Python 实用宝典

Question 1

Could you explain to me what the difference is between calling

python -m mymod1 mymod2.py args

and

python mymod1.py mymod2.py args

It seems in both cases mymod1.py is called and sys.argv is

['mymod1.py', 'mymod2.py', 'args']

So what is the -m switch for?

Question 2

The first line of the Rationale section of PEP 338 says:

Python 2.4 adds the command line switch -m to allow modules to be located using the Python module namespace for execution as scripts. The motivating examples were standard library modules such as pdb and profile, and the Python 2.4 implementation is fine for this limited purpose.

So you can specify any module in Python’s search path this way, not just files in the current directory. You’re correct that python mymod1.py mymod2.py args has exactly the same effect. The first line of the Scope of this proposal section states:

In Python 2.4, a module located using -m is executed just as if its filename had been provided on the command line.

With -m more is possible, like working with modules which are part of a package, etc. That’s what the rest of PEP 338 is about. Read it for more info.

Question 3

It’s worth mentioning this only works if the package has a file __main__.py Otherwise, this package can not be executed directly.

python -m some_package some_arguments

The python interpreter will looking for a __main__.py file in the package path to execute. It’s equivalent to:

python path_to_package/__main__.py somearguments

It will execute the content after:

if __name__ == "__main__":

Question 4

Despite this question having been asked and answered several times (e.g., here, here, here, and here) in my opinion no existing answer fully or concisely captures all the implications of the -m flag. Therefore, the following will attempt to improve on what has come before.

Introduction (TLDR)

The -m flag does a lot of things, not all of which will be needed all the time. In short it can be used to: (1) execute python code from the command line via modulename rather than filename (2) add a directory to sys.path for use in import resolution and (3) execute python code that contains relative imports from the command line.

Preliminaries

To explain the -m flag we first need to explain a little terminology.

Python’s primary organizational unit is known as a module. Module’s come in one of two flavors: code modules and package modules. A code module is any file that contains python executable code. A package module is a directory that contains other modules (either code modules or package modules). The most common type of code modules are *.py files while the most common type of package modules are directories containing an __init__.py file.

Python allows modules to be uniquely identified in two distinct ways: modulename and filename. In general, modules are identified by modulename in Python code (e.g., import <modulename>) and by filename on the command line (e.g., python <filename>). All python interpreters are able to convert modulenames to filenames by following the same few, well-defined rules. These rules hinge on the sys.path variable. By altering this variable one can change how Python resolves modulenames into filenames (for more on how this is done see PEP 302).

All modules (both code and package) can be executed (i.e., code associated with the module will be evaluated by the Python interpreter). Depending on the execution method (and module type) what code gets evaluated, and when, can change quite a bit. For example, if one executes a package module via python <filename> then <filename>/__init__.py will be evaluated followed by <filename>/__main__.py. On the other hand, if one executes that same package module via import <modulename> then only the package’s __init__.py will be executed.

Historical Development of `-m`

The -m flag was first introduced in Python 2.4.1. Initially its only purpose was to provide an alternative means of identifying the python module to execute from the command line. That is, if we knew both the <filename> and <modulename> for a module then the following two commands were equivalent: python <filename> <args> and python -m <modulename> <args>. One constraint with this iteration, according to PEP 338, was that -m only worked with top level modulenames (i.e., modules that could be found directly on sys.path without any intervening package modules).

With the completion of PEP 338 the -m feature was extended to support <modulename> representations beyond the top level. This meant names such as http.server were now fully supported. This extension also meant that each parent package in modulename was now evaluated (i.e., all parent package __init__.py files were evaluated) in addition to the module referenced by the modulename itself.

The final major feature enhancement for -m came with PEP 366. With this upgrade -m gained the ability to support not only absolute imports but also explicit relative imports when executing modules. This was achieved by changing -m so that it set the __package__ variable to the parent module of the given modulename (in addition to everything else it already did).

Use Cases

There are two notable use cases for the -m flag:

To execute modules from the command line for which one may not know their filename. This use case takes advantage of the fact that the Python interpreter knows how to convert modulenames to filenames. This is particularly advantageous when one wants to run stdlib modules or 3rd-party module from the command line. For example, very few people know the filename for the http.server module but most people do know its modulename so we can execute it from the command line using python -m http.server.
To execute a local package containing absolute or relative imports without needing to install it. This use case is detailed in PEP 338 and leverages the fact that the current working directory is added to sys.path rather than the module’s directory. This use case is very similar to using pip install -e . to install a package in develop/edit mode.

Shortcomings

With all the enhancements made to -m over the years it still has one major shortcoming — it can only execute modules written in Python (i.e., *.py). For example, if -m is used to execute a C compiled code module the following error will be produced, No code object available for <modulename> (see here for more details).

Detailed Comparisons

Effects of module execution via import statement (i.e., import <modulename>):

sys.path is not modified in any way
__name__ is set to the absolute form of <modulename>
__package__ is set to the immediate parent package in <modulename>
__init__.py is evaluated for all packages (including its own for package modules)
__main__.py is not evaluated for package modules; the code is evaluated for code modules

Effects of module execution via command line (i.e., python <filename>):

sys.path is modified to include the final directory in <filename>
__name__ is set to '__main__'
__package__ is set to None
__init__.py is not evaluated for any package (including its own for package modules)
__main__.py is evaluated for package modules; the code is evaluated for code modules.

Effects of module execution via command line with the -m flag (i.e., python -m <modulename>):

sys.path is modified to include the current directory
__name__ is set to '__main__'
__package__ is set to the immediate parent package in <modulename>
__init__.py is evaluated for all packages (including its own for package modules)
__main__.py is evaluated for package modules; the code is evaluated for code modules

Conclusion

The -m flag is, at its simplest, a means to execute python scripts from the command line by using modulenames rather than filenames. The real power of -m, however, is in its ability to combine the power of import statements (e.g., support for explicit relative imports and automatic package __init__ evaluation) with the convenience of the command line.

Question 5

Despite a ton of Googling, I can’t find any docs for pip’s command line options/arguments. What does pip install -U mean? Does anyone have a link to a list of pip’s options and arguments?

Question 6

Type pip install -h to list help:

-U, –upgrade Upgrade all packages to the newest available version

So, if you already have a package installed, it will upgrade the package for you. Without the -U switch it’ll tell you the package is already installed and exit.

Each pip subcommand has its own help listing. pip -h shows you overall help, and pip [subcommand] -h gives you help for that sub command, such as install.

You can also find the full reference documentation online; the General Options section covers switches available for every pip subcommand, while each subcommand has a separate Options section to cover subcommand-specific switches; see the pip install options section, for example.

Question 7

When I use subcommands with python argparse, I can get the selected arguments.

parser = argparse.ArgumentParser()
parser.add_argument('-g', '--global')
subparsers = parser.add_subparsers()   
foo_parser = subparsers.add_parser('foo')
foo_parser.add_argument('-c', '--count')
bar_parser = subparsers.add_parser('bar')
args = parser.parse_args(['-g, 'xyz', 'foo', '--count', '42'])
# args => Namespace(global='xyz', count='42')

So args doesn’t contain 'foo'. Simply writing sys.argv[1] doesn’t work because of the possible global args. How can I get the subcommand itself?

Question 8

The very bottom of the Python docs on argparse sub-commands explains how to do this:

>>> parser = argparse.ArgumentParser()
>>> parser.add_argument('-g', '--global')
>>> subparsers = parser.add_subparsers(dest="subparser_name") # this line changed
>>> foo_parser = subparsers.add_parser('foo')
>>> foo_parser.add_argument('-c', '--count')
>>> bar_parser = subparsers.add_parser('bar')
>>> args = parser.parse_args(['-g', 'xyz', 'foo', '--count', '42'])
>>> args
Namespace(count='42', global='xyz', subparser_name='foo')

You can also use the set_defaults() method referenced just above the example I found.

Question 9

ArgumentParser.add_subparsers has dest formal argument described as:

dest – name of the attribute under which sub-command name will be stored; by default None and no value is stored

In the example below of a simple task function layout using subparsers, the selected subparser is in parser.parse_args().subparser.

import argparse


def task_a(alpha):
    print('task a', alpha)


def task_b(beta, gamma):
    print('task b', beta, gamma)


if __name__ == '__main__':
    parser = argparse.ArgumentParser()
    subparsers = parser.add_subparsers(dest='subparser')

    parser_a = subparsers.add_parser('task_a')
    parser_a.add_argument(
        '-a', '--alpha', dest='alpha', help='Alpha description')

    parser_b = subparsers.add_parser('task_b')
    parser_b.add_argument(
        '-b', '--beta', dest='beta', help='Beta description')
    parser_b.add_argument(
        '-g', '--gamma', dest='gamma', default=42, help='Gamma description')

    kwargs = vars(parser.parse_args())
    globals()[kwargs.pop('subparser')](**kwargs)

Question 10

I’m scripting the checkout, build, distribution, test, and commit cycle for a large C++ solution that is using Monotone, CMake, Visual Studio Express 2008, and custom tests.

All of the other parts seem pretty straight-forward, but I don’t see how to compile the Visual Studio solution without getting the GUI.

The script is written in Python, but an answer that would allow me to just make a call to: os.system would do.

Question 11

I know of two ways to do it.

Method 1
The first method (which I prefer) is to use msbuild:

msbuild project.sln /Flags...

Method 2
You can also run:

vcexpress project.sln /build /Flags...

The vcexpress option returns immediately and does not print any output. I suppose that might be what you want for a script.

Note that DevEnv is not distributed with Visual Studio Express 2008 (I spent a lot of time trying to figure that out when I first had a similar issue).

So, the end result might be:

os.system("msbuild project.sln /p:Configuration=Debug")

You’ll also want to make sure your environment variables are correct, as msbuild and vcexpress are not by default on the system path. Either start the Visual Studio build environment and run your script from there, or modify the paths in Python (with os.putenv).

Question 12

MSBuild usually works, but I’ve run into difficulties before. You may have better luck with

devenv YourSolution.sln /Build

Question 13

To be honest I have to add my 2 cents.

You can do it with msbuild.exe. There are many version of the msbuild.exe.

C:\Windows\Microsoft.NET\Framework64\v2.0.50727\msbuild.exe C:\Windows\Microsoft.NET\Framework64\v3.5\msbuild.exe C:\Windows\Microsoft.NET\Framework64\v4.0.30319\msbuild.exe
C:\Windows\Microsoft.NET\Framework\v2.0.50727\msbuild.exe C:\Windows\Microsoft.NET\Framework\v3.5\msbuild.exe C:\Windows\Microsoft.NET\Framework\v4.0.30319\msbuild.exe

Use version you need. Basically you have to use the last one.

C:\Windows\Microsoft.NET\Framework64\v4.0.30319\msbuild.exe

So how to do it.

Run the COMMAND window
Input the path to msbuild.exe

C:\Windows\Microsoft.NET\Framework64\v4.0.30319\msbuild.exe

Input the path to the project solution like

“C:\Users\Clark.Kent\Documents\visual studio 2012\Projects\WpfApplication1\WpfApplication1.sln”

Add any flags you need after the solution path.
Press ENTER

Note you can get help about all possible flags like

C:\Windows\Microsoft.NET\Framework64\v4.0.30319\msbuild.exe /help

Question 14

Using msbuild as pointed out by others worked for me but I needed to do a bit more than just that. First of all, msbuild needs to have access to the compiler. This can be done by running:

"C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\vcvarsall.bat"

Then msbuild was not in my $PATH so I had to run it via its explicit path:

"C:\Windows\Microsoft.NET\Framework64\v4.0.30319\MSBuild.exe" myproj.sln

Lastly, my project was making use of some variables like $(VisualStudioDir). It seems those do not get set by msbuild so I had to set them manually via the /property option:

"C:\Windows\Microsoft.NET\Framework64\v4.0.30319\MSBuild.exe" /property:VisualStudioDir="C:\Users\Administrator\Documents\Visual Studio 2013" myproj.sln

That line then finally allowed me to compile my project.

Bonus: it seems that the command line tools do not require a registration after 30 days of using them like the “free” GUI-based Visual Studio Community edition does. With the Microsoft registration requirement in place, that version is hardly free. Free-as-in-facebook if anything…

Question 15

MSBuild is your friend.

msbuild "C:\path to solution\project.sln"

Question 16

DEVENV works well in many cases, but on a WIXPROJ to build my WIX installer, all I got is “CATASTROPHIC” error in the Out log.

This works: MSBUILD /Path/PROJECT.WIXPROJ /t:Build /p:Configuration=Release

Question 17

How do I run a python script from within the IDLE interactive shell?

The following throws an error:

>>> python helloworld.py
SyntaxError: invalid syntax

Question 18

Python3:

exec(open('helloworld.py').read())

If your file not in the same dir:

exec(open('./app/filename.py').read())

See https://stackoverflow.com/a/437857/739577 for passing global/local variables.

In deprecated Python versions

Python2 Built-in function: execfile

execfile('helloworld.py')

It normally cannot be called with arguments. But here’s a workaround:

import sys
sys.argv = ['helloworld.py', 'arg']  # argv[0] should still be the script name
execfile('helloworld.py')

Deprecated since 2.6: popen

import os
os.popen('python helloworld.py') # Just run the program
os.popen('python helloworld.py').read() # Also gets you the stdout

With arguments:

os.popen('python helloworld.py arg').read()

Advance usage: subprocess

import subprocess
subprocess.call(['python', 'helloworld.py']) # Just run the program
subprocess.check_output(['python', 'helloworld.py']) # Also gets you the stdout

With arguments:

subprocess.call(['python', 'helloworld.py', 'arg'])

Read the docs for details :-)

Tested with this basic helloworld.py:

import sys
if len(sys.argv) > 1:
    print(sys.argv[1])

Question 19

You can use this in python3:

exec(open(filename).read())

Question 20

The IDLE shell window is not the same as a terminal shell (e.g. running sh or bash). Rather, it is just like being in the Python interactive interpreter (python -i). The easiest way to run a script in IDLE is to use the Open command from the File menu (this may vary a bit depending on which platform you are running) to load your script file into an IDLE editor window and then use the Run -> Run Module command (shortcut F5).

Question 21

Try this

import os
import subprocess

DIR = os.path.join('C:\\', 'Users', 'Sergey', 'Desktop', 'helloword.py')

subprocess.call(['python', DIR])

Question 22

execFile('helloworld.py') does the job for me. A thing to note is to enter the complete directory name of the .py file if it isnt in the Python folder itself (atleast this is the case on Windows)

For example, execFile('C:/helloworld.py')

Question 23

EASIEST WAY

python -i helloworld.py  #Python 2

python3 -i helloworld.py #Python 3

Question 24

For example:

import subprocess

subprocess.call("C:\helloworld.py")

subprocess.call(["python", "-h"])

Question 25

In Python 3, there is no execFile. One can use exec built-in function, for instance:

import helloworld
exec('helloworld')

Question 26

In IDLE, the following works :-

import helloworld

I don’t know much about why it works, but it does..

Question 27

To run a python script in a python shell such as Idle or in a Django shell you can do the following using the exec() function. Exec() executes a code object argument. A code object in Python is simply compiled Python code. So you must first compile your script file and then execute it using exec(). From your shell:

>>>file_to_compile = open('/path/to/your/file.py').read()
>>>code_object = compile(file_to_compile, '<string>', 'exec')
>>>exec(code_object)

I’m using Python 3.4. See the compile and exec docs for detailed info.

Question 28

I tested this and it kinda works out :

exec(open('filename').read())  # Don't forget to put the filename between ' '

Question 29

you can do it by two ways

import file_name
exec(open('file_name').read())

but make sure that file should be stored where your program is running

Question 30

On Windows environment, you can execute py file on Python3 shell command line with the following syntax:

exec(open(‘absolute path to file_name’).read())

Below explains how to execute a simple helloworld.py file from python shell command line

File Location: C:/Users/testuser/testfolder/helloworld.py

File Content: print(“hello world”)

We can execute this file on Python3.7 Shell as below:

>>> import os
>>> abs_path = 'C://Users/testuser/testfolder'
>>> os.chdir(abs_path)
>>> os.getcwd()
'C:\\Users\\testuser\\testfolder'

>>> exec(open("helloworld.py").read())
hello world

>>> exec(open("C:\\Users\\testuser\\testfolder\\helloworld.py").read())
hello world

>>> os.path.abspath("helloworld.py")
'C:\\Users\\testuser\\testfolder\\helloworld.py'
>>> import helloworld
hello world

Question 31

There is one more alternative (for windows) –

    import os
    os.system('py "<path of program with extension>"')

Question 32

In a python console, one can try the following 2 ways.

under the same work directory,

1. >> import helloworld

# if you have a variable x, you can print it in the IDLE.

>> helloworld.x

# if you have a function func, you can also call it like this.

>> helloworld.func()

2. >> runfile(“./helloworld.py”)

Question 33

Can someone suggest how I can beautify JSON in Python or through the command line?

The only online based JSON beautifier which could do it was: http://jsonviewer.stack.hu/.

I need to use it from within Python, however.

This is my dataset:

{ "head": {"vars": [ "address" , "description" ,"listprice" ]} , "results": { "bindings": [ 
    {
        "address" : { "type":"string", "value" : " Dyne Road, London NW6"},
            "description" :{ "type":"string", "value" : "6 bed semi detached house"},
            "listprice" : { "type":"string", "value" : "1,150,000"}
    }
    ,
        {
            "address" : { "type":"string", "value" : " Tweedy Road, Bromley BR1"},
            "description" :{ "type":"string", "value" : "5 bed terraced house"},
            "listprice" : { "type":"string", "value" : "550,000"}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Vera Avenue, London N21"},
            "description" :{ "type":"string", "value" : "4 bed detached house"},
            "listprice" : { "type":"string", "value" : "

                995,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Wimbledon Park Side, London SW19"},
            "description" :{ "type":"string", "value" : "3 bedroom  property for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Westbere Road, West Hampstead, London NW2"},
            "description" :{ "type":"string", "value" : "5 bedroom  semi detached house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " The Avenue, Hatch End, Pinner HA5"},
            "description" :{ "type":"string", "value" : "5 bedroom  detached house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Princes Park Avenue, London NW11"},
            "description" :{ "type":"string", "value" : "4 bedroom  detached house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Canons Drive, Edgware HA8"},
            "description" :{ "type":"string", "value" : "4 bedroom  detached house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Westbere Road, West Hampstead NW2"},
            "description" :{ "type":"string", "value" : "5 bedroom  property for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Haymills Estate, Ealing, London"},
            "description" :{ "type":"string", "value" : "5 bedroom  property for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Dene Terrace Woodclyffe Drive, Chislehurst, Kent BR7"},
            "description" :{ "type":"string", "value" : "5 bedroom  terraced house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Dene Terrace Woodclyffe Drive, Chislehurst, Kent BR7"},
            "description" :{ "type":"string", "value" : "5 bedroom  semi detached house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Northwick Close, St John's Wood NW8"},
            "description" :{ "type":"string", "value" : "3 bedroom  property for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Claremont Gardens, Surbiton KT6"},
            "description" :{ "type":"string", "value" : "13 bedroom  property for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Dene Terrace Woodclyffe Drive, Chislehurst, Kent BR7"},
            "description" :{ "type":"string", "value" : "5 bedroom  end terrace house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Stamford Road, London N1"},
            "description" :{ "type":"string", "value" : "4 bedroom  terraced house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Stanhope Avenue, London N3"},
            "description" :{ "type":"string", "value" : "6 bedroom  property for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Haymills Estate, Ealing, London"},
            "description" :{ "type":"string", "value" : "5 bedroom  property for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Elms Crescent, London SW4"},
            "description" :{ "type":"string", "value" : "5 bedroom  property for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Princes Park Avenue, London NW11"},
            "description" :{ "type":"string", "value" : "4 bedroom  property for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Abbeville Road, London SW4"},
            "description" :{ "type":"string", "value" : "4 bedroom  property for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Canons Drive, Edgware HA8"},
            "description" :{ "type":"string", "value" : "4 bedroom  detached house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Henson Avenue, Willesdon Green NW2"},
            "description" :{ "type":"string", "value" : "5 bedroom  property for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Woodstock Road, London NW11"},
            "description" :{ "type":"string", "value" : "5 bedroom  property for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Tamworth Street, London SW6"},
            "description" :{ "type":"string", "value" : "5 bedroom  property for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Stanhope Avenue, Finchley, London"},
            "description" :{ "type":"string", "value" : "5 bedroom  semi detached house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " The Old Burlington, Church Street, London W4"},
            "description" :{ "type":"string", "value" : "3 bedroom  property for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Ebury Close, Northwood HA6"},
            "description" :{ "type":"string", "value" : "4 bedroom  detached house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Middleton Road, London NW11"},
            "description" :{ "type":"string", "value" : "4 bedroom  property for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Henson Avenue, Willesden Green NW2"},
            "description" :{ "type":"string", "value" : "5 bedroom  property for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Huron Road, London SW17"},
            "description" :{ "type":"string", "value" : "6 bedroom  property for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Corringway, Ealing W5"},
            "description" :{ "type":"string", "value" : "5 bedroom  detached house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Woodlands Avenue, New Malden KT3"},
            "description" :{ "type":"string", "value" : "5 bedroom  detached house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Gunnersbury Park Area, Ealing, London"},
            "description" :{ "type":"string", "value" : "6 bedroom  property for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Blenheim Gardens, London, Brent NW2"},
            "description" :{ "type":"string", "value" : "6 bedroom  property for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Creighton Road, London NW6"},
            "description" :{ "type":"string", "value" : "4 bedroom  terraced house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Plaistow Lane, Bromley BR1"},
            "description" :{ "type":"string", "value" : "7 bedroom  detached house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Greenfield Gardens, London NW2"},
            "description" :{ "type":"string", "value" : "4 bedroom  property for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Hendon Avenue, London N3"},
            "description" :{ "type":"string", "value" : "3 bedroom  detached house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Peckham Park Road, London SE15"},
            "description" :{ "type":"string", "value" : "6 bedroom  semi detached house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Woodclyffe Drive, Chislehurst BR7"},
            "description" :{ "type":"string", "value" : "5 bedroom  house for sale"},
            "listprice" : { "type":"string", "value" : "

                From 1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Highwood Hill, Mill Hill, London"},
            "description" :{ "type":"string", "value" : "5 bedroom  detached house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Stanhope Avenue, London N3"},
            "description" :{ "type":"string", "value" : "5 bedroom  semi detached house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Kersley Mews, London SW11"},
            "description" :{ "type":"string", "value" : "3 bedroom  mews for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Ebury Close, Northwood HA6"},
            "description" :{ "type":"string", "value" : "4 bedroom  detached house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Ellesmere Road, Chiswick W4"},
            "description" :{ "type":"string", "value" : "6 bedroom  detached house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " The Avenue, Hatch End, Pinner, Middlesex"},
            "description" :{ "type":"string", "value" : "5 bedroom  detached house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Wandsworth, London SW18"},
            "description" :{ "type":"string", "value" : "6 bedroom  semi detached house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Carlton Road, New Malden KT3"},
            "description" :{ "type":"string", "value" : "4 bedroom  detached house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " St Mary's Mews, Ealing W5"},
            "description" :{ "type":"string", "value" : "3 bedroom  property for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Ritherdon Road, Balham, London SW17"},
            "description" :{ "type":"string", "value" : "5 bedroom  semi detached house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Goldsmith Avenue, London W3"},
            "description" :{ "type":"string", "value" : "5 bedroom  property for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ,
        {
            "address" : { "type":"string", "value" : " Plaistow Lane, Bromley, Kent BR1"},
            "description" :{ "type":"string", "value" : "7 bedroom  detached house for sale"},
            "listprice" : { "type":"string", "value" : "

                1,250,000


                    "}
        }
    ] } }

Question 34

From the command-line:

echo '{"one":1,"two":2}' | python -mjson.tool

which outputs:

{
    "one": 1, 
    "two": 2
}

Programmtically, the Python manual describes pretty-printing JSON:

>>> import json
>>> print json.dumps({'4': 5, '6': 7}, sort_keys=True, indent=4)
{
    "4": 5,
    "6": 7
}

Question 35

Use the indent argument of the dumps function in the json module.

From the docs:

>>> import json
>>> print json.dumps({'4': 5, '6': 7}, sort_keys=True, indent=4)
{
    "4": 5,
    "6": 7
}

Question 36

A minimal in-python solution that colors json data supplied via the command line:

import sys
import json
from pygments import highlight, lexers, formatters

formatted_json = json.dumps(json.loads(sys.argv[1]), indent=4)
colorful_json = highlight(unicode(formatted_json, 'UTF-8'), lexers.JsonLexer(), formatters.TerminalFormatter())
print(colorful_json)

Inspired by pjson mentioned above. This code needs pygments to be installed.

Output example:

Question 37

Try underscore-cli:

cat myfile.json | underscore print --color

It’s a pretty nifty tool that can elegantly do a lot of manipulation of structured data, execute js snippets, fill templates, etc. It’s ridiculously well documented, polished, and ready for serious use. And I wrote it. :)

Question 38

The cli command I’ve used with python for this is:

cat myfile.json | python -mjson.tool

You should be able to find more info here:

http://docs.python.org/library/json.html

Question 39

It looks like jsbeautifier open sourced their tools and packaged them as Python and JS libs, and as CLI tools. It doesn’t look like they call out to a web service, but I didn’t check too closely. See the github repo with install instructions.

From their docs for Python CLI and library usage:

To beautify using python:

$ pip install jsbeautifier
$ js-beautify file.js

Beautified output goes to stdout.

To use jsbeautifier as a library is simple:

import jsbeautifier
res = jsbeautifier.beautify('your javascript string')
res = jsbeautifier.beautify_file('some_file.js')

…or, to specify some options:

opts = jsbeautifier.default_options()
opts.indent_size = 2
res = jsbeautifier.beautify('some javascript', opts)

If you want to pass a string instead of a filename, and you are using bash, then you can use process substitution like so:

$ js-beautify <(echo '{"some": "json"}')

Question 40

I didn’t like the output of json.dumps(…) -> For my taste way too much newlines. And I didn’t want to use a command line tool or install something. I finally found Pythons pprint (= pretty print). Unfortunately it doesn’t generate proper JSON but I think it is useful to have a user friendly glympse at the stored data.

Output of json.dumps(json_dict, indent=4)

{
    "hyperspace": {
        "constraints": [],
        "design": [
            [
                "windFarm.windparkSize.k",
                "continuous",
                [
                    0,
                    0,
                    5
                ]
            ],
            [
                "hydroPlant.primaryControlMax",
                "continuous",
                [
                    100,
                    300
                ]
            ]
        ],
        "kpis": [
            "frequency.y",
            "city.load.p[2]"
        ]
    },
    "lhc_size": 10,
    "number_of_runs": 10
}

Usage of pprint:

import pprint

json_dict = {"hyperspace": {"constraints": [], "design": [["windFarm.windparkSize.k", "continuous", [0, 0, 5]], ["hydroPlant.primaryControlMax", "continuous", [100, 300]]], "kpis": ["frequency.y", "city.load.p[2]"]}, "lhc_size": 10, "number_of_runs": 10}

formatted_json_str = pprint.pformat(json_dict)
print(formatted_json_str)
pprint.pprint(json_dict)

Result of pprint.pformat(...) or pprint.pprint(...):

{'hyperspace': {'constraints': [],
                'design': [['windFarm.windparkSize.k', 'continuous', [0, 0, 5]],
                           ['hydroPlant.primaryControlMax',
                            'continuous',
                            [100, 300]]],
                'kpis': ['frequency.y', 'city.load.p[2]']},
 'lhc_size': 10,
 'number_of_runs': 10}

Question 41

alias jsonp='pbpaste | python -m json.tool'

This will pretty print JSON that’s on the clipboard in OSX. Just Copy it then call the alias from a Bash prompt.

Question 42

You could pipe the output to jq. If you python script contains something like

print json.dumps(data)

then you can fire:

python foo.py | jq '.'

Question 43

Use the python tool library

Command line: python -mjson.tool

In code: http://docs.python.org/library/json.html

Question 44

First install pygments

then

echo '<some json>' | python -m json.tool | pygmentize -l json

Question 45

Your data is poorly formed. The value fields in particular have numerous spaces and new lines. Automated formatters won’t work on this, as they will not modify the actual data. As you generate the data for output, filter it as needed to avoid the spaces.

Question 46

With jsonlint (like xmllint):

aptitude install python-demjson
jsonlint -f foo.json

Question 47

I’m using Python with -c to execute a one-liner loop, i.e.:

$ python -c "for r in range(10): print 'rob'"

This works fine. However, if I import a module before the for loop, I get a syntax error:

$ python -c "import sys; for r in range(10): print 'rob'"
  File "<string>", line 1
    import sys; for r in range(10): print 'rob'
              ^
SyntaxError: invalid syntax

Any idea how this can be fixed?

It’s important to me to have this as a one-liner so that I can include it in a Makefile.

Question 48

you could do

echo -e "import sys\nfor r in range(10): print 'rob'" | python

or w/out pipes:

python -c "exec(\"import sys\nfor r in range(10): print 'rob'\")"

or

(echo "import sys" ; echo "for r in range(10): print 'rob'") | python

or @SilentGhost’s answer / @Crast’s answer

Question 49

this style can be used in makefiles too (and in fact it is used quite often).

python - <<EOF
import sys
for r in range(3): print 'rob'
EOF

or

python - <<-EOF
    import sys
    for r in range(3): print 'rob'
EOF

in latter case leading tab characters are removed too (and some structured outlook can be achieved)

instead of EOF can stand any marker word not appearing in the here document at a beginning of a line (see also here documents in the bash manpage or here).

Question 50

The issue is not actually with the import statement, it’s with anything being before the for loop. Or more specifically, anything appearing before an inlined block.

For example, these all work:

python -c "import sys; print 'rob'"
python -c "import sys; sys.stdout.write('rob\n')"

If import being a statement were an issue, this would work, but it doesn’t:

python -c "__import__('sys'); for r in range(10): print 'rob'"

For your very basic example, you could rewrite it as this:

python -c "import sys; map(lambda x: sys.stdout.write('rob%d\n' % x), range(10))"

However, lambdas can only execute expressions, not statements or multiple statements, so you may still be unable to do the thing you want to do. However, between generator expressions, list comprehension, lambdas, sys.stdout.write, the “map” builtin, and some creative string interpolation, you can do some powerful one-liners.

The question is, how far do you want to go, and at what point is it not better to write a small .py file which your makefile executes instead?

Question 51

^{– To make this answer work with Python 3.x as well, print is called as a function: in 3.x, only print('foo') works, whereas 2.x also accepts print 'foo'.

– For a cross-platform perspective that includes Windows, see kxr’s helpful answer.}

In bash, ksh, or zsh:

Use an ANSI C-quoted string ($'...'), which allows using \n to represent newlines that are expanded to actual newlines before the string is passed to python:

python -c $'import sys\nfor r in range(10): print("rob")'

Note the \n between the import and for statements to effect a line break.

To pass shell-variable values to such a command, it is safest to use arguments and access them via sys.argv inside the Python script:

name='rob' # value to pass to the Python script
python -c $'import sys\nfor r in range(10): print(sys.argv[1])' "$name"

^{See below for a discussion of the pros and cons of using an (escape sequence-preprocessed) double-quoted command string with embedded shell-variable references.}

To work safely with $'...' strings:

Double \ instances in your original source code.
- \<char> sequences – such as \n in this case, but also the usual suspects such as \t, \r, \b – are expanded by $'...' (see man printf for the supported escapes)
Escape ' instances as \'.

If you must remain POSIX-compliant:

Use printf with a command substitution:

python -c "$(printf %b 'import sys\nfor r in range(10): print("rob")')"

To work safely with this type of string:

Double \ instances in your original source code.
- \<char> sequences – such as \n in this case, but also the usual suspects such as \t, \r, \b – are expanded by printf (see man printf for the supported escape sequences).
Pass a single-quoted string to printf %b and escape embedded single quotes as '\'' (sic).
- Using single quotes protects the string’s contents from interpretation by the shell.
  - That said, for short Python scripts (as in this case) you can use a double-quoted string to incorporate shell variable values into your scripts – as long as you’re aware of the associated pitfalls (see next point); e.g., the shell expands $HOME to the current user’s home dir. in the following command:
    - python -c "$(printf %b "import sys\nfor r in range(10): print('rob is $HOME')")"
  - However, the generally preferred approach is to pass values from the shell via arguments, and access them via sys.argv in Python; the equivalent of the above command is:
    - python -c "$(printf %b 'import sys\nfor r in range(10): print("rob is " + sys.argv[1])')" "$HOME"
- While using a double-quoted string is more convenient – it allows you to use embedded single quotes unescaped and embedded double quotes as \" – it also makes the string subject to interpretation by the shell, which may or may not be the intent; $ and ` characters in your source code that are not meant for the shell may cause a syntax error or alter the string unexpectedly.
  - Additionally, the shell’s own \ processing in double-quoted strings can get in the way; for instance, to get Python to produce literal output ro\b, you must pass ro\\b to it; with a '...' shell string and doubled \ instances, we get:
    python -c "$(printf %b 'import sys\nprint("ro\\\\bs")')" # ok: 'ro\bs'
    By contrast, this does not work as intended with a "..." shell string:
    python -c "$(printf %b "import sys\nprint('ro\\\\bs')")" # !! INCORRECT: 'rs'
    The shell interprets both "\b" and "\\b" as literal \b, requiring a dizzying number of additional \ instances to achieve the desired effect:
    python -c "$(printf %b "import sys\nprint('ro\\\\\\\\bs')")"

To pass the code via stdin rather than -c:

^{Note: I’m focusing on single-line solutions here; xorho’s answer shows how to use a multi-line here-document – be sure to quote the delimiter, however; e.g., <<'EOF', unless you explicitly want the shell to expand the string up front (which comes with the caveats noted above).}

In bash, ksh, or zsh:

Combine an ANSI C-quoted string ($'...') with a here-string (<<<...):

python - <<<$'import sys\nfor r in range(10): print("rob")'

- tells python explicitly to read from stdin (which it does by default). - is optional in this case, but if you also want to pass arguments to the scripts, you do need it to disambiguate the argument from a script filename:

python - 'rob' <<<$'import sys\nfor r in range(10): print(sys.argv[1])'

If you must remain POSIX-compliant:

Use printf as above, but with a pipeline so as to pass its output via stdin:

printf %b 'import sys\nfor r in range(10): print("rob")' | python

With an argument:

printf %b 'import sys\nfor r in range(10): print(sys.argv[1])' | python - 'rob'

Question 52

Any idea how this can be fixed?

Your problem is created by the fact that Python statements, separated by ;, are only allowed to be “small statements”, which are all one-liners. From the grammar file in the Python docs:

stmt: simple_stmt | compound_stmt
simple_stmt: small_stmt (';' small_stmt)* [';'] NEWLINE
small_stmt: (expr_stmt | del_stmt | pass_stmt | flow_stmt |
             import_stmt | global_stmt | nonlocal_stmt | assert_stmt)

Compound statements can’t be included on the same line with other statements via semicolons – so doing this with the -c flag becomes very inconvenient.

When demonstrating Python while in a bash shell environment, I find it very useful to include compound statements. The only simple way of doing this reliably is with heredocs (a posix shell thing).

Heredocs

Use a heredoc (created with <<) and Python’s command line interface option, -:

$ python - <<-"EOF"
        import sys                    # 1 tab indent
        for r in range(10):           # 1 tab indent
            print('rob')              # 1 tab indent and 4 spaces
EOF

Adding the - after << (the <<-) allows you to use tabs to indent (Stackoverflow converts tabs to spaces, so I’ve indented 8 spaces to emphasize this). The leading tabs will be stripped.

You can do it without the tabs with just <<:

$ python - << "EOF"
import sys
for r in range(10):
    print('rob')
EOF

Putting quotes around EOF prevents parameter and arithmetic expansion. This makes the heredoc more robust.

Bash multiline strings

If you use double-quotes, you’ll get shell-expansion:

$ python -c "
> import sys
> for p in '$PATH'.split(':'):
>     print(p)
> "
/usr/sbin
/usr/bin
/sbin
/bin
...

To avoid shell expansion use single-quotes:

$ python -c '
> import sys
> for p in "$PATH".split(":"):
>     print(p)
> '
$PATH

Note that we need to swap the quote characters on the literals in Python – we basically can’t use quote character being interpreted by BASH. We can alternate them though, like we can in Python – but this already looks quite confusing, which is why I don’t recommend this:

$ python -c '
import sys
for p in "'"$PATH"'".split(":"):
    print(p)
'
/usr/sbin
/usr/bin
/sbin
/bin
...

Critique of the accepted answer (and others)

This is not very readable:

echo -e "import sys\nfor r in range(10): print 'rob'" | python

Not very readable, and additionally difficult to debug in the case of an error:

python -c "exec(\"import sys\\nfor r in range(10): print 'rob'\")"

Perhaps a bit more readable, but still quite ugly:

(echo "import sys" ; echo "for r in range(10): print 'rob'") | python

You’ll have a bad time if you have "‘s in your python:

$ python -c "import sys
> for r in range(10): print 'rob'"

Don’t abuse map or list comprehensions to get for-loops:

python -c "import sys; map(lambda x: sys.stdout.write('rob%d\n' % x), range(10))"

These are all sad and bad. Don’t do them.

Question 53

just use return and type it on the next line:

user@host:~$ python -c "import sys
> for r in range(10): print 'rob'"
rob
rob
...

Question 54

$ python2.6 -c "import sys; [sys.stdout.write('rob\n') for r in range(10)]"

Works fine. Use “[ ]” to inline your for loop.

Question 55

The problem is not with the import statement. The problem is that the control flow statements don’t work inlined in a python command. Replace that import statement with any other statement and you’ll see the same problem.

Think about it: python can’t possibly inline everything. It uses indentation to group control-flow.

Question 56

If your system is Posix.2 compliant it should supply the printf utility:

$ printf "print 'zap'\nfor r in range(3): print 'rob'" | python
zap
rob
rob
rob

Question 57

single/double quotes and backslash everywhere:

$ python -c 'exec("import sys\nfor i in range(10): print \"bob\"")'

Much better:

$ python -c '
> import sys
> for i in range(10):
>   print "bob"
> '

Question 58

^{(answered Nov 23 ’10 at 19:48)} I’m not really a big Pythoner – but I found this syntax once, forgot where from, so I thought I’d document it:

if you use sys.stdout.write instead of print (the difference being, sys.stdout.write takes arguments as a function, in parenthesis – whereas print doesn’t), then for a one-liner, you can get away with inverting the order of the command and the for, removing the semicolon, and enclosing the command in square brackets, i.e.:

python -c "import sys; [sys.stdout.write('rob\n') for r in range(10)]"

Have no idea how this syntax would be called in Python :)

Hope this helps,

Cheers!

^{(EDIT Tue Apr 9 20:57:30 2013)} Well, I think I finally found what these square brackets in one-liners are about; they are “list comprehensions” (apparently); first note this in Python 2.7:

$ STR=abc
$ echo $STR | python -c "import sys,re; a=(sys.stdout.write(line) for line in sys.stdin); print a"
<generator object <genexpr> at 0xb771461c>

So the command in round brackets/parenthesis is seen as a “generator object”; if we “iterate” through it by calling next() – then the command inside the parenthesis will be executed (note the “abc” in the output):

$ echo $STR | python -c "import sys,re; a=(sys.stdout.write(line) for line in sys.stdin); a.next() ; print a"
abc
<generator object <genexpr> at 0xb777b734>

If we now use square brackets – note that we don’t need to call next() to have the command execute, it executes immediately upon assignment; however, later inspection reveals that a is None:

$ echo $STR | python -c "import sys,re; a=[sys.stdout.write(line) for line in sys.stdin]; print a"
abc
[None]

This doesn’t leave much info to look for, for the square brackets case – but I stumbled upon this page which I think explains:

Python Tips And Tricks – First Edition – Python Tutorials | Dream.In.Code:

If you recall, the standard format of a single line generator is a kind of one line ‘for’ loop inside brackets. This will produce a ‘one-shot’ iterable object which is an object you can iterate over in only one direction and which you can’t re-use once you reach the end.

A ‘list comprehension’ looks almost the same as a regular one-line generator, except that the regular brackets – ( ) – are replaced by square brackets – [ ]. The major advanatge of alist comprehension is that produces a ‘list’, rather than a ‘one-shot’ iterable object, so that you can go back and forth through it, add elements, sort, etc.

And indeed it is a list – it’s just its first element becomes none as soon as it is executed:

$ echo $STR | python -c "import sys,re; print [sys.stdout.write(line) for line in sys.stdin].__class__"
abc
<type 'list'>
$ echo $STR | python -c "import sys,re; print [sys.stdout.write(line) for line in sys.stdin][0]"
abc
None

List comprehensions are otherwise documented in 5. Data Structures: 5.1.4. List Comprehensions — Python v2.7.4 documentation as “List comprehensions provide a concise way to create lists”; presumably, that’s where the limited “executability” of lists comes into play in one-liners.

Well, hope I’m not terribly too off the mark here …

EDIT2: and here is a one-liner command line with two non-nested for-loops; both enclosed within “list comprehension” square brackets:

$ echo $STR | python -c "import sys,re; a=[sys.stdout.write(line) for line in sys.stdin]; b=[sys.stdout.write(str(x)) for x in range(2)] ; print a ; print b"
abc
01[None]
[None, None]

Notice that the second “list” b now has two elements, since its for loop explicitly ran twice; however, the result of sys.stdout.write() in both cases was (apparently) None.

Question 59

This variant is most portable for putting multi-line scripts on command-line on Windows and *nix, py2/3, without pipes:

python -c "exec(\"import sys \nfor r in range(10): print('rob') \")"

(None of the other examples seen here so far did so)

Neat on Windows is:

python -c exec"""import sys \nfor r in range(10): print 'rob' """
python -c exec("""import sys \nfor r in range(10): print('rob') """)

Neat on bash/*nix is:

python -c $'import sys \nfor r in range(10): print("rob")'

This function turns any multiline-script into a portable command-one-liner:

def py2cmdline(script):
    exs = 'exec(%r)' % re.sub('\r\n|\r', '\n', script.rstrip())
    print('python -c "%s"' % exs.replace('"', r'\"'))

Usage:

>>> py2cmdline(getcliptext())
python -c "exec('print \'AA\tA\'\ntry:\n for i in 1, 2, 3:\n  print i / 0\nexcept:\n print \"\"\"longer\nmessage\"\"\"')"

Input was:

print 'AA   A'
try:
 for i in 1, 2, 3:
  print i / 0
except:
 print """longer
message"""

Question 60

This script provides a Perl-like command line interface:

Pyliner – Script to run arbitrary Python code on the command line (Python recipe)

Question 61

When I needed to do this, I use

python -c "$(echo -e "import sys\nsys.stdout.write('Hello World!\\\n')")"

Note the triple backslash for the newline in the sys.stdout.write statement.

Question 62

I wanted a solution with the following properties:

Readable
Read stdin for processing output of other tools

Both requirements were not provided in the other answers, so here’s how to read stdin while doing everything on the command line:

grep special_string -r | sort | python3 <(cat <<EOF
import sys
for line in sys.stdin:
    tokens = line.split()
    if len(tokens) == 4:
        print("%-45s %7.3f    %s    %s" % (tokens[0], float(tokens[1]), tokens[2], tokens[3]))
EOF
)

Question 63

there is one more option, sys.stdout.write returns None, which keep the list empty

cat somefile.log|python -c "import sys;[line for line in sys.stdin if sys.stdout.write(line*2)]"

Question 64

If you don’t want to touch stdin and simulate as if you had passed “python cmdfile.py”, you can do the following from a bash shell:

$ python  <(printf "word=raw_input('Enter word: ')\nimport sys\nfor i in range(5):\n    print(word)")

As you can see, it allows you to use stdin for reading input data. Internally the shell creates the temporary file for the input command contents.

问题：-m开关的作用是什么？

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简介（TLDR）

初赛

的历史发展 -m

用例

缺点

详细比较

结论

Introduction (TLDR)

Preliminaries

Historical Development of -m

Use Cases

Shortcomings

Detailed Comparisons

Conclusion

问题：pip install -U中的“ -U”选项代表什么

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问题：使用argparse获取选定的子命令

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问题：如何从命令行编译Visual Studio项目？

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问题：如何从IDLE交互式shell运行python脚本？

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问题：如何在Python中美化JSON？

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问题：在单行命令行中执行多行语句？

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任何想法如何解决？

Heredocs

重击多行字符串

批评接受的答案（和其他）

Any idea how this can be fixed?

Heredocs

Bash multiline strings

Critique of the accepted answer (and others)

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的历史发展 `-m`

Historical Development of `-m`