r2: Block Size

The block size determines how many bytes Radare commands will process. All commands will work with this constraint. You can temporally change the block size by specifying a numeric argument to the print commands. For example px 20.

[0xB7F9D810]> b?
Usage: b[f] [arg]
b         display current block size
b+3       increase blocksize by 3
b-16      decrement blocksize by 16
b 33      set block size to 33
b eip+4   numeric argument can be an expression
bf foo    set block size to flag size
bm 1M     set max block size

The b command is used to change the block size:

[0x00000000]> b 0x100   ; block size = 0x100
[0x00000000]> b +16     ;  ... = 0x110
[0x00000000]> b -32     ;  ... = 0xf0

The bf command is used to change the block size to value specified by a flag. For example, in symbols, the block size of the flag represents the size of the function.

[0x00000000]> bf sym.main    ; block size = sizeof(sym.main)
[0x00000000]> pd @ sym.main  ; disassemble sym.main
...

You can combine two operations in a single one (pdf):

 [0x00000000]> pdf @ sym.main