I tried install ImageMagick in Ruby workspace by command:
$ sudo apt-get install imagemagick
I have this response:
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package imagemagick is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
N: Ignoring 'c9.list' in directory '/etc/apt/sources.list.d/' as it is not a regular file
E: Package 'imagemagick' has no installation candidate
What I should to to install Imagemagick correctly?