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When I run one of my user's applications named "myfile". 

$ ./myfile

I receive the following output

bash: ./myfile: cannot execute binary file

My user expects the binary file to run. I assume this is a compilation error but am unable to confirm it. I ran the file command

$ file myfile myfile: ELF 64-bit LSB relocatable, x86-64, version 1 (SYSV), not stripped

My RHEL6 OS is 64-bit

$ uname -p -o x86_64 GNU/Linux

So it looks to me like it was complied for the right architecture. I don't understand what "relocatable" means in the file command's output and was not able to get an explanation form the man pages.

For good measure I checked for Shared Library Dependencies

$ ldd myfile not a dynamic executable

Is there any way I can get this file to run or give my user some constructive information about why it won't run (such as he needs to recompile using x)?

Strace

$ strace ./myfile execve("./myfile", ["./myfile"], [/* 22 vars */]) = -1 ENOEXEC (Exec format error) dup(2) = 3 fcntl(3, F_GETFL) = 0x8002 (flags O_RDWR|O_LARGEFILE) fstat(3, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 0), ...}) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f7a9fc93000 lseek(3, 0, SEEK_CUR) = -1 ESPIPE (Illegal seek) write(3, "strace: exec: Exec format error\n", 32strace: exec: Exec format error ) = 32 close(3) = 0 munmap(0x7f7a9fc93000, 4096) = 0 exit_group(1) = ?

readelf output

readelf -S ./myfile There are 13 section headers, starting at offset 0x1e8: Section Headers: [Nr] Name Type Address Offset Size EntSize Flags Link Info Align [ 0] NULL 0000000000000000 00000000 0000000000000000 0000000000000000 0 0 0 [ 1] .text PROGBITS 0000000000000000 00000040 0000000000000098 0000000000000000 AX 0 0 4 [ 2] .rela.text RELA 0000000000000000 000006e0 0000000000000120 0000000000000018 11 1 8 [ 3] .data PROGBITS 0000000000000000 000000d8 0000000000000010 0000000000000000 WA 0 0 4 [ 4] .bss NOBITS 0000000000000000 000000e8 0000000000000000 0000000000000000 WA 0 0 4 [ 5] .rodata PROGBITS 0000000000000000 000000e8 0000000000000033 0000000000000000 A 0 0 1 [ 6] .comment PROGBITS 0000000000000000 0000011b 000000000000002d 0000000000000001 MS 0 0 1 [ 7] .note.GNU-stack PROGBITS 0000000000000000 00000148 0000000000000000 0000000000000000 0 0 1 [ 8] .eh_frame PROGBITS 0000000000000000 00000148 0000000000000038 0000000000000000 A 0 0 8 [ 9] .rela.eh_frame RELA 0000000000000000 00000800 0000000000000018 0000000000000018 11 8 8 [10] .shstrtab STRTAB 0000000000000000 00000180 0000000000000061 0000000000000000 0 0 1 [11] .symtab SYMTAB 0000000000000000 00000528 0000000000000180 0000000000000018 12 9 8 [12] .strtab STRTAB 0000000000000000 000006a8 0000000000000037 0000000000000000 0 0 1 Key to Flags: W (write), A (alloc), X (execute), M (merge), S (strings) I (info), L (link order), G (group), x (unknown) O (extra OS processing required) o (OS specific), p (processor specific)
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  • If you have strace installed, try running it as strace ./myfile. The last few lines should give some indication of the underlying problem. Also, make sure the file isn't located on a volume that is mounted with the noexec flag. Commented Oct 22, 2015 at 16:58
  • @JamesSneeringer Thanks I added the Strace output. Commented Oct 22, 2015 at 17:09
  • It looks to be missing its interpreter. What happens if you run it like /lib64/ld-linux-x86-64.so.2 ./executable? Commented Oct 22, 2015 at 18:10
  • @MatthewIfe The file isn't a shared library executable. The resulting error of the command you suggested is "only ET_DYN and ET_EXEC can be loaded" This provides further evidence that this file is not an executable file. Commented Oct 22, 2015 at 18:44
  • Please provide the output of readelf -S ./executable Commented Oct 22, 2015 at 18:53

1 Answer 1

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13

It sounds like relocatable has to do with an object file that is not an executable.

Executables should look like this

 ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 2.6.32, BuildID[sha1]=a8ff57737fe60fba639d91d603253f4cdc6eb9f7, stripped

Object files look like this

 # file /usr/lib/x86_64-linux-gnu/crtn.o /usr/lib/x86_64-linux-gnu/crtn.o: ELF 64-bit LSB relocatable, x86-64, version 1 (SYSV), not stripped

If needed, you can also get more information this way

# objdump -x myfile

Or disassemble

# objdump -d myfile

List symbols from a object file (not stripped)

 # nm /usr/lib/x86_64-linux-gnu/gcrt1.o U atexit 0000000000000000 b called.4237 0000000000000000 D __data_start 0000000000000000 W data_start U etext 0000000000000030 T __gmon_start__ 0000000000000000 R _IO_stdin_used U __libc_csu_fini U __libc_csu_init U __libc_start_main U main U _mcleanup U __monstartup 0000000000000000 T _start

Trying to list symbols from executable (stripped)

 # nm /bin/bash nm: /bin/bash: no symbols
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  • Am I jumping to conclusions by saying anytime relocatable is in the file output the file is an Object file and not an executable file? Commented Oct 22, 2015 at 17:23
  • Maybe :). I'm going by what people on google say and by what files on my system report. Commented Oct 22, 2015 at 17:24
  • Relevant Ubuntu forums thread. I agree with Ryan, myfile appears to be an object file and not an executable, and just lacks the usual .o extension. Your user may simply have inadvertently compiled their program as an object (e.g. using -c with gcc when they shouldn't have). Commented Oct 22, 2015 at 18:34

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