user@greeneyes:~$ sudo apt-get install xdotool user is not in the sudoers file.  This incident will be reported. user@greeneyes:~$ su verelse Password:  verelse@greeneyes:/home/user$ su user Password:  user@greeneyes:~$ sudo apt-get install xdotool Reading package lists... Done Building dependency tree        Reading state information... Done The following additional packages will be installed:   libxdo3 The following NEW packages will be installed:   libxdo3 xdotool 0 upgraded, 2 newly installed, 0 to remove and 0 not upgraded. Need to get 61.5 kB of archives. After this operation, 204 kB of additional disk space will be used. Do you want to continue? [Y/n]  Get:1 http://us.archive.ubuntu.com/ubuntu bionic/universe amd64 libxdo3 amd64 1:3.20160805.1-3 [20.5 kB] Get:2 http://us.archive.ubuntu.com/ubuntu bionic/universe amd64 xdotool amd64 1:3.20160805.1-3 [41.0 kB] Fetched 61.5 kB in 0s (136 kB/s)   Selecting previously unselected package libxdo3:amd64. (Reading database ... 168281 files and directories currently installed.) Preparing to unpack .../libxdo3_1%3a3.20160805.1-3_amd64.deb ... Unpacking libxdo3:amd64 (1:3.20160805.1-3) ... Selecting previously unselected package xdotool. Preparing to unpack .../xdotool_1%3a3.20160805.1-3_amd64.deb ... Unpacking xdotool (1:3.20160805.1-3) ... Processing triggers for libc-bin (2.27-3ubuntu1) ... Processing triggers for man-db (2.8.3-2) ... Setting up libxdo3:amd64 (1:3.20160805.1-3) ... Setting up xdotool (1:3.20160805.1-3) ... Processing triggers for libc-bin (2.27-3ubuntu1) ...   this is odd  user@greeneyes:~$ whoami user user@greeneyes:~$ sudo su user is not in the sudoers file.  This incident will be reported. user@greeneyes:~$ su user Password:  user@greeneyes:~$ whoami user user@greeneyes:~$ sudo su root@greeneyes:/home/user#
After I add a user using adduser, I can't see it via System > Administration > Users and Groups unless I log out and then log in again. Is that normal?  Also, can I set a newly added user as a sudoer or do I have to change that only after adding it? How can I do that via the shell?  Finally, can I delete the original user that was created upon initial installation of Ubuntu, or is this user somehow 'special'?
Example of a Subgroup That Is Not Normal Can you kindly provide an example of a subgroup that is not normal?  I have been told many times that, for coset multiplication to be defined, the subgroup must be normal.  I have seen the proof and examples of quotient group multiplications.  Now, I am trying to find out where the process will break down if the subgroup is not normal.  Suppose that $x \in a_1H = a_2H, y \in b_1H = b_2H$, where $H$ is not normal. So $x = a_1h_1 = a_2h_2$ for some $h_1, h_2 \in H$, and $y = b_1h_1^* = b_2h_2^*$ for some $h_1, h_2 \in H$.  $xy = (a_1b_1)(h_1h_1^*) = (a_2b_2)(h_2h_2^*)$.  However, both $h_1h_1^*, h_2h_2^*$ are still elements of $H$.  So I don't see how $a_1b_1H \neq a_2b_2H$. SSH tunnelling with multiple dynamic port forwardings I am trying to monitor multiple JVMs running on different servers through an ssh tunnel.  Thanks to one of the UNIX gurus here, I have managed to get this running for a single server by:   Run jstatd on the target server Set up Visual VM to use 9696 as its socks proxy port. On my local PC, run:  ssh -L 2222:server1:22 bastion-host  On my local PC, run:  ssh -o port=2222 -D 9696 -L 1099:localhost:1099 localhost    This does the trick. Now when I try and tunnel to a second server I try:   On my local PC, run:  ssh -L 3333:server2:22 bastion-host  On my local PC, run:  ssh -o port=3333 -D 9696 -L 2099:localhost:1099 localhost    However, the last step complains with:  bind: Address already in use channel_setup_fwd_listener: cannot listen to port: 9696   Has anyone managed to do something similar?  Update:  The reason this is so complex is that jstatd is an RMI server application:    As with RMI applications, these register with an rmiregistry. Using rmi through a firewall requires me to use SOCKS as described here:    Unfortunately, visualvm only lets me set the SOCKS proxy port once, and the -D option won't allow me to forward the same local port to both servers... Ubuntu 17.10, changing input switching to alt-shift (with gnome-tweaks) creates problem in firefox I recently installed Ubuntu 17.10, and when I tried to set my keyboard layout to change with alt+shift, I hit a . There is  which works, but then it creates an unwanted behaviour on Firefox (perhaps other programs as well).   After setting alt+shift through gnome-tweak-tool as the combination to change language, whenever this combination is pressed within Firefox, it triggers a toggle that Firefox uses to show/hide the Menu Bar (with File/Edit/View etc.), and 'focus' is taken away from wherever the cursor was.   It's very frustrating, because one has to go and click again at the cursor.  The only solution I found was to permanently enable Menu Bar in Firefox because then alt doesn't do anything and I can use it to change languages. But I don't want to have Menu Bar on top always.  I hope you can understand what I'm trying to explain.  Any thoughts? Continuous and bounded imply uniform continuity? How do I enable or disable Apport? How does the size of insert affects the rate of Homologous Recombination in yeast? When performing genetic knockouts in yeast using homologous recombination to replace a target gene sequence via a vector DNA, does the region between the flanking regions in the vector have to be the same length as the site of recombination in the host cell's gene? First Bash Script Problem How to add number of days to today's date? As a part of this script, I need to be able to check if the first argument given matches the first word of file. If it does, exit with an error message; if it doesn't, append the arguments to the file. I understand how to write the if statement, but not how to use grep within a script. I understand that grep will look something like this  grep ^$1 schemas.txt   I feel like this should be much easier than I am making it.  I'm getting an error "too many arguments" on the if statement. I got rid of the space between grep -q and then got an error binary operator expected.   if [ grep -q ^$1 schemas.txt ] then         echo "Schema already exists. Please try again"         exit 1 else         echo "$@" &gt;&gt; schemas.txt fi How are connections differentiated from behind NAT routers? Why a subspace of a vector space is useful How do i prove invertibility of this linear transformation Let $a$ be an element of a group G. Prove that $a$ commutes with each of its conjugates in $G$ iff $a$ belongs to an abelian normal subgroup of $G$.   My Try:  I proved the backward direction. For forward one, given $g\in G, a(gag^{-1})=(gag^{-1})a$. I was trying to prove that $a\in Z(G)$. In order to prove that, I must show that $ag=ga$. But failed. Am I on the right track? Can anybody please give me a hint? I want to try it myself. Use "does" in front of another verb in a question? What time does sound good to you?     What time sounds good to you?    Is there a difference? I came across this problem and I believe Lagrange's theorem is the key to its solution.  The question is:     Let $p$ be an odd prime. Prove that there is some integer $x$ such that $x^2 \equiv −1 \pmod p$ if and only if $p \equiv 1 \pmod 4$.   I appreciate any help.  Thanks. Proof that an integral domain that is a finite-dimensional $F$-vector space is in fact a field How to place a .png texture with transparency over a material Is Myopia Reversible/Curable? Say, I have a script that gets called with this line: ./myscript -vfd ./foo/bar/someFile -o /fizz/someOtherFile  or this one: ./myscript -v -f -d -o /fizz/someOtherFile ./foo/bar/someFile   What's the accepted way of parsing this such that in each case (or some combination of the two) $v, $f, and  $d will all be set to true and $outFile will be equal to /fizz/someOtherFile? If a set is linearly independent, a finite subset of that set is also linearly independent Is the above statement true? If I have already proven that the set is linearly independent, is it automatically given that the subset is also linearly independent? If so, how would I go about showing that as a proof.