Email checker for mail indexed with mu (matryer#905)

* Email checker for mail indexed with mu

* Use bash instead of sh

* Include image url and update documentation

* Address shellcheck errors

* Tidy up by storing parts of mu commands in variables

* Conditional to display information only when unread mails > 0

* Store results of parenthetical statements instead of results of echo

I was getting the wrong value for unread_total due to how wc -l was
evaluating its input.  This captures the correct value.

Author: andrewsanchez

Email/mu-email-checker.sh

@@ -0,0 +1,39 @@
+#!/bin/bash
+
+# <bitbar.title>Mu Email Checker</bitbar.title>
+# <bitbar.version>v1.0.1</bitbar.version>
+# <bitbar.author>Andrew Sanchez</bitbar.author>
+# <bitbar.author.github>andrewsanchez</bitbar.author.github>
+# <bitbar.desc>Displays results of basic mu find commands</bitbar.desc>
+# <bitbar.image>http://i67.tinypic.com/104pa1w.png</bitbar.image>
+
+# Count total number of emails in inbox, unread mail and drafts indexed with mu
+# Also includes the output for unread emails in the drop down menu
+# Based on a blog post by Ben Maughan at the excellent pragmaticemacs.com
+# http://pragmaticemacs.com/emacs/an-unobtrusive-email-monitor-for-mu4e-on-the-mac/
+# See related post to include mails in outbox using postfix
+# http://pragmaticemacs.com/emacs/using-postfix-instead-of-smtpmail-to-send-email-in-mu4e/
+
+mu="/usr/local/bin/mu"
+
+# mu find patterns
+pinbox="maildir:/INBOX"
+punread="$pinbox AND flag:unread"
+pdrafts="maildir:/drafts"
+
+# Total mail in inbox
+total="$("$mu" find "$pinbox" | wc -l)"
+
+# Unread mails in inbox
+unread="$("$mu" find "$punread" 2> /dev/null)"
+unread_total="$("$mu" find "$punread" 2> /dev/null | wc -l)"
+
+# Drafts
+drafts="$("$mu" find "$pdrafts" | wc -l)"
+
+if [ "$unread_total" -gt 0 ]
+then
+    printf "📪 %i/%i/%i\n" "$unread_total" "$total" "$drafts"
+    echo ---
+    echo "$unread"
+fi