r2 -H to list all the environment variables that matter to know where it will
be looking for files. Those paths depend on the way (and operating system) you have
built r2 for.
R2_PREFIX=/usr MAGICPATH=/usr/share/radare2/2.8.0-git/magic PREFIX=/usr INCDIR=/usr/include/libr LIBDIR=/usr/lib64 LIBEXT=so RCONFIGHOME=/home/user/.config/radare2 RDATAHOME=/home/user/.local/share/radare2 RCACHEHOME=/home/user/.cache/radare2 LIBR_PLUGINS=/usr/lib/radare2/2.8.0-git USER_PLUGINS=/home/user/.local/share/radare2/plugins USER_ZIGNS=/home/user/.local/share/radare2/zigns
RC files are r2 scripts that are loaded at startup time. Those files must be in 3 different places:
radare2 will first try to load /usr/share/radare2/radare2rc
Each user in the system can have its own r2 scripts to run on startup to select the color scheme, and other custom options by having r2 commands in there.
If you want to run a script everytime you open a file, just create a file with the same name of the file
.r2 to it.