Display issue with oh-my-zsh agnoster theme

As stated on the agnoster-github-page you need either a

• Powerline-patched font
• Font that contains the characters needed

Your currently used font seems to be missing the \ue0b0 char. It looks different from what it should look like (A full-line-height one-char-wide right pointing triangle)

I would look into some of these fonts:

• Patched fonts for Powerline users
• Being a fan of not using patched fonts I prefer Hack and FiraCode

You just need to install a font that contains these characters. for example, you can install Powerline fonts using this command:

sudo apt-get install fonts-powerline

That worked for me as well.

I was having this issue on Debian 9 with urxvt. Fixed it changing font to Hack. Thanks to @AnimiVulpis answer.

Install Hack font on Debian:

apt-get install fonts-hack-ttf

Configure on ~/.Xresources:

URxvt.font: xft:Hack:size=8