No error , No gain

질문자 :Weiwei Yang쉘 프로그램을 작성할 때 /bin/sh 및 /bin/bash 자주 사용합니다. 나는 보통 bash 사용하지만 그들 사이의 차이점이 무엇인지 모르겠습니다. bash 와 sh 의 주요 차이점은 무엇입니까? bash 와 sh 프로그래밍할 때 알아야 할 사항은 무엇입니까?sh가 뭐야? sh (또는 Shell Command Language)는POSIX 표준에서 설명하는 프로그래밍 언어입니다. 많은 구현이 있습니다( ksh88 , dash , ...). bash sh 의 구현으로 간주될 수도 있습니다(아래 참조). sh 는 구현이 아니라 사양이기 때문에 /bin/sh 는 대부분의 POSIX 시스템에서 실제 구현에 대한 심볼릭 링크(또는 하드 링크)입니다. bash 란 무엇입니까? bas..

The command git add [--all|-A] appears to be identical to git add .. Is this correct? If not, how do they differ? This answer only applies to Git version 1.x. For Git version 2.x, see other answers. Summary: git add -A stages all changes git add . stages new files and modifications, without deletions (on the current directory and its subdirectories). git add -u stages modifications and deletions..

How do I concatenate two lists in Python? Example: listone = [1, 2, 3] listtwo = [4, 5, 6] Expected outcome: >>> joinedlist [1, 2, 3, 4, 5, 6] You can use the + operator to combine them: listone = [1,2,3] listtwo = [4,5,6] joinedlist = listone + listtwo Output: >>> joinedlist [1,2,3,4,5,6] Daniel G Python >= 3.5 alternative: [*l1, *l2] Another alternative has been introduced via the acceptance o..

I am looking for a simple Git command that provides a nicely formatted list of all files that were part of the commit given by a hash (SHA-1), with no extraneous information. I have tried: git show a303aa90779efdd2f6b9d90693e2cbbbe4613c1d Although it lists the files, it also includes unwanted diff information for each. Is there another git command that will provide just the list I want, so that ..

I know that I can do: try: # do something that may fail except: # do this if ANYTHING goes wrong I can also do this: try: # do something that may fail except IDontLikeYouException: # say please except YouAreTooShortException: # stand on a ladder But if I want to do the same thing inside two different exceptions, the best I can think of right now is to do this: try: # do something that may fail e..

Is there a way to make the following return true? string title = "ASTRINGTOTEST"; title.Contains("string"); There doesn't seem to be an overload that allows me to set the case sensitivity.. Currently I UPPERCASE them both, but that's just silly (by which I am referring to the i18n issues that come with up- and down casing). UPDATE This question is ancient and since then I have realized I asked f..

Do Android devices have a unique ID, and if so, what is a simple way to access it using Java? Settings.Secure#ANDROID_ID returns the Android ID as an unique for each user 64-bit hex string. import android.provider.Settings.Secure; private String android_id = Secure.getString(getContext().getContentResolver(), Secure.ANDROID_ID); Also read Best practices for unique identifiers: https://developer...

Is it possible to add a key to a Python dictionary after it has been created? It doesn't seem to have an .add() method. You create a new key/value pair on a dictionary by assigning a value to that key d = {'key': 'value'} print(d) # {'key': 'value'} d['mynewkey'] = 'mynewvalue' print(d) # {'key': 'value', 'mynewkey': 'mynewvalue'} If the key doesn't exist, it's added and points to that value. If..

Optimizing SQLite is tricky. Bulk-insert performance of a C application can vary from 85 inserts per second to over 96,000 inserts per second! Background: We are using SQLite as part of a desktop application. We have large amounts of configuration data stored in XML files that are parsed and loaded into an SQLite database for further processing when the application is initialized. SQLite is idea..

For a web page that exists, but for which a user does not have sufficient privileges (they are not logged in or do not belong to the proper user group), what is the proper HTTP response to serve? 401 Unauthorized? 403 Forbidden? Something else? What I've read on each so far isn't very clear on the difference between the two. What use cases are appropriate for each response? A clear explanation f..

This question already has answers here: How do I get my Python program to sleep for 50 milliseconds? (6 answers) Closed 1 year ago. I would like to know how to put a time delay in a Python script. import time time.sleep(5) # Delays for 5 seconds. You can also use a float value. Here is another example where something is run approximately once a minute: import time while True: print("This prints ..

While using new_list = my_list, any modifications to new_list changes my_list every time. Why is this, and how can I clone or copy the list to prevent it? With new_list = my_list, you don't actually have two lists. The assignment just copies the reference to the list, not the actual list, so both new_list and my_list refer to the same list after the assignment. To actually copy the list, you hav..

I wanted to create a list of options for testing purposes. At first, I did this: ArrayList places = new ArrayList(); places.add("Buenos Aires"); places.add("Córdoba"); places.add("La Plata"); Then, I refactored the code as follows: ArrayList places = new ArrayList( Arrays.asList("Buenos Aires", "Córdoba", "La Plata")); Is there a better way to do this? It would be simpler if you were to just dec..

How can I make two decorators in Python that would do the following? @makebold @makeitalic def say(): return "Hello" ...which should return: "Hello" I'm not trying to make HTML this way in a real application - just trying to understand how decorators and decorator chaining works. If you are not into long explanations, see Paolo Bergantino’s answer. Decorator Basics Python’s functions are objects..

I'm using this code to get standard output from an external program: >>> from subprocess import * >>> command_stdout = Popen(['ls', '-l'], stdout=PIPE).communicate()[0] The communicate() method returns an array of bytes: >>> command_stdout b'total 0\n-rw-rw-r-- 1 thomas thomas 0 Mar 3 07:03 file1\n-rw-rw-r-- 1 thomas thomas 0 Mar 3 07:03 file2\n' However, I'd like to work with the output as a no..

How do I copy a file in Python? I couldn't find anything under os. shutil has many methods you can use. One of which is: from shutil import copyfile copyfile(src, dst) # 2nd option copy(src, dst) # dst can be a folder; use copy2() to preserve timestamp Copy the contents of the file named src to a file named dst. Both src and dst need to be the entire filename of the files, including path. The de..

How do I unit test (using xUnit) a class that has internal private methods, fields or nested classes? Or a function that is made private by having internal linkage (static in C/C++) or is in a private (anonymous) namespace? It seems bad to change the access modifier for a method or function just to be able to run a test. Update: Some 10 years later perhaps the best way to test a private method, ..

This question's answers are a community effort. Edit existing answers to improve this post. It is not currently accepting new answers or interactions. For example, if passed the following: a = [] How do I check to see if a is empty? if not a: print("List is empty") Using the implicit booleanness of the empty list is quite pythonic. Patrick The pythonic way to do it is from the PEP 8 style guide ..

I have an Activity in Android, with two elements: EditText ListView When my Activity starts, the EditText immediately has input focus (flashing cursor). I don't want any control to have input focus at startup. I tried: EditText.setSelected(false); EditText.setFocusable(false); No luck. How can I convince the EditText to not select itself when the Activity starts? Excellent answers from Luc and M..

I want to disable the resizable property of a textarea. Currently, I can resize a textarea by clicking on the bottom right corner of the textarea and dragging the mouse. How can I disable this? The following CSS rule disables resizing behavior for textarea elements: textarea { resize: none; } To disable it for some (but not all) textareas, there are a couple of options. You can use class attribu..