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.
$ rax2 -h
Usage: rax2 [options] [expr ...]
int -> hex ; rax2 10
hex -> int ; rax2 0xa
-int -> hex ; rax2 -77
-hex -> int ; rax2 0xffffffb3
int -> bin ; rax2 b30
bin -> int ; rax2 1010d
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
raw -> hex ; rax2 -S < /binfile
hex -> raw ; rax2 -s 414141
-b binstr -> bin ; rax2 -b 01000101 01110110
-B keep base ; rax2 -B 33+3 -> 36
-d force integer ; rax2 -d 3 -> 3 instead of 0x3
-e swap endianness ; rax2 -e 0x33
-f floating point ; rax2 -f 6.3+2.1
-h help ; rax2 -h
-k randomart ; rax2 -k 0x34 1020304050
-n binary number ; rax2 -e 0x1234 # 34120000
-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
-v version ; rax2 -V
Some examples:
$ rax2 3+0x80
0x83
$ rax2 0x80+3
131
$ echo 0x80+3 | rax2
131
$ rax2 -s 4142
AB
$ rax2 -S AB
4142
$ rax2 -S < bin.foo
...
$ rax2 -e 33
0x21000000
$ rax2 -e 0x21000000
33
$ rax2 -k 90203010
+--[0x10302090]---+
|Eo. . |
| . . . . |
| o |
| . |
| S |
| |
| |
| |
| |
+-----------------+