I use the "gogs" self-hosted git service, but I want to change to a more active fork called . The  say I should create a user (e.g. git) dedicated for use by gitea:  adduser \   --system \   --shell /bin/bash \   --gecos 'Git Version Control' \   --group \   --disabled-password \   --home /home/git \   git   I currently use gogs in windows, without a special user. Now I want to use gitea in linux, hence my confusion - I assume it's because I might not understand daemons in general.  In windows, when I want to start the service, I run it, and it stays open either in a terminal window or as a background service, until I stop it. In linux I can do the same, so why do I need a dedicated user?  I assume the same practice is used for other services as well, so I need to understand the implications of using / not using a dedicated user for a service.  (I guess this is related to running a service without a user logging on and starting it. But lots of other services are already running and they do not need dedicated users, do they?)
I would like to know difference between user and service account.  I know that e.g. Jenkins installed to ubuntu is not a user, .    What is use of service account? When we need them? How can I create service account?
Printing out Prime Numbers from 2 to 1000 Why do students go for a PhD even when chances of getting academic jobs on its completion are slim? This is in reference to my question: .  I was told in the answer of the above linked question that chances of landing a job as an assistant professor in Mathematics are quite slim. Very few people will actually get a permanent position in academia.  An article of 2014 shows only 0.5-3% of PhD graduates will actually get a job as an Assistant Professor.  But I have two questions:        Why do so many people still apply for a PhD in some reputed institutes in India even knowing the harsh reality? I found there are 1500 applications for four PhD scholarship positions.          One answer says that people move to industry, but I still don’t understand how after doing a PhD in suppose differential geometry or algebraic geometry one can do a job in industry if he/she gets no position as an assistant professor.   Will one be satisfied to do some managerial work in some Consultancy firm after doing a PhD in Mathematics?      Are people jobless after a PhD?   Completion of a PhD requires so much effort. So why is there no value after doing it?      NOTE:  In the most up-voted answer below it has been said that many who enroll for  a PhD don't even wish to pursue an academic career.  I have been asking my seniors who are currently pursuing a PhD or are in the verge of completing their degree or who have completed it. They said that they all want to be Professors in some Universities and want to be involved in research because that is the dream job for them.  I am obviously talking about PhD in Mathematics Why were the villagers and the axe-wielding hitman brothers crawling towards a shrine? At the start of Season 3 Breaking Bad, we see a bunch of villagers and Tuco's cousins crawling on their bellies towards some shrine where they put a drawing of Walter White as some kind of "offering".  Why were the villagers and the cousins crawling towards this shrine? Show that f(x) = inf{g(x1)+h(x2)} is convex subject to x1+x2=x and where g(.) and h(.) are convex functions.  Can I just go about this by using the regular definition of a convex function or which properties should I use? I know that the sum of convex functions is convex, but the infimum part confuses me. Thank you I was reading a bit of Landau and Lifshitz's Mechanics the other day and ran into the following part, where the authors are about to derive the kinetic energy of a free particle. They use the fact that the Lagrangian of this particle must be the same (or at most, differ by the total time derivative of a function of co-ordinates and time) in different inertial frames.     We have $L'=L(v'^2)=L(v^2+2\mathbf{v}\cdot\boldsymbol{\epsilon}+\boldsymbol{\epsilon}^2)$. Expanding this expression in powers of $\boldsymbol{\epsilon}$ and neglecting terms above the first order, we obtain    $$L(v'^2)=L(v^2)+\frac{\partial L(v^2)}{\partial (v^2)}2\mathbf{v}\cdot\boldsymbol{\epsilon}.$$   I think I'm ok with all the physics in this section. What I don't get is just the part I quoted above (so maybe this post is better suited for the math site, but since this is book is so physics-y I thought I'd post it here). My math is pretty rusty, so I'm not really sure- how do the authors expand the function to arrive at the above expression? It reminds me a bit of a Taylor expansion, but not very much. What's the process used to arrive at it? Is it possible to conditionally format a cell if the cell contains formula (to alert myself and other users when updating the cell)? Missing Microsoft.Data.Services.Client version 5.6 on Azure Websites This next year, I am helping an effort to clean several SQL Server environments.    We have about 10,000 stored procedures and estimate that only about 1000 of them are used on a regular basis, and another 200 or so are used on a rare occasion, meaning we have a lot of work to do.    Since we have multiple departments and teams that can access these databases and procedures, we are not always the ones calling the procedures, meaning that we must determine what procedures are being called.  On top of that, we want to determine this over a few months, not in a few days (which eliminates some possibilities).  One approach to this is to use the SQL Server Profiler and track what procedures are being called and compare them to the list of what procedures we have, while marking whether the procedures are used or not.  From then, we could move the procedures to a different schema in case a department comes screaming.  Is using the Profiler the most effective approach here?  And/Or have any of you done something similar and found another way/better way to do this? Automatically make or update a copy real-time on another hard drive volume whenever files are saved to a particular folder InDesign CS5 tables: Can I automatically fit rows or columns to the size of content? You know how Excel has the function "Autofit," where you select a whole row or a whole column and it resizes the entire thing to the height or depth of the largest content item? I want to do that in an InDesign table, but with one click. (I know I can drag the column out until the overflow box goes away, but I want to know if there's some automated function I'm overlooking.) Does this automatic function exist anywhere? Visualization for Euclidean Algorithm I installed the  on my Ubuntu&nbsp;11.04 (Natty Narwhal) with   sudo apt-get install lamp-server^   Now I navigate to /var/www and use   wget http://ftp.drupal.org/files/projects/drupal-7.x-dev.tar.gz   I get the following error.   --2011-08-03 13:59:00--   http://ftp.drupal.org/files/projects/drupal-7.x-dev.tar.gz Resolving  ftp.drupal.org... 64.50.233.100, 64.50.236.52 Connecting to  ftp.drupal.org|64.50.233.100|:80... connected. HTTP request sent,  awaiting response... 200 OK Length: 2757101 (2.6M)  [application/x-gzip] drupal-7.x-dev.tar.gz: Permission denied   Cannot write to `drupal-7.x-dev.tar.gz' (Permission denied).   How do I resolve this error?  I tried to download the same file in the downloads folder, and it went on without an issue. So it seems to be some permission error, but I'm not sure about that or how to solve it. I have both Windows 7 and Ubuntu installed on a shared machine. Because a lot of the non-developers use Windows, I'd like to change the boot order to make it easier for them.  Currently the boot order looks like the following:   Ubuntu 11.10 kernelgeneric *86 Ubuntu 11.10 kernelgeneric *86 (safe boot)  Memory test Memory test Windows 7 on /dev/sda6   How do I change the default order so that Windows 7 is at the top of the list?   Windows 7 on /dev/sda6 Ubuntu 11.10 kernelgeneric *86 Ubuntu 11.10 kernelgeneric *86 (safe boot)  Memory test Memory test How to create an extruded halftone effect in illustrator or photoshop How to get RGB values from UIColor? What is wrong with my date regex? restore table from .frm and .ibd file? I have previously saved a copy of /var/lib/mysql/ddms directory ("ddms" is the schema name). Now I installed a new MySQL on a freshly installed Ubuntu 10.04.3 LTS by running apt-get install mysql-server, I believe version 5.1 was installed. After I copy the ddms directory under /var/lib/mysql, some of its tables work fine, these are the tables with an associated set of three files: a .frm file, a .MYD file and a .MYI file.  However, there are two tables with a different set of files: a .frm file and a .ibd file. These two tables didn't show up in the table list in phpMyAdmin. When I look at the error log, it says:  [ERROR] Cannot find or open table ddms/dictionary_item from the internal data dictionary of InnoDB though the .frm file for the table exists. Maybe you have deleted and recreated InnoDB data files but have forgotten to delete the corresponding .frm files of InnoDB tables, or you have moved .frm files to another database? or, the table contains indexes that this version of the engine doesn't support.   Please help with restoring these two tables. Thanks. What is the autocorrelation for a random walk? Seems like it is really high, but this is counterintuitive to me. Can somebody please explain? I am very confused by this issue and would appreciate a detailed, insightful explanation. Thanks a lot in advance! Complex differential equation How do I solve $$x'=e^{it}\overline{x}?$$  This is a complex differential equation, but I don't see how to solve it.  Edit: the original ODE is given by $$(x', y')=\begin{pmatrix}\cos t&amp; \sin t\\ \sin t&amp;-\cos t\end{pmatrix}(x,y)$$ I want to show that solutions of this ODE do not remain bounded for all $t$, and the idea was to solve the complex equation. having bracket in front of an item