If you're willing assume a Linux platform and a Python installation, you can do something like:

  echo -n "base64encodedelf" | base64 --decode | python3 -c 'import os;import sys;f=os.memfd_create(os.MFD_CLOEXEC);os.write(f,sys.stdin.buffer.read());os.execve(f,["dummy"],[])'

Surprising that no combination of bash symbols lets you do this.

Neat. But is the base64 even necessary?

I don’t know that every editor today will gracefully handle a blob that isn’t valid UTF-8. Emacs needed a library (so-long) to disable some features that choke trying to render very long lines.

You'll to edit the shell script without the binary at the end and once you're done you append the blob.

Yes. You can load the decompressed code into memory, mprotect() it to give it execution permissions, then jump in. Hard to do in a shell, though.

Basically everything in Linux will create a temp file one way or another even pipes. For you to take a binary and run it directly it has to have an inode. At best you can use Python & the ctypes module to write a program into part of Python's memory and trick it into continuing execution from there.

Pipes are not temp files, they’re more like kernel buffers associated with no file. When I think of temp file, I think of something that is at least associated with a filesystem.

The reason that running a binary needs a file is because execve() takes a path as an argument. But, as you said, there are other ways to load code into memory.

> Basically everything in Linux will create a temp file one way or another even pipes.

pipe(2) doesn't create a file, at least not in the sense that I usually think about files (something that's accessible through the filesystem).