i want to execute youtube-dl command in python. So that i can save my favorite videos.  Something like that:    import os   youtube-dl any_link
How do you call an external command (as if I'd typed it at the Unix shell or Windows command prompt) from within a Python script?
This  shows the dual cone of $K = \{(x,t) \mid \| \boldsymbol{x} \|_1 \le t \}$ is $K^{*} = \{(x,t) \mid  \| \boldsymbol{x} \|_{\infty} \le t\}$. Is it right? How is it proved? I have created my StackOverflow Careers panel, and when I click 'add a stack overflow account with over 200 reputation' the site decides that I have no StackOverflow account at all, although my current one has over 300. I log in to both with the same StackExchange Account with the same email etc so I'm curious as to why this is happening. Electrostatics and tv screens Composite primary key from multiple tables / multiple foreign keys I want to build a composite primary key made up of foreign keys from two different tables. I'm still pretty green to this...  A great answer was given to building a composite key from multiple foreign keys on  but I want to do this from multiple tables. I am using Oracle 11g.  foreign key (Name, BoughtFrom, TimeBought)    references the_other_table_name (Name, BoughtFrom, TimeBought)   Imagine that the "references" line actually includes multiple tables. I'm not even sure that the above syntax will work with Oracle.  I have one table "Student" and one table "Parent". It is a many-to-many relationship. My association table is named "Relation" and I would like to make a composite primary key from "PAR_ID" and "STU_ID". Both are foreign keys. Practical way to implement prevention of IP Spoofing I am an undergraduate Computer Science student and was hoping to gain some knowledge of ways to help prevent IP spoofing but all the resources I have tried out elaborate this concept in a theoretical way. I want to try out my hands at one of the techniques like:      How do I simulate this whole situation in my own system were I myself am the attacker and I myself have to defend it? And once I have gained an understanding of it, then how do I start translating that into programming terms? How can I compute the number of lists of the form $(a_1,\ldots,a_k)$, where $a_i \geq 0$ are integers and $\sum a_i \leq n$? What is the easiest way to derive the answer? Code after bullet list isn't rendered correctly Possible Duplicate:         If there is a list immediately followed by a code block the code block is not recognized as code (Even though there is a newline between the two).  int answer = 42;  Note: This happens both in the WMD preview and in the final (server rendered) post. Is there a word for colloquial forms of address? For example, "dude," "man," "buddy," "pal," etc, when used to stand in for someone's name.  "Hey, pal, how's it going?"  Is there a word for terms like these?  Or is "colloquialism" as close as we can get? Affiliation for a retiree This question is similar to   and  except that I am a retiree.  I intend to submit a paper to a journal without mentioning any affiliation because I am no longer employeed. I have been thinking about a footnote in the paper indicating I am a retiree from my former employer for two reasons: I am receiving pension from the company pension fund and it is a well-known company in U.S. Using their name may make me look good. On the other hand, I feel like it's cheating because I am not their employee anymore. Browser back leaves page after going fullscreen in stack snippet Opening a Stack Snippet in full screen should use history.pushState() to add an entry to the browser history stack. Clicking back will then close the snippet rather than leave the page completely. number of edges induction proof Proof by induction that the complete graph $K_{n}$ has $n(n-1)/2$ edges.   I know how to do the induction step I'm just a little confused on what the left side of my equation should be. $E = n(n-1)/2$  It's been a while since I've done induction. I just need help determining both sides of the equation. commandButton/commandLink/ajax action/listener method not invoked or input value not set/updated How do I enable or disable Apport? I have a table that looks like this:  +----------------------------------------+ |Name                | kode      | jum   | +----------------------------------------+ | aman               |kode1      | 2     | | aman               |kode2      | 1     | | jhon               |kode1      | 4     | | amir               |kode2      | 4     | +--------------------+-----------+-------+   How can I make a view like this with MySQL?                      kode1    kode2     count aman                  2         1        3   jhon                  0         4        4 amir                  0         4        4 Below you find the design for our business cards. The triangles are yellow, as you can see outside of the canvas. However, inside the canvas, only when I set the Color Mode to CMYK, they appear pink. When I switch the Color Mode back to RGB, they appear yellow as expected. However, when I print them, in both cases they turn out pink...   I would just like to know what is going on here and how I can change them back to the right colors?  CMYK Colors: Replacing NAs with latest non-NA value I am a newbie in linux. I wanted to install ubuntu to my desktop. I currently have two partitions, Windows 8 in installed on one, and i have some important files in another partition. While installing ubuntu, if I chose "Replace Windows 8 with Ubuntu", do I lose the other partition too?   And are there other ways to leave the other partition as it is, and install ubuntu in the partition  where windows was installed. Using Illustrator CS6 to create shape out of multiple paths Unzip a file with php As we all know that Kurama's chakra is of the healing nature type. This is known from many mentions about it in the wiki page of .  My question is, what is the nature type of the chakra of the other Tailed beasts?  Note: This is my thinking why there should have been a nature type to each of the tailed beasts.   As we all know that when Rikudō Sennin was about to die, he split his powers among his two sons (the older son inherited his powerful chakra and spiritual energy, and the younger son inherited his powerful life force and physical energy). Similarly, when creating the nine tailed beasts from the Shinju, he must have split the chakra based on their nature so that each tailed beast had a unique natured chakra.  Any insight on this would be very much welcomed.