Configuration
The core reads ~/.radare2rc while starting. You can add e commands to this file to tune radare configuration to your taste.
To prevent radare from parsing this file at start, pass it -n option. To have a less verbose output for batch mode runs, it is also better to decrease verbosity level with -v command-line option.
All the configuration of radare is done with the eval commands. A typical startup configuration file looks like this:
$ cat ~/.radare2rc
e scr.color = true
e dbg.bep   = loader
Configuration can also be changed with -e scr.color and asm.syntax the following line may be used:
$ radare2 -n -e scr.color=true -e asm.syntax=intel -d /bin/ls
Internally, the configuration is stored in a hash table. The variables are grouped in namespaces: cfg., file., dbg., scr. and so on.
To get a list of all configuration variables just type e in the command line prompt. To limit output to a selected namespace, pass it with an ending dot to e. For example, e file. will display all variables defined inside "file" namespace.
To get help about e command type e?:
Usage: e[?] [var[=value]]
e?              show this help
e?asm.bytes     show description
e??             list config vars with description
e               list config vars
e-              reset config vars
e*              dump config vars in r commands
e!a             invert the boolean value of 'a' var
er [key]        set config key as readonly. no way back
ec [k] [color]  set color for given key (prompt, offset, ...)
e a             get value of var 'a'
e a=b           set var 'a' the 'b' value
env [k[=v]]     get/set environment variable
A simpler alternative to e command is accessible from the visual mode. Type Ve to enter it, use arrows (up, down, left, right) to navigate the configuration, and q to exit it. The start screen for the visual cofiguration edit looks like this:
Eval spaces:                                                                   
>  anal                                                                        
   asm                                                                         
   scr                                                                         
   asm                                                                         
   bin                                                                         
   cfg                                                                         
   diff                                                                        
   dir                                                                         
   dbg                                                                         
   cmd                                                                         
   fs                                                                          
   hex                                                                         
   http                                                                        
   graph                                                                       
   hud                                                                         
   scr                                                                         
   search                                                                      
   io