How do I install 'convert' on a linux system?
convert is part of the package ImageMagick; try
sudo yum install ImageMagick (or other privilege escalation method as appropriate to your system).
Next time you need a command like this you can figure out what package to install by running something like
yum whatprovides '*/convert'.
To install convert try package manager. Convert is part of ImageMagick package, convert is one of utilities.
Under Debian is possible use
sudo dpkg --install imagemagick
sudo apt-get install imagemagick
It is about 419 MB of space.