- Os X Command Line For Display A File Online
- Os X Command Line For Display A File Size
- Os X Command Line For Display A File Online
- Os X Command Line For Display A File Windows 10
The command line interface is an alternate method of interacting with macOS and Mac OS X, relying on text based command entry to execute commands and perform tasks. It is accessed on the Mac by using the Terminal application. Generally, the command line is considered advanced, and thus it’s usage tends to be more complex than many standard.
The CPython interpreter scans the command line and the environment for varioussettings.
CPython implementation detail: Other implementations’ command line schemes may differ. SeeAlternate Implementations for further resources.
1.1. Command line¶
When invoking Python, you may specify any of these options:
The most common use case is, of course, a simple invocation of a script:
1.1.1. Interface options¶
The interpreter interface resembles that of the UNIX shell, but provides someadditional methods of invocation:
- When called with standard input connected to a tty device, it prompts forcommands and executes them until an EOF (an end-of-file character, you canproduce that with Ctrl-D on UNIX or Ctrl-Z, Enter on Windows) is read.
- When called with a file name argument or with a file as standard input, itreads and executes a script from that file.
- When called with a directory name argument, it reads and executes anappropriately named script from that directory.
- When called with -ccommand, it executes the Python statement(s) given ascommand. Here command may contain multiple statements separated bynewlines. Leading whitespace is significant in Python statements!
- When called with -mmodule-name, the given module is located on thePython module path and executed as a script.
In non-interactive mode, the entire input is parsed before it is executed.
An interface option terminates the list of options consumed by the interpreter,all consecutive arguments will end up in sys.argv – note that the firstelement, subscript zero (sys.argv[0]), is a string reflecting the program’ssource.
Execute the Python code in command. command can be one or morestatements separated by newlines, with significant leading whitespace as innormal module code.
If this option is given, the first element of sys.argv will be'-c' and the current directory will be added to the start ofsys.path (allowing modules in that directory to be imported as toplevel modules).
Search sys.path for the named module and execute its contents asthe __main__ module.
Since the argument is a module name, you must not give a file extension(.py). The module-name should be a valid Python module name, butthe implementation may not always enforce this (e.g. it may allow you touse a name that includes a hyphen).
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Package names are also permitted. When a package name is supplied insteadof a normal module, the interpreter will execute <pkg>.__main__ asthe main module. This behaviour is deliberately similar to the handlingof directories and zipfiles that are passed to the interpreter as thescript argument. Bittorrent mac os x 10.4 11 download.
Note
This option cannot be used with built-in modules and extension moduleswritten in C, since they do not have Python module files. However, itcan still be used for precompiled modules, even if the original sourcefile is not available.
If this option is given, the first element of sys.argv will be thefull path to the module file (while the module file is being located, thefirst element will be set to '-m'). As with the -c option,the current directory will be added to the start of sys.path.
Many standard library modules contain code that is invoked on their executionas a script. An example is the timeit module:
See also
- runpy.run_module()
- Equivalent functionality directly available to Python code
PEP 338 – Executing modules as scripts
Changed in version 3.1: Supply the package name to run a __main__ submodule.
Read commands from standard input (sys.stdin). If standard input isa terminal, -i is implied.
If this option is given, the first element of sys.argv will be'-' and the current directory will be added to the start ofsys.path.
Execute the Python code contained in script, which must be a filesystempath (absolute or relative) referring to either a Python file, a directorycontaining a __main__.py file, or a zipfile containing a__main__.py file.
If this option is given, the first element of sys.argv will be thescript name as given on the command line.
If the script name refers directly to a Python file, the directorycontaining that file is added to the start of sys.path, and thefile is executed as the __main__ module.
If the script name refers to a directory or zipfile, the script name isadded to the start of sys.path and the __main__.py file inthat location is executed as the __main__ module.
If no interface option is given, -i is implied, sys.argv[0] isan empty string (') and the current directory will be added to thestart of sys.path.
1.1.2. Generic options¶
Print a short description of all command line options.
Print the Python version number and exit. Example output could be:
1.1.3. Miscellaneous options¶
Issue a warning when comparing str and bytes. Issue an error when theoption is given twice (-bb).
If given, Python won’t try to write .pyc or .pyo files on theimport of source modules. See also PYTHONDONTWRITEBYTECODE.
Turn on parser debugging output (for wizards only, depending on compilationoptions). See also PYTHONDEBUG.
Ignore all PYTHON* environment variables, e.g.PYTHONPATH and PYTHONHOME, that might be set.
When a script is passed as first argument or the -c option is used,enter interactive mode after executing the script or the command, even whensys.stdin does not appear to be a terminal. ThePYTHONSTARTUP file is not read.
This can be useful to inspect global variables or a stack trace when a scriptraises an exception. See also PYTHONINSPECT.
Turn on basic optimizations. This changes the filename extension forcompiled (bytecode) files from .pyc to .pyo. See alsoPYTHONOPTIMIZE.
Discard docstrings in addition to the -O optimizations.
Don’t display the copyright and version messages even in interactive mode.
Kept for compatibility. On Python 3.3 and greater, hash randomization isturned on by default.
On previous versions of Python, this option turns on hash randomization,so that the __hash__() values of str, bytes and datetimeare “salted” with an unpredictable random value. Although they remainconstant within an individual Python process, they are not predictablebetween repeated invocations of Python.
Hash randomization is intended to provide protection against adenial-of-service caused by carefully-chosen inputs that exploit the worstcase performance of a dict construction, O(n^2) complexity. Seehttp://www.ocert.org/advisories/ocert-2011-003.html for details.
PYTHONHASHSEED allows you to set a fixed value for the hashseed secret.
New in version 3.2.3.
Don’t add the usersite-packagesdirectory tosys.path.
See also
PEP 370 – Per user site-packages directory
Disable the import of the module site and the site-dependentmanipulations of sys.path that it entails. Also disable thesemanipulations if site is explicitly imported later (callsite.main() if you want them to be triggered).
Force the binary layer of the stdout and stderr streams (which isavailable as their buffer attribute) to be unbuffered. The text I/Olayer will still be line-buffered if writing to the console, orblock-buffered if redirected to a non-interactive file.
See also PYTHONUNBUFFERED.
Print a message each time a module is initialized, showing the place(filename or built-in module) from which it is loaded. When given twice(-vv), print a message for each file that is checked for whensearching for a module. Also provides information on module cleanup at exit.See also PYTHONVERBOSE.
Warning control. Python’s warning machinery by default prints warningmessages to sys.stderr. A typical warning message has the followingform:
By default, each warning is printed once for each source line where itoccurs. This option controls how often warnings are printed.
Multiple -W options may be given; when a warning matches more thanone option, the action for the last matching option is performed. Invalid-W options are ignored (though, a warning message is printed aboutinvalid options when the first warning is issued).
Warnings can also be controlled from within a Python program using thewarnings module.
The simplest form of argument is one of the following action strings (or aunique abbreviation):
- ignore
- Ignore all warnings.
- default
- Explicitly request the default behavior (printing each warning once persource line).
- all
- Print a warning each time it occurs (this may generate many messages if awarning is triggered repeatedly for the same source line, such as inside aloop).
- module
- Print each warning only the first time it occurs in each module.
- once
- Print each warning only the first time it occurs in the program.
- error
- Raise an exception instead of printing a warning message.
The full form of argument is:
Here, action is as explained above but only applies to messages that matchthe remaining fields. Empty fields match all values; trailing empty fieldsmay be omitted. The message field matches the start of the warning messageprinted; this match is case-insensitive. The category field matches thewarning category. This must be a class name; the match tests whether theactual warning category of the message is a subclass of the specified warningcategory. The full class name must be given. The module field matches the(fully-qualified) module name; this match is case-sensitive. The linefield matches the line number, where zero matches all line numbers and isthus equivalent to an omitted line number.
See also
warnings – the warnings module
PEP 230 – Warning framework
PYTHONWARNINGS
Skip the first line of the source, allowing use of non-Unix forms of#!cmd. This is intended for a DOS specific hack only.
Note
The line numbers in error messages will be off by one.
Reserved for various implementation-specific options. CPython currentlydefines just one, you can use -Xfaulthandler to enablefaulthandler. It also allows to pass arbitrary values and retrievethem through the sys._xoptions dictionary.
Changed in version 3.2: It is now allowed to pass -X with CPython.
1.1.4. Options you shouldn’t use¶
Reserved for use by Jython.
1.2. Environment variables¶
These environment variables influence Python’s behavior, they are processedbefore the command-line switches other than -E. It is customary thatcommand-line switches override environmental variables where there is aconflict.
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Change the location of the standard Python libraries. By default, thelibraries are searched in prefix/lib/pythonversion andexec_prefix/lib/pythonversion, where prefix andexec_prefix are installation-dependent directories, both defaultingto /usr/local.
When PYTHONHOME is set to a single directory, its value replacesboth prefix and exec_prefix. To specify different valuesfor these, set PYTHONHOME to prefix:exec_prefix.
Augment the default search path for module files. The format is the same asthe shell’s PATH: one or more directory pathnames separated byos.pathsep (e.g. colons on Unix or semicolons on Windows).Non-existent directories are silently ignored.
In addition to normal directories, individual PYTHONPATH entriesmay refer to zipfiles containing pure Python modules (in either source orcompiled form). Extension modules cannot be imported from zipfiles.
The default search path is installation dependent, but generally begins withprefix/lib/pythonversion (see PYTHONHOME above). Itis always appended to PYTHONPATH.
An additional directory will be inserted in the search path in front ofPYTHONPATH as described above underInterface options. The search path can be manipulated fromwithin a Python program as the variable sys.path.
If this is the name of a readable file, the Python commands in that file areexecuted before the first prompt is displayed in interactive mode. The fileis executed in the same namespace where interactive commands are executed sothat objects defined or imported in it can be used without qualification inthe interactive session. You can also change the prompts sys.ps1 andsys.ps2 in this file.
Set this to a non-empty string to cause the time module to requiredates specified as strings to include 4-digit years, otherwise 2-digit yearsare converted based on rules described in the time moduledocumentation.
If this is set to a non-empty string it is equivalent to specifying the-O option. If set to an integer, it is equivalent to specifying-O multiple times.
If this is set to a non-empty string it is equivalent to specifying the-d option. If set to an integer, it is equivalent to specifying-d multiple times.
If this is set to a non-empty string it is equivalent to specifying the-i option.
This variable can also be modified by Python code using os.environto force inspect mode on program termination.
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If this is set to a non-empty string it is equivalent to specifying the-u option.
If this is set to a non-empty string it is equivalent to specifying the-v option. How to install os x 10.8 mountain lion for free windows 7. If set to an integer, it is equivalent to specifying-v multiple times.
If this is set, Python ignores case in import statements. Thisonly works on Windows and OS X.
If this is set, Python won’t try to write .pyc or .pyo files on theimport of source modules. This is equivalent to specifying the -Boption.
If this variable is not set or set to random, a random value is usedto seed the hashes of str, bytes and datetime objects.
If PYTHONHASHSEED is set to an integer value, it is used as a fixedseed for generating the hash() of the types covered by the hashrandomization.
Its purpose is to allow repeatable hashing, such as for selftests for theinterpreter itself, or to allow a cluster of python processes to share hashvalues.
The integer must be a decimal number in the range [0,4294967295]. Specifyingthe value 0 will disable hash randomization.
If this is set before running the interpreter, it overrides the encoding usedfor stdin/stdout/stderr, in the syntax encodingname:errorhandler. The:errorhandler part is optional and has the same meaning as instr.encode().
For stderr, the :errorhandler part is ignored; the handler will always be'backslashreplace'.
If this is set, Python won’t add the usersite-packagesdirectory to sys.path.
See also
PEP 370 – Per user site-packages directory
Defines the userbasedirectory, which is used tocompute the path of the usersite-packagesdirectoryand Distutils installation paths forpythonsetup.pyinstall--user.
See also
PEP 370 – Per user site-packages directory
If this environment variable is set, sys.argv[0] will be set to itsvalue instead of the value got through the C runtime. Only works onMac OS X.
This is equivalent to the -W option. If set to a commaseparated string, it is equivalent to specifying -W multipletimes.
If this environment variable is set, faulthandler.enable() is calledat startup: install a handler for SIGSEGV, SIGFPE,SIGABRT, SIGBUS and SIGILL signals to dump thePython traceback. This is equivalent to -Xfaulthandleroption.
1.2.1. Debug-mode variables¶
Setting these variables only has an effect in a debug build of Python, that is,if Python was configured with the --with-pydebug build option.
If set, Python will print threading debug info.
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If set, Python will dump objects and reference counts still alive aftershutting down the interpreter.
If set, Python will print memory allocation statistics every time a newobject arena is created, and on shutdown.
Manipulating files and viewing folder content is fun, but the command line in OS X Yosemite is capable of so much more! Focus your attention on some of the other useful tasks that you can perform with the command line.
OS X comes stocked with a full set of useful commands. You can discover many of the commands that are installed by viewing the files in /usr/bin. Type cd /usr/bin to navigate there. Other locations to peruse include /bin and /usr/local/bin.
Calendar command
A favorite command line functions is the cal command, which displays a calendar in text form. Simply entering cal at the prompt displays a calendar for the current month.
Append a number to the cal command to display a 12-month calendar for a specific year. For example, to view a calendar for 1970, type cal 1970.
Append a month number and a year number to display the calendar for that month. For example, to view a calendar for April 2014, type cal 04 2014.
Another useful command that’s related to the cal command is date. Type date at the command line to display the day, date, time, and year based on your computer’s settings.
Processes in OS X
Have you ever been curious about why your hard drive seems to spin and grind on occasion while your system is seemingly inactive? OS X sometimes has lots of stuff going on behind the scenes.
To discover what your computer is busy doing at any time, use the top command to display all the actions that your computer is currently performing. These activities are processes; some are created when you launch applications, and others are simply tasks that OS X has to take care of to keep things running smoothly.
Besides listing the names of the various processes currently in use, top tells you how much of your CPU is being devoted to each process. This lets you know what process is currently hogging all your computing power.
Sometimes a process stalls, effectively freezing that action. By using the top command to find the Process ID (PID) of the offending process, you can halt the process. Simply use the kill command followed by the PID of the process you want to stop. (The man help page for the kill command gives more options that may help terminate stubborn processes with prejudice.)
Do not take a cavalier attitude when killing processes! Although OS X is extremely stable, removing the wrong process — such as init or machinit — is rather like removing a leg from one of those deep-sea drilling platforms: the very definition of Not Good. You could lock up your system and lose whatever you’re doing in other applications.
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If you simply want to shut down a misbehaving program, go graphical again (at least for a moment) and use the Force Quit menu command from the Apple menu.
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Like top, another handy command for examining process info is ps (short for process status). Most often, you’ll want to append a few flags to the ps command to get the information that you desire. For example, try the following command, which displays additional information for each process:
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The man page for ps explains what each flag means.