在 Ubuntu 中安装 npm

Question

I am truly struggling to install npm . I have installed the nodejs package successfully, but still my operating system Ubuntu 15.10 (Wily Werewolf) doesn't recognize the npm command like it is shown below, even though after several update attempts with sudo apt-get update :

user@user-T420:~$ sudo apt-get install nodejs
Reading package lists... Done
Building dependency tree
Reading state information... Done
nodejs is already the newest version.
The following packages were automatically installed and are no longer required:
  authbind diffstat hardening-includes libapt-pkg-perl libarchive-zip-perl
  libbonobo2-0 libbonobo2-common libcamel-1.2-29 libclass-accessor-perl
  libclone-perl libedataserver-1.2-15 libemail-valid-perl libgles1-mesa
  libgnome2-0 libgnome2-bin libgnome2-common libidl-common libidl0
  libindicate5 libio-pty-perl libio-string-perl libipc-run-perl
  libnet-dns-perl libnet-domain-tld-perl libnet-ip-perl liborbit2
  libperlio-gzip-perl libpoppler19 libqt5x11extras5 libsdl-image1.2
  libtext-levenshtein-perl libtiff4 libva-drm1 libxcb-composite0 libxcb-xv0
  linux-headers-4.2.0-16 linux-headers-4.2.0-16-generic
  linux-image-4.2.0-16-generic linux-image-extra-4.2.0-16-generic patchutils
  t1utils vlc-plugin-notify vlc-plugin-samba
Use 'apt-get autoremove' to remove them.
0 upgraded, 0 newly installed, 0 to remove and 3 not upgraded.
user@user-T420:~$ npm -v
The program 'npm' is currently not installed. You can install it by typing:
sudo apt-get install npm

user@user-T420:~$ sudo apt-get install npm
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 npm : Depends: nodejs-dev but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

user@user-T420:~$ sudo apt-get install nodejs-dev
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 nodejs-dev : Depends: libssl-dev (>= 1.0.0g) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

user@user-T420:~$ sudo apt-get install libssl-dev
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 libssl-dev : Depends: libssl1.0.0 (= 1.0.1-4ubuntu5.36) but 1.0.2d-0ubuntu1.4 is to be installed
              Depends: zlib1g-dev but it is not going to be installed
              Recommends: libssl-doc but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

user@user-T420:~$ sudo apt-get install zlib1g-dev
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 zlib1g-dev : Depends: zlib1g (= 1:1.2.3.4.dfsg-3ubuntu4) but 1:1.2.8.dfsg-2ubuntu4 is to be installed
E: Unable to correct problems, you have held broken packages.

It looks an infinite tree of dependencies. Is there a solution to fix it?

If this would be of any help, here's my sources.list file:

#############################################################
############### OFFICIAL UBUNTU REPOSITORIES ################
#############################################################

###### Ubuntu Main Repositories
deb http://us.archive.ubuntu.com/ubuntu/ precise main restricted universe multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ precise main restricted universe multiverse

###### Ubuntu Update Repos
deb http://us.archive.ubuntu.com/ubuntu/ precise-security main restricted universe multiverse
deb http://us.archive.ubuntu.com/ubuntu/ precise-updates main restricted universe multiverse
deb http://us.archive.ubuntu.com/ubuntu/ precise-backports main restricted universe multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ precise-security main restricted universe multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ precise-updates main restricted universe multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ precise-backports main restricted universe multiverse

###### Ubuntu Partner Repository
deb http://archive.canonical.com/ubuntu precise partner
deb-src http://archive.canonical.com/ubuntu precise partner

###### Ubuntu Extras Repository
deb http://extras.ubuntu.com/ubuntu precise main
deb-src http://extras.ubuntu.com/ubuntu precise main

Answer 1

Use aptitude instead of apt-get. It is more intelligent. It not only will handle downgrading conflicting packages for you, but it will make a series of recommendations asking you which of many possible suggested working scenarios you would like.

sudo aptitude install myNewPackage

If you don't have aptitude on your machine yet, get it with

sudo apt-get install aptitude