This concerns incorrect or faulty installation instructions for both Ubuntu and Fedora.
OS: Fedora 29
The installation instruction:
$ sudo dnf install dnf-utils
$ sed 's/%{npm-version:.*}/0/' tools/cockpit.spec | sudo dnf builddep --spec /dev/stdin
Doesn't build correctly because the dependencies somehow don't get installed (the install is aborted because of some error with the pipe). The following does work though:
$ sed 's/%{npm-version:.*}/0/' tools/cockpit.spec > tools/myspec.spec
$ sudo dnf builddep --spec tools/myspec.spec
OS: Ubuntu 18.04.2 LTS,
When following the build from source guide located here, the build step with autogen will fail because of a dependency removal cycle on Ubuntu. The clash is between npm and libssh.
The step:
sudo apt-get install nodejs npm
Installs npm. Then the step:
$ ./autogen.sh --prefix=/usr --enable-debug
Will eventually tell you (see the output of the build script here):
No package 'libssh' found
If you try to install libssh-dev, it will uninstall npm though:
The following packages will be REMOVED:
libssl1.0-dev node-gyp nodejs-dev npm
In fact, this answer on unix.stackexchange explains that they cannot coexist.