It's recommended to store file into a directory on web server. Why not use a BLOB data type for a column where store files? There are security and consistency advantages and it's easier to manage files doing that. What are the cons?
So I'm using an app that stores images heavily in the DB. What's your outlook on this? I'm more of a type to store the location in the filesystem, than store it directly in the DB.  What do you think are the pros/cons?
Does anyone know if there's a way to get an Android phone to reboot into recovery mode, from the Android command line?  Note:  I do NOT have adb access.  I do NOT know the magic power-on sequence to do it from the boot loader. I've tried the common things and nothing works.  I DO have root. (And can enter commands directly on the device using a terminal emulator.)  I know it's possible, somehow, because applications like ROM Manager do it. But how? Add a rule after chapter title using titlesec Is the cube root of a prime number rational? so there are some idiosyncrasies with the method they use to invert that part of the image which I can't figure out. It could be that they just invert the luminosity but I don't know how i would do that in a dynamic way. Using a java library from python I have a python app and java app. The python app generates input for the java app and invokes it on the command line.  I'm sure there must be a more elegant solution to this; just like using JNI to invoke C code from Java.  Any pointers? (FYI I'm v. new to Python)    Clarification (at the cost of a long question: apologies) The py app (which I don't own) takes user input in the form of a number of configuration files. It then interprits these and farms work off to a number of (hidden) tools via a plugin mechanism. I'm looking to add support for the functionality provided by the legacy Java app.  So it doesn't make sense to call the python app from the java app and I can't run the py app in a jython environment (on the JVM).  Since there is no obvious mechanism for this I think the simple CL invocation is the best solution. On  (but I remember seeing it in other cases) the diff shows the same tag being both added and removed. Actual memory usage of a process The following are the memory usage of mysql and apache respectively on my server. As per the output of pmap say, mysql is using about 379M and apache is using 277M.   [root@server ~]# pmap 10436 | grep total  total           379564K  [root@server ~]# pmap 10515 | grep total  total           277588K   Comparing this with the output of top, I see the values are almost matching.    PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND 10515 apache    20   0  271m  32m 3132 S  0.0  6.6   0:00.73 /usr/sbin/httpd 10436 mysql     20   0  370m  21m 6188 S  0.0  4.3   0:06.07 /usr/libexec/mysqld --basedir=....   Now these values definitely are not the current memory usage of those two processes, since if it were it would've exceeded the 512M ram on my system and I understand the fact that these are the size of the pages assigned to these two processes and not really the size of the memory actively used by them. Now, when we use pmap -x, I see an extra coloumn Dirty which shows far less memory usage for the process. As seen in the example show below, the Dirty coloumn shows 15M as opposed to 379M in the first coloumn. My question is: Is the value under coloumn Dirty is the 'real' amount of memory actively used by that process? If its not, then how can we find out the real memory usage of a process? Not ps and top for the same reasons above. Do we have anything under /proc that will give this info?  [root@server ~]# pmap -x 10436 | grep total total kB          379564   21528   15340 [root@server ~]#   [root@server ~]# free -m              total       used       free     shared    buffers     cached Mem:           489        447         41          0         52        214 -/+ buffers/cache:        180        308 Swap:         1023          0       1023 [root@server ~]# Prove $\det(kA)=k^n\det A$ In Bash, when to alias, when to script, and when to write a function? It's taken me almost 10 years of Linux usage to ask this question. It was all trial and error and random late-night internet surfing.  But people shouldn't need 10 years for this. If I were just starting out with Linux, I'd want to know: When to alias, when to script, and when to write a function?  Where aliases are concerned, I use aliases for very simple operations that don't take arguments.   alias houston='cd /home/username/.scripts/'   That seems obvious. But some people do this:  alias command="bash bashscriptname"   (and add it to the .bashrc file)   Is there a good reason to do that? I'm trying really hard, but I genuinely can't think of any circumstances in which I'd want to do that. So, if there is an edge case where that would make a difference, please answer below.  Because that's where I would just put something in my PATH and chmod +x it, which is another thing that came after years of Linux trial-and-error.  Which brings me to the next topic. For instance, I added a hidden folder (.scripts/) in the home directory to my PATH by just adding a line to my .bashrc (PATH=$PATH:/home/username/.scripts/), so anything executable in there automagically autocompletes.  If I needed to.  I don't really need that, though, do I? I would only use that for languages that are not the shell, like Python.  If it's the shell, I can just write a function inside the very same .bashrc:  funcname () {   somecommand -someARGS "$@" }   As I stated, I found a lot of this out through trial and error. And I only truly saw the beauty of functions when my computer died and I was forced to use the computers of the people around me when they weren't using them.   Instead of moving a whole directory of scripts from computer to computer, I ended up just replacing everyone else's .bashrc with my own, since they had never even made a single modification.  But did I miss anything?   So, what would you tell a beginning Linux user about when to alias, when to script, and when to write a function?   If it's not obvious, I'm assuming the people who answer this will make use of all three options. If you only use aliases, or only use scripts, or only use functions—or if you only use aliases and scripts or aliases and functions or scripts and functions—this question isn't really aimed at you. When moving around the sites on Stack Exchange using Safari on my iPad (not the Stack Exchange App), I am fine when moving to any site other than SuperUser.  When logged in, I can switch sites and stay logged in, but when I switch to Super User I need to log in again. If I choose not to log in and switch to another site, I am logged in there. Is there a problem with the login handling for Super User? If it helps, I log in with a Stack Exchange account, not through Facebook or Google. Update After getting fed up with the problem, I took the advice given in the answer below which was to use Chrome, and the problem still exists. The same goes for Firefox. Have I missed something?  As you can see from the screenshots below, there are no cookie settings to be found. Chrome for iOS settings page  Privacy settings page  Content settings page  Google app settings page How to mount and unmount hard drives under Windows (the unix way) Direct observations of a black hole? I'm not very knowledgeable about physics generally, but know that nothing can escape a black hole's gravitational pull, not even light (making them nearly invisible?).   My question is: What has been obtained from direct observation of a black hole to prove their existence? Please note that I'm not questioning the existence of black holes, but am just curious as to how we have come to realize it. Stack Exchange OpenID credentials not removed on logout, allowing insecure re-login What information does the trace of a matrix give? I was recently thinking what information do we get from a matrix. So if we say the columns (or rows) of a matrix define the basis of a system, say vectors of 3 dimensional space. Then the determinant will tell about the volume of the space enclosed by those vectors. Does trace give any information about the space? How to use the Bevel node in 2.79b Technically, NULL = NULL is False, by that logic no NULL is equal to any NULL and all NULLs are distinct. Shouldnt this imply that all NULLs are unique and a unique index should allow any number of NULLs? "Activity" tab for the Community user's network profile sometimes leads to a server error I want to run a script to simply change the current working directory:  #!/bin/bash cd web/www/project   But, after I run it, the current pwd remains unchanged! How can I do that? How can i restrict /admin login page to a particular IP only? Rules for the usage of "me" VS. "myself"? What are general guidelines for the use of "me" and "myself"?     Did I describe me or did I describe Maria?   OR     Did I describe myself or did I describe Maria?