i have created user jagtar &amp; given sudo access from root with usermod -aG sudo jagtar  but  jagtar@wms:~$ $ sudo apt-get install python3-pip python3-dev libpq-dev nginx $: command not found jagtar@wms:~$ which sudo /usr/bin/sudo jagtar@wms:~$ echo $PATH /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin   while basic sudo commands are working  jagtar@wms:~$ sudo apt upgrade Reading package lists... Done Building dependency tree        Reading state information... Done Calculating upgrade... Done The following packages were automatically installed and are no longer required:   app-install-data apt-transport-https cpp-5 espeak-data ethtool   evolution-data-server-online-accounts fonts-stix gconf2-common hardening-includes   hwdata libandroid-properties1 libapparmor-perl libapr1 libaprutil1   libaprutil1-dbd-mysql libaprutil1-ldap libasprintf0v5 libbabeltrace-ctf1   libboost-date-time1.58.0 libboost-iostreams1.58.0 libboost-system1.58.0   libcapnp-0.6.1 libcgmanager0 libdata-alias-perl libdbusmenu-gtk4 libdns162   libespeak1 libevent-2.0-5 libfcitx-gclient0 libfwupd1 libgdbm3   libgnome-desktop-3-12 libgom-1.0-common libgrilo-0.2-1 libgtkspell3-3-0   libgtop-2.0-10 libgweather-3-6 libhardware2 libhud2 libhunspell-1.3-0 libhybris   libhybris-common1 libical1a libisc160 libisccc140 libisccfg140 libisl15   liblircclient0 liblouis9 liblouisutdml6 liblua5.2-0 libmedia1 libmpfr4   libmysqlclient20 libnm-glib-vpn1 libnm-gtk-common libnma-common liborcus-0.10-0v5   libp11-kit-gnome-keyring libpackagekit-glib2-16 libpcre16-3 libpoppler58   libportaudio2 libpython3.5 libqmi-glib1 libqt5feedback5 libqt5multimedia5   libqt5organizer5 libqt5positioning5 libqt5printsupport5 libqt5sensors5   libqt5test5 libquvi-scripts libquvi7 libreoffice-gtk libreoffice-gtk2   libsignon-extension1 libsignon-plugins-common1 libsignon-qt5-1 libtcl8.6   libtxc-dxtn-s2tc0 libvpx3 libwayland-egl1-mesa libwebp5 libwebpmux1   libwinpr-dsparse0.1 libwinpr-heap0.1 libwinpr-input0.1 libwinpr-interlocked0.1   libwinpr-library0.1 libxapian22v5 mysql-common oxideqt-codecs pkg-config   plainbox-provider-resource-generic plainbox-secure-policy pm-utils   python3-checkbox-support python3-jinja2 python3-padme python3-pycurl   python3-pyparsing python3-xlsxwriter signon-keyring-extension   signon-plugin-oauth2 signon-plugin-password signon-ui-service signond tcl8.6 tcpd   ubuntu-mobile-icons ubuntu-ui-toolkit-theme Use 'sudo apt autoremove' to remove them.
Any command that starts with $ returns  command not found   How can I fix this?  I am  using 16.10 Ubuntu.
Add a binary to my path I have an executable. I want to execute the executable in terminal with name only like other commands.  I can put my executable in /usr/local/bin or I could add its PATH to ~/.bashrc. Both will work.  What is better?  Is there  any difference? Tiny white very hard cell bug! Please help to identify! I found these bugs walking on the floor/ wall and on my laptop.  And unfortunately I think they could be in my bed, too, since I bring my laptop to bed sometimes.   I live in a big city in the Netherlands without pets. My house has humidity issues.  I have noticed that the bugs are very tough to exterminate; meaning that when trying to squeeze them it really needs a lot of effort for their size. Their size is about 1 - 2 mm and their color is whitish.    Please note that my lightbulb is having a yellow color.so it makes it look darker than normal. It's more white than looks in the picture          This is a pic of it walking on my screen... How does a cell phone charger work? I have studied that there is a transformer which steps down the ac voltage after then bridge rectifier to convert into ac to dc and then given to filter, this is what I have learnt in books, but when I open a mobile charger I couldn't figure it out how it actually works? I created the following script:  #!bin/bash cat &gt; Top10 &lt;&lt;EOF Linux Mint 17.2 Ubuntu 15.10 Debian GNU/Linux 8.2 Mageria 5 Fedora 23 openSUSE Leap 42.1 Arch Linux CentOS 7.2-1511 PCLinuxOS 2014.12 Slackware Linux 14.1 FreeBSD EOF sed -ri "s/^[^0-9]*$//" Top10 sed -r "s/(.*)([[:space:]][[:digit:]]*.*)$/\2\1/" Top10 | sed -r "s/([[:space:]])([[:digit:]])/\2/" | sed -r "s/([[:digit:]])([[:alpha:]])/\1 \2/" &gt; Top10 sed -r -i "s/(.*)/\L\1/" Top10 sed -r -i "y/[aeiou]/[AEIOU]/" Top10 sort Top10 -g -o Top10 cat Top10   When I run it a few times the following happens:     As you can see sometimes the Top10 file turns out empty and sometimes it turn out the way I needed it to be. I know that the command which replaces the extensions from the end to the front of a line is done poorly. I ran this script on a VMware virtual machine. Could that be the reason? Removing control chars (including console codes / colours) from script output I can use the "script" command to record an interactive session at the command line.  However, this includes all control characters and colour codes.  I can remove control characters (like backspace) with "col -b", but I can't find a simple way to remove the colour codes.  Note that I want to use the command line in the normal way, so don't want to disable colours there - I just want to remove them from the script output.  Also, I know can play around and try find a regexp to fix things up, but I am hoping there is a simpler (and more reliable - what if there's a code I don't know about when I develop the regexp?) solution.  To show the problem:   spl62 tmp: script Script started, file is typescript spl62 lepl: ls add-licence.sed  build-example.sh  commit-test         push-docs.sh add-licence.sh   build.sh          delete-licence.sed  setup.py asn              build-test.sh     delete-licence.sh   src build-doc.sh     clean             doc-src             test.ini spl62 lepl: exit Script done, file is typescript spl62 tmp: cat -v typescript Script started on Thu 09 Jun 2011 09:47:27 AM CLT spl62 lepl: ls^M ^[[0m^[[00madd-licence.sed^[[0m  ^[[00;32mbuild-example.sh^[[0m  ^[[00mcommit-test^[[0m         ^[[00;32mpush-docs.sh^[[0m^M ^[[00;32madd-licence.sh^[[0m   ^[[00;32mbuild.sh^[[0m          ^[[00mdelete-licence.sed^[[0m  ^[[00msetup.py^[[0m^M ^[[01;34masn^[[0m              ^[[00;32mbuild-test.sh^[[0m     ^[[00;32mdelete-licence.sh^[[0m   ^[[01;34msrc^[[0m^M ^[[00;32mbuild-doc.sh^[[0m     ^[[00;32mclean^[[0m             ^[[01;34mdoc-src^[[0m             ^[[00mtest.ini^[[0m^M spl62 lepl: exit^M  Script done on Thu 09 Jun 2011 09:47:29 AM CLT spl62 tmp: col -b &lt; typescript  Script started on Thu 09 Jun 2011 09:47:27 AM CLT spl62 lepl: ls 0m00madd-licence.sed0m  00;32mbuild-example.sh0m  00mcommit-test0m         00;32mpush-docs.sh0m 00;32madd-licence.sh0m   00;32mbuild.sh0m          00mdelete-licence.sed0m  00msetup.py0m 01;34masn0m              00;32mbuild-test.sh0m     00;32mdelete-licence.sh0m   01;34msrc0m 00;32mbuild-doc.sh0m     00;32mclean0m             01;34mdoc-src0m             00mtest.ini0m spl62 lepl: exit  Script done on Thu 09 Jun 2011 09:47:29 AM CLT Proving that $G$ is a group if $a*x=b$ and $y*a=b$ have solutions. (Reference : Fraleigh, A first course in abstract algebra)     Prove that a nonempty set $G$, together with an associative binary operation * on $G$ such that $a*x=b$ and $y*a=b$ have solutions in G, $\forall a,b\in G$, is a group.   Because * is an associatie operation, we have to prove that: there exists $e\in G$ such that $e*a=a=a*e$ for any $a\in G$, and that for any $a\in G$ there exists $\alpha \in G$ such that $a*\alpha=e=\alpha *a$.  This is very confusing, first I tried to prove the identity exists. If we consider a=b, then $a*x=a=y*a$, and because of the hypothesis $x,y\in G$ always exists, now we have to show that $x=y$, but I just can't do this with out inverses, so I tried to prove that the inverses exists, however I have no idea how the identity looks like, I'm stuck.  And I tried to get unstuck, so I thought particular cases, first if $G$ had only one element, then what would happend if it had just two elements... but I remembered that we don't know if G is finite or not, and I think this makes things a little bit more complicated.  What can I do? What is difference between the different 'flavours' of neutrinos? How to prevent form from being submitted? How to resolve merge conflicts in Git repository? What does this depiction of a black hole in the movie Interstellar mean? Change the passphrase of an ecryptfs directory Finding an item in a List using C# How can a company use money from stock investors when they are constantly being bought and sold? One post with multiple questions or multiple posts? I want to ask several questions about the same problem domain but each question is independent from the others. Should I put all the questions in a single post or should I split them and send multiple posts? When transiting Moscow (SVO), citizens of which countries need a transit visa? Insert a full page image How can I insert a full page image?  No blank space left in the page.  Bonus:  How can I add some text over the image? Prove that $\left (\frac{1}{a}+1 \right)\left (\frac{1}{b}+1 \right)\left (\frac{1}{c}+1 \right) \geq 64.$ Let $a,b,$ and $c$ be positive numbers with $a+b+c = 1$. Prove that $$\left (\dfrac{1}{a}+1 \right)\left (\dfrac{1}{b}+1 \right)\left (\dfrac{1}{c}+1 \right) \geq 64.$$   Attempt  Expanding the LHS we obtain $\left (\dfrac{1+a}{a} \right)\left (\dfrac{1+b}{b} \right)\left (\dfrac{1+c}{c} \right)$. We are given that $a+b+c = 1$, so substituting that in we get $\left (\dfrac{b+c+2a}{a} \right)\left (\dfrac{a+c+2b}{b} \right)\left (\dfrac{a+b+2c}{c} \right)$. Then do I say $\left (\dfrac{b+c+2a}{a} \right)\left (\dfrac{a+c+2b}{b} \right)\left (\dfrac{a+b+2c}{c} \right) \geq 64$ and see if I can get a true statement from this? window-switching keyboard shortcuts interfere with emacs and cannot be changed in the main keyboard system preferences Properly discontinuous actions and discrete groups in complete Riemannian manifolds. I was reading the article "The Geometries of 3-manifolds" by Peter Scott and in the end of page 406 he states the following:     If $G$ acts properly discontinuously on a space $X$, then $G$ is a   discrete subset of the space of all continuous functions $X \to X$   with the compact-open topology. The converse is false, in general, but   is true if $X$ is a complete Riemannian manifold and $G$ is a group of   isometries of $X$.   How do I prove the last statement?     If $X$ is a complete Riemannian manifold and   $G$ is a group of isometries of $X$ acting properly discontinuously on $X$, then $G$ is discrete.    Observation: We say a group $G$ of homeomorphisms of $X$ acts properly discontinuously on $X$ if for every compact $K \subset X$ the set $$\{g \in G: gK \cap K \neq \emptyset\}$$ is finite. Restoring backups failing Ubuntu 16.04