Below is a list of the most frequently used configuration variables. You can get a complete list by issuing e command without arguments. For example, to see all variables defined in the "cfg" namespace, issue e cfg. (mind the ending dot). You can get help on any eval configuration variable by using ??e cfg.
asm.arch
Defines target CPU architecture used for disassembling (pd, pD commands) and code analysis (a command). You can find the list of possible value by looking at the result of e asm.arch=? or rasm2 -L.
It is quite simple to add new architectures for disassembling and analyzing code. There is an interface for that. For x86, it is used to attach a number of third-party disassembler engines, including GNU binutils, Udis86 and a few of handmade ones.
asm.bits
Determines width in bits of registers for current architecture. Supported values: 8, 16, 32, 64. Note that not all target architectures support all combinations for asm.bits.
asm.syntax
Changes syntax flavor for disassembler between Intel and AT&T. At the moment, this setting affects Udis86 disassembler for Intel 32/Intel 64 targets only. Supported values are intel and att.
asm.pseudo
A boolean value to choose a string disassembly engine. "False" indicates a native one, defined by current architecture, "true" activates a pseudocode strings format; for example, it will show eax=ebx instead of a mov eax, ebx.
asm.os
Selects a target operating system of currently loaded binary. Usually OS is automatically detected by rabin -rI. Yet, asm.os can be used to switch to a different syscall table employed by another OS.
asm.flags
If defined to "true", disasembler view will have flags column.
asm.linescall
If set to "true", draw lines at the left of dissassemble output (pd, pD commands) to graphically represent control flow changes (jumps and calls) that are targeted inside current block. Also, see asm.linesout.
asm.linesout
When defined as "true", the disassembly view will also draw control flow lines that go ouside of the block.
asm.linestyle
A boolean value which changes the direction of control flow analysis. If set to "false", it is done from top to bottom of a block; otherwise, it goes from bottom to top. The "false" setting seems to be a better choice for improved readability, and is the default one.
asm.offset
Boolean value which controls visibility of offsets for individual disasembled instructions.
asm.trace
A boolean value that controls displaying of tracing information (sequence number and counter) at the left of each opcode. It is used to assist programs trace analysis.
asm.bytes
A boolean value used to show or hide displaying of raw bytes of instructions.
cfg.bigendian
Change endianness. "true" means big-endian, "false" is for little-endian.
file.analyze
A boolean value. If set, radare will run .af* @@ sym. and .af* @ entrypoint after resolving the symbols binary loading time. This way, radare will extract maximum of available information from the binary. Note that this configuration item does not affect type of analysis used when opening a project file. This option requires "file.id" and "file.flag" both to be true.
scr.color
This boolean variable enables or disables colorized screen output.
scr.seek
This variable accepts an expression, a pointer (eg. eip), etc. If set, radare will set seek position to its value on startup.
cfg.fortunes
Enables or disables "fortune" messages displayed at each radare start.