Comparing Bytes

c (short for "compare") allows you to compare arrays of bytes from different sources. The command accepts input in a number of formats, and then compares it against values found at current seek position.

[0x00404888]> c?
|Usage: c[?dfx] [argument]
| c  [string]    Compares a plain with escaped chars string
| cc [at] [(at)] Compares in two hexdump columns of block size
| c4 [value]     Compare a doubleword from a math expression
| c8 [value]     Compare a quadword from a math expression
| cx [hexpair]   Compare hexpair string
| cX [addr]      Like 'cc' but using hexdiff output
| cf [file]      Compare contents of file at current seek
| cg[o] [file]   Graphdiff current file and [file]
| cu [addr] @at  Compare memory hexdumps of $$ and dst in unified diff
| cw[us?] [...]  Compare memory watchers
| cat  [file]    Show contents of file (see pwd, ls)
| cl|cls|clear   Clear screen, (clear0 to goto 0, 0 only)

To compare memory contents at current seek position against given string of values, use cx:

[0x08048000]> p8 4
7f 45 4c 46 

[0x08048000]> cx 7f 45 90 46
Compare 3/4 equal bytes
0x00000002 (byte=03)   90 ' '  ->  4c 'L'
[0x08048000]> 

Another subcommand of c command is cc which stands for "compare code". To compare a byte sequence with a sequence in memory:

[0x4A13B8C0]> cc 0x39e8e089 @ 0x4A13B8C0

To compare contents of two functions specified by their names:

[0x08049A80]> cc sym.main2 @ sym.main

c8 compares a quadword from the current seek (in the example below, 0x00000000) against a math expression:

[0x00000000]> c8 4

Compare 1/8 equal bytes (0%)
0x00000000 (byte=01)   7f ' '  ->  04 ' '
0x00000001 (byte=02)   45 'E'  ->  00 ' '
0x00000002 (byte=03)   4c 'L'  ->  00 ' '

The number parameter can of course also be a math expressions which uses flag names etc:

[0x00000000]> cx 7f469046

Compare 2/4 equal bytes
0x00000001 (byte=02)   45 'E'  ->  46 'F'
0x00000002 (byte=03)   4c 'L'  ->  90 ' '

You can use the compare command to find differences between a current block and a file previously dumped to a disk:

r2 /bin/true
[0x08049A80]> s 0
[0x08048000]> cf /bin/true
Compare 512/512 equal bytes

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