mosh can't show "\u2699"

[timfeirg]

The character "\u2699" looks like this: ⚙, a symbol used to indicate the existence of a background job in my favourite zsh theme agnoster, which in local terminal, should looks like this:

$ echo "\u2699"

And nothing shows up at mosh terminal.

[keithw]

Mosh is just using your system's libc (and the current locale) to determine whether a character is printable or not. GNU libc has this character, but OS X does not have as recent a version of Unicode. You can check with this program: http://web.mit.edu/keithw/Public/wcwidthtest.c

With glibc (on Linux), and filling in int val = 0x2699; where it says /* Fill in Unicode scalar value here */, this prints:

UCS version supported is 201103
wcwidth(U+2699) = 1

and Mosh does display the character properly.

See also #478

We have some general plans to fix this in the future by shipping our own Unicode tables (or deriving them from the client's terminal), but for now your best bet may be to file a radar bug with Apple and ask them to update.