In Linux OS, Here are ways to install .ttf, .otf, .ttc, .pfa fonts, among which, .pfa fonts need to affiliated with .afm fonts :
A. Desk System
a. Double click the file and click "Install" button.
b. Input "/" key and input "fonts:/" to build a new sub-catalog such as Chinese and drag font file to it.(such as /usr/share/fonts/chinese/)
B. Command Line
Step 1. Build a new sub-catalog under the catalog of /usr/share/fonts and as in:
# mkdir /usr/share/fonts/chinese
Step 2: Copy font file to the sub-catalog such as /root/desktop as in:
# cd /root/desktop
# cp font.ttf /usr/share/fonts/chinese/
Step3: Build index information of Fonts and update font cache, as in:
# cd /usr/share/fonts/chinese
There, the font is installed.
Tip: It is slightly different in different Linux operational systems and you should adjust it.