The rax2 utility comes with the radare framework and aims to be a minimalistic expression evaluator for the shell. It is useful for making base conversions between floating point values, hexadecimal representations, hexpair strings to ascii, octal to integer. It supports endianness and can be used as a shell if no arguments are given.
This is the help message of rax2, this tool can be used in the command-line or interactively (reading the values from stdin), so it can be used as a multi-base calculator.
Inside r2, the functionality of rax2 is available under the ? command. For example:
[0x00000000]> ? 3+4
As you can see, the numeric expressions can contain mathematical expressions like addition, substraction, .. as well as group operations with parenthesis.
The syntax in which the numbers are represented define the base, for example:
3 : decimal, base 10
0xface : hexadecimal, base 16
0472 : octal, base 8
2M : units, 2 megabytes
...
This is the help message of rax2 -h, which will show you a bunch more syntaxes
$ rax2 -h
Usage: rax2 [options] [expr ...]
=[base] ; rax2 =10 0x46 -> output in base 10
int -> hex ; rax2 10
hex -> int ; rax2 0xa
-int -> hex ; rax2 -77
-hex -> int ; rax2 0xffffffb3
int -> bin ; rax2 b30
int -> ternary ; rax2 t42
bin -> int ; rax2 1010d
ternary -> int ; rax2 1010dt
float -> hex ; rax2 3.33f
hex -> float ; rax2 Fx40551ed8
oct -> hex ; rax2 35o
hex -> oct ; rax2 Ox12 (O is a letter)
bin -> hex ; rax2 1100011b
hex -> bin ; rax2 Bx63
ternary -> hex ; rax2 212t
hex -> ternary ; rax2 Tx23
raw -> hex ; rax2 -S < /binfile
hex -> raw ; rax2 -s 414141
-l ; append newline to output (for -E/-D/-r/..
-a show ascii table ; rax2 -a
-b bin -> str ; rax2 -b 01000101 01110110
-B str -> bin ; rax2 -B hello
-d force integer ; rax2 -d 3 -> 3 instead of 0x3
-e swap endianness ; rax2 -e 0x33
-D base64 decode ;
-E base64 encode ;
-f floating point ; rax2 -f 6.3+2.1
-F stdin slurp code hex ; rax2 -F < shellcode.[c/py/js]
-h help ; rax2 -h
-i dump as C byte array ; rax2 -i < bytes
-k keep base ; rax2 -k 33+3 -> 36
-K randomart ; rax2 -K 0x34 1020304050
-L bin -> hex(bignum) ; rax2 -L 111111111 # 0x1ff
-n binary number ; rax2 -n 0x1234 # 34120000
-N binary number ; rax2 -N 0x1234 # \x34\x12\x00\x00
-r r2 style output ; rax2 -r 0x1234
-s hexstr -> raw ; rax2 -s 43 4a 50
-S raw -> hexstr ; rax2 -S < /bin/ls > ls.hex
-t tstamp -> str ; rax2 -t 1234567890
-x hash string ; rax2 -x linux osx
-u units ; rax2 -u 389289238 # 317.0M
-w signed word ; rax2 -w 16 0xffff
-v version ; rax2 -v
