This is ctypes.sh, a foreign function interface for bash.

ctypes.sh is a bash plugin that provides a foreign function interface directly in your shell. In other words, it allows you to call routines in shared libraries from within bash.

A (very) simple example will help illustrate:

$ dlcall puts "hello, world"
hello, world

# A more complex example, use libm to calculate sin(PI/2)
$ dlopen libm.so.6
0x172ebf0
$ dlcall -r double sin double:1.57079632679489661923
double:1.000000

ctypes.sh can extend bash scripts to accomplish tasks that were previously impossible, or would require external helpers to be written.

ctypes.sh makes it possible to use GTK natively in your shell scripts, or write a high-performance http daemon.

See more examples here

ctypes.sh is dependent on the following libraries and programs:

• libffi
• bash
• libelf (optional)
• elfutils (optional)
• libdwarf / libdw (optional)

For recent Fedora, this should be enough:

sudo yum install elfutils-devel dnf-utils

Now you can use the debuginfo-install command to install debugging symbols for automatic structure support.

For recent Ubuntu, this should be enough:

sudo apt install autoconf libltdl-dev libffi-dev libelf-dev elfutils libdw-dev

If you want to use automatic struct support (recommended), you should also make you have ddebs available.

ctypes.sh can be installed from source like this:

$ git clone https://github.com/taviso/ctypes.sh.git
$ cd ctypes.sh
$ ./autogen.sh
$ ./configure
$ make
$ [sudo] make install

By default ctypes.sh is installed into /usr/local/bin and /usr/local/lib. You can overload the prefix path by defining the PREFIX environment variable before installing.

$ PREFIX=$HOME make install

source ctypes.sh
puts () {
  dlcall puts "$@"
  return $?
}

puts "hello, world"

• "that's disgusting"
• "this has got to stop"
• "you've gone too far with this"
• "is this a joke?"
• "I never knew the c could stand for Cthulhu."

You can read more about ctypes.sh and see it in action on the Wiki