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

# mkfontscale

# mkfontdir

# fc-cache

There, the font is installed.

Tip: It is slightly different in different Linux operational systems and you should adjust it.