windows is not).

In Mac OS, the installer handles the path details. To invoke the Python interpreter from any particular directory, you must add the Python directory to your path.

Setting path at Unix/Linux

To add the Python directory to the path for a particular session in Unix −

• In the csh shell − type setenv PATH '$PATH:/usr/local/bin/python' and press Enter.

• In the bash shell (Linux) − type export PATH='$PATH:/usr/local/bin/python' and press Enter.

• In the sh or ksh shell − type PATH='$PATH:/usr/local/bin/python' and press Enter.

• Note − /usr/local/bin/python is the path of the Python directory

Setting path at Windows

To add the Python directory to the path for a particular session in Windows −

At the command prompt − type path %path%;C:Python and press Enter.

Note − C:Python is the path of the Python directory

Python Environment Variables

Here are important environment variables, which can be recognized by Python −

Running Python

There are three different ways to start Python −

Interactive Interpreter

You can start Python from Unix, DOS, or any other system that provides you a command-line interpreter or shell window.

Enter python the command line.

Start coding right away in the interactive interpreter.

Here is the list of all the available command line options −

Script from the Command-line

A Python script can be executed at command line by invoking the interpreter on your application, as in the following −

Note − Be sure the file permission mode allows execution.

Integrated Development Environment

You can run Python from a Graphical User Interface (GUI) environment as well, if you have a GUI application on your system that supports Python.

• Unix − IDLE is the very first Unix IDE for Python.

• Windows − PythonWin is the first Windows interface for Python and is an IDE with a GUI.

• Macintosh − The Macintosh version of Python along with the IDLE IDE is available from the main website, downloadable as either MacBinary or BinHex'd files.

If you are not able to set up the environment properly, then you can take help from your system admin. Make sure the Python environment is properly set up and working perfectly fine.

Note − All the examples given in subsequent chapters are executed with Python 2.4.3 version available on CentOS flavor of Linux.

We already have set up Python Programming environment online, so that you can execute all the available examples online at the same time when you are learning theory. Feel free to modify any example and execute it online.

Source code:Lib/posixpath.py (for POSIX) andLib/ntpath.py (for Windows NT).

This module implements some useful functions on pathnames. To read orwrite files see open(), and for accessing the filesystem see theos module. The path parameters can be passed as either strings,or bytes. Applications are encouraged to represent file names as(Unicode) character strings. Unfortunately, some file names may not berepresentable as strings on Unix, so applications that need to supportarbitrary file names on Unix should use bytes objects to representpath names. Vice versa, using bytes objects cannot represent all filenames on Windows (in the standard mbcs encoding), hence Windowsapplications should use string objects to access all files.

Unlike a unix shell, Python does not do any automatic path expansions.Functions such as expanduser() and expandvars() can be invokedexplicitly when an application desires shell-like path expansion. (See alsothe glob module.)

See also

The pathlib module offers high-level path objects.

Note

All of these functions accept either only bytes or only string objects astheir parameters. The result is an object of the same type, if a path orfile name is returned.

Note

Since different operating systems have different path name conventions, thereare several versions of this module in the standard library. Theos.path module is always the path module suitable for the operatingsystem Python is running on, and therefore usable for local paths. However,you can also import and use the individual modules if you want to manipulatea path that is always in one of the different formats. They all have thesame interface:

• posixpath for UNIX-style paths

• ntpath for Windows paths

Changed in version 3.8: exists(), lexists(), isdir(), isfile(),islink(), and ismount() now return False instead ofraising an exception for paths that contain characters or bytesunrepresentable at the OS level.

Return a normalized absolutized version of the pathname path. On mostplatforms, this is equivalent to calling the function normpath() asfollows: normpath(join(os.getcwd(),path)).

Changed in version 3.6: Accepts a path-like object.

Return the base name of pathname path. This is the second element of thepair returned by passing path to the function split(). Note thatthe result of this function is differentfrom the Unix basename program; where basename for'/foo/bar/' returns 'bar', the basename() function returns anempty string (').

Changed in version 3.6: Accepts a path-like object.

Return the longest common sub-path of each pathname in the sequencepaths. Raise ValueError if paths contain both absoluteand relative pathnames, the paths are on the different drives orif paths is empty. Unlike commonprefix(), this returns avalid path.

Availability: Unix, Windows.

Changed in version 3.6: Accepts a sequence of path-like objects.

Return the longest path prefix (taken character-by-character) that is aprefix of all paths in list. If list is empty, return the empty string(').

Note

This function may return invalid paths because it works acharacter at a time. To obtain a valid path, seecommonpath().

Changed in version 3.6: Accepts a path-like object.

Return the directory name of pathname path. This is the first element ofthe pair returned by passing path to the function split().

Changed in version 3.6: Accepts a path-like object.

Return True if path refers to an existing path or an openfile descriptor. Returns False for broken symbolic links. Onsome platforms, this function may return False if permission isnot granted to execute os.stat() on the requested file, evenif the path physically exists.

Changed in version 3.3: path can now be an integer: True is returned if it is an open file descriptor, False otherwise.

Changed in version 3.6: Accepts a path-like object.

Return True if path refers to an existing path. Returns True forbroken symbolic links. Equivalent to exists() on platforms lackingos.lstat().

Changed in version 3.6: Accepts a path-like object.

Python Library Path Mac Os

On Unix and Windows, return the argument with an initial component of ~ or~user replaced by that user’s home directory.

On Unix, an initial ~ is replaced by the environment variable HOMEif it is set; otherwise the current user’s home directory is looked up in thepassword directory through the built-in module pwd. An initial ~useris looked up directly in the password directory.

On Windows, USERPROFILE will be used if set, otherwise a combinationof HOMEPATH and HOMEDRIVE will be used. An initial~user is handled by stripping the last directory component from the createduser path derived above.

If the expansion fails or if the path does not begin with a tilde, the path isreturned unchanged.

Changed in version 3.6: Accepts a path-like object.

Changed in version 3.8: No longer uses HOME on Windows.

Return the argument with environment variables expanded. Substrings of the form$name or ${name} are replaced by the value of environment variablename. Malformed variable names and references to non-existing variables areleft unchanged.

On Windows, %name% expansions are supported in addition to $name and${name}.

Changed in version 3.6: Accepts a path-like object.

Return the time of last access of path. The return value is a floating point number givingthe number of seconds since the epoch (see the time module). RaiseOSError if the file does not exist or is inaccessible.

Return the time of last modification of path. The return value is a floating point numbergiving the number of seconds since the epoch (see the time module).Raise OSError if the file does not exist or is inaccessible.

Changed in version 3.6: Accepts a path-like object.

Return the system’s ctime which, on some systems (like Unix) is the time of thelast metadata change, and, on others (like Windows), is the creation time for path.The return value is a number giving the number of seconds since the epoch (seethe time module). Raise OSError if the file does not exist oris inaccessible.

Changed in version 3.6: Accepts a path-like object.

Return the size, in bytes, of path. Raise OSError if the file doesnot exist or is inaccessible.

Changed in version 3.6: Accepts a path-like object.

Return True if path is an absolute pathname. On Unix, that means itbegins with a slash, on Windows that it begins with a (back)slash after choppingoff a potential drive letter.

Changed in version 3.6: Accepts a path-like object.

Python Open File Path

Return True if path is an existing regular file.This follows symbolic links, so both islink() and isfile() canbe true for the same path.

Changed in version 3.6: Accepts a path-like object.

Return True if path is an existing directory. Thisfollows symbolic links, so both islink() and isdir() can be truefor the same path.

Changed in version 3.6: Accepts a path-like object.

Return True if path refers to an existing directoryentry that is a symbolic link. Always False if symbolic links are notsupported by the Python runtime.

Changed in version 3.6: Accepts a path-like object.

Return True if pathname path is a mount point: a point in afile system where a different file system has been mounted. On POSIX, thefunction checks whether path’s parent, path/.., is on a differentdevice than path, or whether path/.. and path point to the samei-node on the same device — this should detect mount points for all Unixand POSIX variants. It is not able to reliably detect bind mounts on thesame filesystem. On Windows, a drive letter root and a share UNC arealways mount points, and for any other path GetVolumePathName is calledto see if it is different from the input path.

New in version 3.4: Support for detecting non-root mount points on Windows.

Changed in version 3.6: Accepts a path-like object.

Join one or more path components intelligently. The return value is theconcatenation of path and any members of *paths with exactly onedirectory separator (os.sep) following each non-empty part except thelast, meaning that the result will only end in a separator if the lastpart is empty. If a component is an absolute path, all previouscomponents are thrown away and joining continues from the absolute pathcomponent.

On Windows, the drive letter is not reset when an absolute path component(e.g., r'foo') is encountered. If a component contains a driveletter, all previous components are thrown away and the drive letter isreset. Note that since there is a current directory for each drive,os.path.join('c:','foo') represents a path relative to the currentdirectory on drive C: (c:foo), not c:foo.

Changed in version 3.6: Accepts a path-like object for path and paths.

Normalize the case of a pathname. On Windows, convert all characters in thepathname to lowercase, and also convert forward slashes to backward slashes.On other operating systems, return the path unchanged.

Changed in version 3.6: Accepts a path-like object.

Normalize a pathname by collapsing redundant separators and up-levelreferences so that A//B, A/B/, A/./B and A/foo/../B allbecome A/B. This string manipulation may change the meaning of a paththat contains symbolic links. On Windows, it converts forward slashes tobackward slashes. To normalize case, use normcase().

Changed in version 3.6: Accepts a path-like object.

Return the canonical path of the specified filename, eliminating any symboliclinks encountered in the path (if they are supported by the operatingsystem).

Note

When symbolic link cycles occur, the returned path will be one member ofthe cycle, but no guarantee is made about which member that will be.

Changed in version 3.6: Accepts a path-like object.

Changed in version 3.8: Symbolic links and junctions are now resolved on Windows.

Return a relative filepath to path either from the current directory orfrom an optional start directory. This is a path computation: thefilesystem is not accessed to confirm the existence or nature of path orstart.

start defaults to os.curdir.

Availability: Unix, Windows.

Changed in version 3.6: Accepts a path-like object.

Return True if both pathname arguments refer to the same file or directory.This is determined by the device number and i-node number and raises anexception if an os.stat() call on either pathname fails.

Availability: Unix, Windows.

Changed in version 3.4: Windows now uses the same implementation as all other platforms.

Changed in version 3.6: Accepts a path-like object.

Return True if the file descriptors fp1 and fp2 refer to the same file.

Availability: Unix, Windows.

Changed in version 3.6: Accepts a path-like object.

Return True if the stat tuples stat1 and stat2 refer to the same file.These structures may have been returned by os.fstat(),os.lstat(), or os.stat(). This function implements theunderlying comparison used by samefile() and sameopenfile().

Availability: Unix, Windows.

Changed in version 3.6: Accepts a path-like object.

Split the pathname path into a pair, (head,tail) where tail is thelast pathname component and head is everything leading up to that. Thetail part will never contain a slash; if path ends in a slash, tailwill be empty. If there is no slash in path, head will be empty. Ifpath is empty, both head and tail are empty. Trailing slashes arestripped from head unless it is the root (one or more slashes only). Inall cases, join(head,tail) returns a path to the same location as path(but the strings may differ). Also see the functions dirname() andbasename().

Changed in version 3.6: Accepts a path-like object.

Split the pathname path into a pair (drive,tail) where drive is eithera mount point or the empty string. On systems which do not use drivespecifications, drive will always be the empty string. In all cases, drive+tail will be the same as path.

On Windows, splits a pathname into drive/UNC sharepoint and relative path.

If the path contains a drive letter, drive will contain everythingup to and including the colon.e.g. splitdrive('c:/dir') returns ('c:','/dir')

If the path contains a UNC path, drive will contain the host nameand share, up to but not including the fourth separator.e.g. splitdrive('//host/computer/dir') returns ('//host/computer','/dir')

Changed in version 3.6: Accepts a path-like object.

Python Library Path Mac Os

Split the pathname path into a pair (root,ext) such that root+extpath, and ext is empty or begins with a period and contains at most oneperiod. Leading periods on the basename are ignored; splitext('.cshrc')returns ('.cshrc',').

Changed in version 3.6: Accepts a path-like object.

Mac Change Python Path

True if arbitrary Unicode strings can be used as file names (within limitationsimposed by the file system).