create unix alias for "ssh username@", and I would like to use it for any ip address.   for example,  alias go="username@" usecase: $go 10.1.1.1 ; implement => ssh username@10.1.1.1  Currently if i do $go 10.1.1.1, it is taking extra white space between @ and ip address. how can i remove it?
It's taken me almost 10 years of Linux usage to ask this question. It was all trial and error and random late-night internet surfing.  But people shouldn't need 10 years for this. If I were just starting out with Linux, I'd want to know: When to alias, when to script, and when to write a function?  Where aliases are concerned, I use aliases for very simple operations that don't take arguments.   alias houston='cd /home/username/.scripts/'   That seems obvious. But some people do this:  alias command="bash bashscriptname"   (and add it to the .bashrc file)   Is there a good reason to do that? I'm trying really hard, but I genuinely can't think of any circumstances in which I'd want to do that. So, if there is an edge case where that would make a difference, please answer below.  Because that's where I would just put something in my PATH and chmod +x it, which is another thing that came after years of Linux trial-and-error.  Which brings me to the next topic. For instance, I added a hidden folder (.scripts/) in the home directory to my PATH by just adding a line to my .bashrc (PATH=$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.
How to check who owns the Slack's workspace? I'd like to check who owns (or at least some kind of public profile page) some workspace based on its subdomain (e.g. xyz.slack.com).  Is it possible? One word for someone who always does what he loves I am looking for one word to describe someone who always does what he loves.   Loving means enjoying something very much, free-spirited means not restrained by convention. Is there a hybrid word?   I mean a word that describes someone who is independent and always does what he loves. Please also try to not make the word too esoteric. Also, the word needs to be positive.  How will it be used?  I am submitting an application for college, and they require me to supply a word to describe myself. I have always done what I love. So, I require a word to describe someone who loves what they want. There is no sentence, in particular, just a prompt asking me to describe myself in one word. As human beings, we observe the world in which we live in three dimensions. However, it is certainly theoretically possible that more dimensions exist.  Is there any direct or indirect evidence supporting a fourth dimension? What is the use/meaning of 'swap area' while linux installation? Migrating from Evolution to Thunderbird The sum of powers of two and two's complement – is there a deeper meaning behind this? Probably everyone has once come across the following "theorem" with corresponding "proof": $$\sum_{n=0}^\infty 2^n = -1$$ Proof: $\sum_{n=0}^\infty q^n = 1/(1-q)$. Insert $q=2$ to get the result.  Of course the "proof" neglects the condition on $q$ for this formula, and the sum really diverges. However I now noticed an interesting fact:  If you use two's complement to represent negative numbers on computers, $-1$ is represented by all bits set. Also, sign extending to a larger number of bits (that is, getting the same number in two's complement representation on more bits) works by copying the left-most bit (also known as sign bit) into the additional bits on the left.  Now imagine that formally you sign-extend the number $-1$ to infinitely many bits. What you get is an infinite-to-the-left string of $1$s. Which, using the normal base-2 formula $n = \sum_k b_k 2^k$ (where $b_k$ is the bit k positions from the right, i.e. $b_0$ is the rightmost bit), that infinite string of $1$s translates into exactly the sum above! So in some sense we have an independent re-derivation of that equation.  Now my question is: Is there something deeper behind this? Somehow I cannot imagine it is just coincidential. My current prompt is colorized and edited as so -  #!/bin/bash  # GIT Prompt help if tput setaf 1 &amp;&gt; /dev/null; then     tput sgr0; # reset colors     bold=$(tput bold);     reset=$(tput sgr0);     txtund=$(tput sgr 0 1);     black=$(tput setaf 0);     blue=$(tput setaf 33);     cyan=$(tput setaf 37);     green=$(tput setaf 64);     orange=$(tput setaf 166);     purple=$(tput setaf 125);     red=$(tput setaf 124);     violet=$(tput setaf 61);     white=$(tput setaf 15);     yellow=$(tput setaf 136); else     bold='';     reset="\e[0m";     black="\e[1;30m";     blue="\e[1;34m";     cyan="\e[1;36m";     green="\e[1;32m";     orange="\e[1;33m";     purple="\e[1;35m";     red="\e[1;31m";     violet="\e[1;35m";     white="\e[1;37m";     yellow="\e[1;33m"; fi; ORIG=$PS1 HOST=$HOSTNAME PS1="\[${txtund}${green}\]${HOST}\[\[${reset}\]"; PS1+="\$(prompt_git \"\[${white}\] on \[${violet}\]\")"; PS1+="\[${reset}\]"; PS1+="\[ at - ${orange}\W\]"; PS1+="\[${reset}\]"; PS1+="\[ - \u \]"; PS1+="\n\$ ";   I know that the line  PS1+="[ - \u ]"; will show me my current user. However, I want that section to be red if it is root. All other users should be the default color of gray. Is there a way to change the color in that section based off of current user or should I just declare a variable and use an IF statement to insert that section or a modified section with red as a color?  My expected output is gray named user for all normal users. Root should be red. This is BASH. Sorting grid cells in fishnet grid by location and number using QGIS? I am using QGIS 3.2.0 on a Mac (and also have QGIS 2), and I have a fishnet grid (probably created in Arc) that comprises of nearly 2 million grid cells. As a result, every change I make to the attribute table takes hours, so I can't experiment as I would usually.  I need to label each grid cell such that the north-westernmost cell is "1", and the numbers proceed by rows, until the last number goes into the south-easternmost cell. Using the row-number doesn't work, as that's not how the table is sorted. I've done this before, but cannot remember how. How to animate text over a twisted mesh (or text flowing along an infinity loop) Iterating through a Collection, avoiding ConcurrentModificationException when removing objects in a loop We all know you can't do the following because of ConcurrentModificationException:  for (Object i : l) {     if (condition(i)) {         l.remove(i);     } }   But this apparently works sometimes, but not always. Here's some specific code:  public static void main(String[] args) {     Collection&lt;Integer&gt; l = new ArrayList&lt;&gt;();      for (int i = 0; i &lt; 10; ++i) {         l.add(4);         l.add(5);         l.add(6);     }      for (int i : l) {         if (i == 5) {             l.remove(i);         }     }      System.out.println(l); }   This, of course, results in:  Exception in thread "main" java.util.ConcurrentModificationException   Even though multiple threads aren't doing it. Anyway.  What's the best solution to this problem? How can I remove an item from the collection in a loop without throwing this exception?  I'm also using an arbitrary Collection here, not necessarily an ArrayList, so you can't rely on get. Since 17.10 I got familiar with Wayland and I really need the per-monitor-scaling!  How can I start a wayland session after dist-upgrade to Bionic? There is no option in GDM available out-of-the-box.  I do not see what is described as     The Wayland session will still be available, pre-installed Reduce file size without losing quality I would like to save files in Photoshop but keep them as small as possible.   I use Save for Web (and Devices) and save as a JPEG. Here are the settings I used:     I really do not want to lower the quality settings because I use text and sometimes I see artifacts if the setting is too low.   This produces file sizes of several hundred kilobytes depending on size of image. While this isn't a huge issue these images are used for the web and smaller is better. What are techniques without reducing quality to reduce the file size?   Update:  To add some more information here:   Many of the images I use and create get sent via email. This severally limits what I can do with placing of text using HTML and CSS over the image.   Also I use a variety of fonts. Some I could use for the web using CSS's @font-face but you can run into large file sizes and in some cases you cannot upload the font to the web legally. I could use a service like  but again many fonts I use are not available with Typekit.   Here is an example image: How to apply for US passport card when I already have passport book? I have a US passport book, and I would like to apply for a US passport card (to have in addition to my passport book).  If I apply using form DS-82, submitting my current passport book as proof of citizenship, does it get returned to me still valid, or does it get cancelled?  Is it possible to apply for a passport card using form DS-11 and avoid sending in my current valid passport book (submitting a birth certificate instead)?  I would prefer answers with official sources, which I have not been able to find myself on the US State Dept website or on the forms themselves (which are written quite ambiguously). I've just begun to work learn Linear Algebra on my own through Hoffman and Kunze's book and the first problem set already has a question that I can't solve:  Prove that if two homogeneous systems of linear equations in two unknowns have the same solutions, then they are equivalent.  I can't seem to figure out how to prove this without resorting to case work where you account for the cases where one of the coefficients are zero and when both are.  Is there an elegant way to prove in general that when two systems of linear equations have the same solutions, they are equivalent? The converse is obvious enough though.  Definition of equivalence from the text :     Let us say that two systems of linear equations are equivalent if each equation in each system is a linear combination of the equations   in the other system. Past participle form of "exit"? It would seem that far-away stars are at such a distance that I should be able to take a step to the side and not have the star's photons hit my eye. How do stars release so many photons to fill in such great angular distances? Gravity as a gauge theory Currently, (classical) gravity (General Relativity) is NOT a gauge theory (at least in the sense of a Yang-Mills theory).   Why should "classical" gravity be some (non-trivial or "special" or extended) gauge theory? Should quantum gravity be a gauge theory?  Remark: There are some contradictory claims in the literature to this issue. To what extent gravity is "a gauge" theory?Obviously, GR is not a YM theory. So, why do some people say that gravity "IS" a gauge theory? I found this question relevant, e.g., then we handle GR in the Einstein-Cartan theory or any other theory beyond GR, like teleparallel theories or higher-derivative gravitational theories. So I think it could be useful to discuss the "gauge flavor" of gravity here. When is the present perfect tense used instead of the past tense? When is the present perfect tense used instead of the past tense?    I know that the present perfect tense is used when some adverbs (e.g., never, ever) are present in the sentence; the same is true for sentences like the following one.     When you returned, I have been at home since 3:00 PM.   In which other cases should I use the present perfect? Do the following sentences require it?     I have walked downtown everyday for a year.        I have been at home since 3:00 PM. A different approach in distributing $8$ distinct balls into $6$ distinct boxes Find the number of ways in distributing $8$ distinct balls into $6$ distinct boxes such that there is at least $1$ ball in each box.  We are well acquainted with the traditional Inclusion-Exclusion principle in solving this and it will come up as $191520$ ways.  I tried in this way:  When we distribute $8$ balls into $6$ boxes we have two possible cases  Case $1.$ There are exactly $2$ boxes with $2$ balls each  Case $2.$ There is exactly $1$ Box with $3$ balls in it.  For Case $1$, the distribution is done by choosing $2$ boxes from $6$ boxes and $2$ balls from $8$ balls and those two balls can be arranged in $2!$ ways. But I require another two balls from remaining $6$ balls to be placed in each of these two boxes which can be done in $\binom{6}{2} \times 2!$ ways. Finally remaining $4$ balls can be distributed in remaining $4$ boxes in $4!$ ways. So total number of ways for Case $1.$ is  $$\binom{6}{2} \times \binom{8}{2} \times 2! \times \binom{6}{2} \times 2! \times 4!=604800$$  For Case $2$, the number of ways is  $$\binom{6}{1} \times \binom{8}{3} \times 5!=40320$$  I am pretty sure the value obtained for Case $2.$ is correct. but I could not find where I went wrong in Case $1.$ Minor "you have already raised this type of flag" bug? I flagged something as spam, then was only 90% sure I'd done so, so I clicked the flag link again to check. It showed me this:    I had, of course, only raised the spam flag, not the offensive/abusive/hate flag, so the latter probably shouldn't be saying I did.    Ah, this may be a duplicate, I didn't search enough:        And if so, it's been around a while.