Go to main content

man pages section 1: User Commands

Exit Print View

Updated: Wednesday, July 27, 2022

ndisasm (1)


ndisasm - the Netwide Disassembler, an 80x86 binary file disassembler


ndisasm [ -o origin ] [ -s sync-point [...]] [ -a | -i ] [ -b bits ] [
-u ] [ -e hdrlen ] [ -p vendor ] [ -k offset,length [...]] infile


The Netwide Assembler Project                                       NDISASM(1)

       ndisasm - the Netwide Disassembler, an 80x86 binary file disassembler

       ndisasm [ -o origin ] [ -s sync-point [...]] [ -a | -i ] [ -b bits ] [
       -u ] [ -e hdrlen ] [ -p vendor ] [ -k offset,length [...]] infile

       The ndisasm command generates a disassembly listing of the binary file
       infile and directs it to stdout.

           Causes ndisasm to exit immediately, after giving a summary of its
           invocation options.

           Causes ndisasm to exit immediately, after displaying its version

       -o origin
           Specifies the notional load address for the file. This option
           causes ndisasm to get the addresses it lists down the left hand
           margin, and the target addresses of PC-relative jumps and calls,

       -s sync-point
           Manually specifies a synchronisation address, such that ndisasm
           will not output any machine instruction which encompasses bytes on
           both sides of the address. Hence the instruction which starts at
           that address will be correctly disassembled.

       -e hdrlen
           Specifies a number of bytes to discard from the beginning of the
           file before starting disassembly. This does not count towards the
           calculation of the disassembly offset: the first disassembled
           instruction will be shown starting at the given load address.

       -k offset,length
           Specifies that length bytes, starting from disassembly offset
           offset, should be skipped over without generating any output. The
           skipped bytes still count towards the calculation of the
           disassembly offset.

           Enables automatic (or intelligent) sync mode, in which ndisasm will
           attempt to guess where synchronisation should be performed, by
           means of examining the target addresses of the relative jumps and
           calls it disassembles.

       -b bits
           Specifies 16-, 32- or 64-bit mode. The default is 16-bit mode.

           Specifies 32-bit mode, more compactly than using `-b 32'.

       -p vendor
           Prefers instructions as defined by vendor in case of a conflict.
           Known vendor names include intel, amd, cyrix, and idt. The default
           is intel.

       ndisasm only disassembles binary files: it has no understanding of the
       header information present in object or executable files. If you want
       to disassemble an object file, you should probably be using objdump(1).

       Auto-sync mode won't necessarily cure all your synchronisation
       problems: a sync marker can only be placed automatically if a jump or
       call instruction is found to refer to it before ndisasm actually
       disassembles that part of the code. Also, if spurious jumps or calls
       result from disassembling non-machine-code data, sync markers may get
       placed in strange places. Feel free to turn auto-sync off and go back
       to doing it manually if necessary.

       See attributes(7) for descriptions of the following attributes:

       |Availability   | developer/nasm        |
       |Stability      | Pass-through volatile |


       Source code for open source software components in Oracle Solaris can
       be found at https://www.oracle.com/downloads/opensource/solaris-source-

       This software was built from source available at
       https://github.com/oracle/solaris-userland.  The original community
       source was downloaded from

       Further information about this software can be found on the open source
       community website at https://www.nasm.us/.

NASM                              08/28/2020                        NDISASM(1)