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I was given a "binary" file on linux and a seperate file for windows for a particular task. The programs is an exe on windows. A linux version of the file has the same function on linux as it had windows, too.
However, I've failed to be able to execute this. I tried (on the terminal) to execute it by just the file name, ./[filename], and even tried chmod +x [filename] and then tried the second way.
For everything... I get the result: "Command not found". (The file is definitely there, by the way).
What am I supposed to do? The file command on it yields:
ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux.so.2, for GNU/Linux 2.6.32, BuildID[sha1]=e805f746e65c09cc8b0c037d8a8c27ee0a6a051c
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To use some code from an object file, we need to find it first. As I've leaked above, object files are actually ELF files (the same format as Linux executables and shared libraries) and luckily they're easy to parse on Linux with the help of the standard elf.
you can use readelf and objdump to read parts of an elf file. You can also use 'hexdump filename' to get a hexdump of the contents of a binary file (this is likely only useful if you like reading machine code or you are writing an assembler).
In computing, the Executable and Linkable Format (ELF, formerly named Extensible Linking Format), is a common standard file format for executable files, object code, shared libraries, and core dumps.
My guess is that this is 32 bit compile on a 64 bit system. I cross compiled a small c file into a binary using the -m32 option on gcc. This also needed a few extra packages. The resulting a.out looks like this.
% file a.out
a.out: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux.so.2, for GNU/Linux 2.6.32, BuildID[sha1]=be02470c8337b96e7deaaff323bc53865991c3ab, not stripped
Compare this to a native system binary
% file /bin/ls
/bin/ls: 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]=a0823e17cafbe5b2296346216445566840fdfd88, stripped
Running the a.out shows me this.
% ./a.out
zsh: no such file or directory: ./a.out
The specific "Command not found" message is something, I think, bash prints. I use zsh myself.
To get this to work, you can install the multilib packages. I didn't narrow it down to the exact package but installing gcc-multilib on Debian pulls in everything you need. After installing that, here's what I get.
% ./a.out
3.140523
(the program is supposed to estimate the value of PI).
Note: I actually needed to install gcc-multilib just to compile the file. I then uninstalled the packages to mimic a 64 bit system that doesn't have the 32 bit runtime libraries that the thing needs.
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