Convert hexadecimal ascii text listings like 303132 to binary with the free sfk for windows and linux, allowing also prefiltering of the input data.

- download the free swiss file knife base from sourceforge.
- unpack the tool using winzip or unzip.
- open the Windows Command Line or a Linux shell.

sfk ... +hextobin outfile

convert lines of text containing hexdump to binary.

chain-only command.

   hextobin can be used only after another command,
   typically filter, which reads and prepares the input data.

examples:

   sfk filter dump.txt +hextobin out.dat
      requires dump.txt to contain pure hex data, e.g.

         7466696C 65732F46 6F726D61 74732F31

      blanks and some chars like <> are skipped automatically.

   sfk filter dump.txt "-+ >" -rep "_<*__" +hextobin out.dat
      takes a verbose hexdump produced by "sfk hexdump":

        >73746669 6C65732F 42617365 4C69622F< stfiles/BaseLib/ 00000020

      using only lines starting with " >" (skipping a possible
      filename line), stripping the ascii and offset infos after "< ",
      extracting and converting pure hex data.

   sfk fromclip +hextobin %TEMP%\tmp1.dat +hexdump
      takes a hex sequence like 22737769 73732066 from clipboard,
      printing its text via a temporary file and hexdump.
 
example: write a list of bytes into a binary file

let's say we want to write the binary data

   0x01 0x02 0x03 0x04 0x05

into a binary file "target.exe" at offset 0x9876,
then this can be achieved by these steps:

sfk echo "01 02 03 04 05" +hextobin tmp1.dat

   writes the byte sequence into a temporary file.

sfk partcopy tmp1.dat 0 5 target.exe 0x9876 -yes

   copies these bytes from tmp1.dat into target.exe,
   which must exist, at the offset 0x9876 (39030 decimal).


   finally, you may

sfk hexdump target.exe -offlen 0x9870 20

   to check the result by dumping the bytes around that area:

    :file target.exe
    >28C80000 10C20102 03040500 00000000< (............... 00009870
    >00000000 06C90000 44C20000 00000000< ........D....... 00009880


see also:

sfk hexdump    - creating hexdumps from binary data.
sfk partcopy   - copy parts of a binary file.

read more about all sfk functions here.