On MacOS, cb is trying to run xclip

[PenelopeFudd]

Describe the bug
I ran brew install clipboard and when I run cb, it initially said "xclip not installed", and after I installed it with brew install xclip now it says "Error: Can't open display: (null)" for most commands. All I wanted to do was copy html-formatted clipboard contents from a file and paste them into Slack, and vice-versa.

To Reproduce

$ brew install clipboard
$ brew install xclip
$ cb paste
Error: Can't open display: (null)
Copied to clipboard: paste
$ cb info
Error: Can't open display: (null)
Copied to clipboard: info

**Expected behavior**
I'm pretty sure it shouldn't be trying to use xclip.

**Screenshots**
If applicable, add screenshots to help explain your problem.
n/a

**Version**
0.10.0

**Additional context**
n/a

[Slackadays]

I have no idea what could be happening here, as cb doesn't do anything with xclip nor is xclip even useful on macOS. Could it be something with your system, as cb is popular on macs but you're the first to have this issue?

[PenelopeFudd]

$ which cb

/usr/local/bin/cb

$ ls -la /usr/local/bin/cb

lrwxr-xr-x  1 username  admin  33 19 Dec 17:09 /usr/local/bin/cb -> ../Cellar/clipboard/0.10.0/bin/cb

$ cb
 
Copies a string to the clipboard.
Usage: cb <string>
       echo <string> | cb
 
$ echo string | cb
 
Error: Can't open display: (null)
Copied to clipboard: string

I really can't explain it, other than maybe the Brew Recipe for clipboard has an error of some kind that compiles the Xwindow version.