od(1)
od [opts] <file>
-An don't print addr info
-tx4 print hex in 4 byte chunks
-ta print as named character
-tc printable chars or backslash escape
-w4 print 4 bytes per line
-j <n> skip <n> bytes from <file> (hex if start with 0x)
-N <n> dump <n> bytes (hex of start with 0x)
ASCII to hex string
echo -n AAAABBBB | od -An -w4 -tx4
>> 41414141
>> 42424242
echo -n '\x7fELF\n' | od -tx1 -ta -tc
>> 0000000 7f 45 4c 46 0a # tx1
>> del E L F nl # ta
>> 177 E L F \n # tc
Extract parts of file
For example .rodata
section from an elf file. We can use readelf
to get the
offset into the file where the .rodata
section starts.
readelf -W -S foo
>> Section Headers:
>> [Nr] Name Type Address Off Size ES Flg Lk Inf Al
>> ...
>> [15] .rodata PROGBITS 00000000004009c0 0009c0 000030 00 A 0 0 16
With the offset of -j 0x0009c0
we can dump -N 0x30
bytes from the beginning of
the .rodata
section as follows:
od -j 0x0009c0 -N 0x30 -tx4 -w4 foo
>> 0004700 00020001
>> 0004704 00000000
>> *
>> 0004740 00000001
>> 0004744 00000002
>> 0004750 00000003
>> 0004754 00000004
Note: Numbers starting with 0x
will be interpreted as hex by od
.