Linux – Where does the command “top” get its information from in linux

The SHR column simply represents the amount of shared memory used by the process. It can be used for interprocess communications, but a more common scenario is that this is memory used by shared libraries that an application has linked in.

From The Linux Kernel: Memory Management:

Shared Virtual Memory

Although virtual memory allows processes to have separate (virtual) address spaces, there are times when you need processes to share memory. For example there could be several processes in the system running the bash command shell. Rather than have several copies of bash, one in each processes virtual address space, it is better to have only one copy in physical memory and all of the processes running bash share it. Dynamic libraries are another common example of executing code shared between several processes.

Shared memory can also be used as an Inter Process Communication (IPC) mechanism, with two or more processes exchanging information via memory common to all of them. Linux supports the Unix TM System V shared memory IPC.

What the top man page says about this column:

   t: SHR  --  Shared Mem size (kb)
      The amount of shared memory used by a task.  It simply reflects mem‐
      ory that could be potentially shared with other processes.

In bash, detach is a built-in, used as follows:

emacs &
detach %+ # or % + the number in brackets printed after the above

In zsh, you can background and detach in a single operation:

emacs &|