format elf executable 3
entry start
 
section '.text' readable executable
 
start:
mov ebx, 0
mov eax, 1
int 0x80    

flat assembler version 1.70.03 (16384 kilobytes memory)
exit.asm[4]: section '.text' readable executable
error: illegal instruction.

segment mySegment readable executable

To create executable file, follow the format choice directive with the executable keyword and optionally the number specifying the brand of the target operating system (for example value 3 would mark the executable for Linux systems). With this format selected it is allowed to use entry directive followed by the value to set as entry point of program. On the other hand it makes extrn and public directives unavailable, and instead of section there should be the segment directive used, followed by one or more segment permission flags and optionally a marker of special ELF executable segment, which can be interpreter, dynamic or note. The origin of segment is aligned to page (4096 bytes), and available permission flags are: readable, writeable and executable.