I have a file root.ext2 in a iso file. How can I  open and see content of ext2 file in Ubuntu?
How do I create a file of size 10M, format it with ext3 filesystem and then mount it in /media/fuse?  I tried with  mkfs -t ext3 file   then to mount it  mount -t ext3 file /media/fuse   It didn't work because it said that file wasn't a block device. Can anybody help me?
If $n&gt;1$ is an integer, then $\sum \limits_{k=1}^n \frac1k$ is not an integer.  If you know , then you know there must be a prime $p$ between $n/2$ and $n$, so $\frac 1p$ appears in the sum, but $\frac{1}{2p}$ does not. Aside from $\frac 1p$, every other term $\frac 1k$ has $k$ divisible only by primes smaller than $p$. We can combine all those terms to get $\sum_{k=1}^n\frac 1k = \frac 1p + \frac ab$, where $b$ is not divisible by $p$. If this were an integer, then (multiplying by $b$) $\frac bp +a$ would also be an integer, which it isn't since $b$ isn't divisible by $p$.  Does anybody know an elementary proof of this which doesn't rely on Bertrand's Postulate? For a while, I was convinced I'd seen one, but now I'm starting to suspect whatever argument I saw was wrong. Sorting an Array of Objects in PHP In a Specific Order I have two arrays in PHP. The first array ($author_array) is comprised of user_ids in a particular order, like so: (8, 1, 6)  The second array ($user_results) is comprised of an array of objects like so:  Array (     [0] =&gt; stdClass Object         (             [ID] =&gt; 1             [user_login] =&gt; user1         )     [1] =&gt; stdClass Object         (             [ID] =&gt; 6             [user_login] =&gt; user6         )     [2] =&gt; stdClass Object         (             [ID] =&gt; 8             [user_login] =&gt; user8         ) )   I'd like to "sort" the second array so it's in this order, which matches the order of the values in the first array of (8, 1, 6). So it'd look like this:  Array (     [0] =&gt; stdClass Object         (             [ID] =&gt; 8             [user_login] =&gt; user8         )     [1] =&gt; stdClass Object         (             [ID] =&gt; 1             [user_login] =&gt; user1         )     [2] =&gt; stdClass Object         (             [ID] =&gt; 6             [user_login] =&gt; user6         ) )   I'm weak on data structures. How could I do this? :-)  Thanks in advance for your help!  -Bob In Windows 7, How to query times, when the computer was locked? Is there a way to get a list of the following times:  whenever windows is locked (using windows+l combo)  whenever windows is unlocked in the past week?   I've tried poking in the event log, to no avail. Many thanks! FTP client on windows that save session password in encrypted text Filezilla or WinSCP save password in plain text which is unsecured on public machines. Is there any FTP client can save and encrypt password so that people using it only can access to FTP but not able to see password? Thanks! Polygon label repeated for each tile How to add some non-standard font to a website? Using ECDSA keys for encryption I know that ECDSA is used for signature only, but I wonder if I can use the public/private Elliptic Curve keys for encryption too.  I have ECDSA SSH public keys and I wonder if I can use them to encrypt data that only the matching machine could decrypt, writing the proper software.  Pointers welcomed. I'm new to inequalities in mathematical induction and don't know how to proceed further. So far I was able to do this:  $V(1): 1≤1 \text{  true}$  $V(n): n!≤((n+1)/2)^n$  $V(n+1): (n+1)!≤((n+2)/2)^{(n+1)}$  and I've got : $(((n+1)/2)^n)\cdot(n+1)≤((n+2)/2)^{(n+1)}$ $((n+1)^n)n(n+1)≤((n+2)^n)((n/2)+1)$ Show that $U_n:=\left(1+\dfrac{1}{n}\right)^n$, $n\in\Bbb N$, defines a monotonically increasing sequence.   I must show that $U_{n+1}-U_n\geq0$, i.e. $$\left(1+\dfrac{1}{n+1}\right)^{n+1}-\left(1+\dfrac{1}{n}\right)^n\geq0.$$  I am trying to go ahead of this step. How to get a variable name as a string in PHP? Say i have this PHP code:  $FooBar = "a string";   i then need a function like this:  print_var_name($FooBar);   which prints:  FooBar   Any Ideas how to achieve this? Is this even possible in PHP? How do I login to the Gamecenter on PewDiePie's Tuber Simulator, if you have not done it when they asked? Uncertainty principle and multiple observers Are shell scripts sensitive to encoding and line endings? There is a bar of chocolate of size $N$ x $M$. Little square $(x, y)$ is poisoned. There are 2 players taking turns. In each move they can cut the bar along any of the horizontal or vertical lines, then the part which does not contain $(x, y)$ is being eaten. The player who is left only with square $(x, y)$ loses (beacause it is poisoned). Which player has the winning strategy? I guess that this game is equivalent to game of Nim due to Sprauge-Grundy theorem, but I don't know how. Meta duplicates don't require an answer. Don't suggest there is one when that's not true If $\sum a_n$ converges and $b_n=\sum\limits_{k=n}^{\infty}a_k $, prove that $\sum \frac{a_n}{b_n}$ diverges Let $\displaystyle \sum a_n$ be  convergent series of positive terms and set  $\displaystyle b_n=\sum_{k=n}^{\infty}a_k$ , then prove that $\displaystyle\sum \frac{a_n}{b_n}$ diverges.   I could see that $\{b_n\}$ is monotonically decreasing sequence converging to $0$ and I can write $\displaystyle\sum \frac{a_n}{b_n}=\sum\frac{b_n-b_{n+1}}{b_n}$, how shall I proceed further? How does someone get to cast more than 40 votes in a day? And by someone, I mean that evil feline WesleyDavid:        That screenshot was taken just before 4pm PST, i.e. just before 0000 UTC.  That shows KittehHead's votes for the month, which is the same as for the day since it's March 1st.  Just to be sure it wasn't that SE had the time wrong, I tried upvoting something and got the expected "Daily Vote Limit Reached, Please Vote Again in 6 minutes."  So how did Kitteh^H^H^H^H^H^HWesley get 42 votes in one day?  ADDED: It's getting worse... Now it's March 2nd, and Wesley/Cat has 3 extra votes:        Now I finally got an extra vote (take that evil kitteh!), but it hasn't helped me understand why: Why am I getting "No such file or directory" when I try to execute a binary? Do the 3 Doctors remember that they saved Gallifrey after 'Day of the Doctor'? I've read several posts and I've seen one that says before it was Eleven's turn to take part in the events of 'Day of the Doctor', Gallifrey was most certainly destroyed, and when it came to his turn he re-wrote history and saved Gallifrey. But I've rewatched 'Day of the Doctor' recently and the War Doctor asks if he'll remember saving Gallifrey and the Doctor says no. So I'm a bit confused, I don't want to think that the War Doctor or the 10th Doctor have lost their memories after saving Gallifrey and their life of saying they destroyed Gallifrey was a lie. So did they really remember? Density of finite rank operator in compact operators on Hilbert spaces