status: show signal name

This makes signal exit status easy to understand.  Instead of just
showing exit code "137", you now see "KILL(-9)".

Based on #580 by @sei40kr (thanks!)

README.md

@@ -508,6 +508,7 @@ This segment shows the return code of the last command.
 |`POWERLEVEL9K_STATUS_CROSS`|`false`|Set to true if you wish not to show the error code when the last command returned an error and optionally hide this segment when the last command completed successfully by setting `POWERLEVEL9K_STATUS_OK` to false.|
 |`POWERLEVEL9K_STATUS_OK`|`true`|Set to true if you wish to show this segment when the last command completed successfully, false to hide it.|
 |`POWERLEVEL9K_STATUS_SHOW_PIPESTATUS`|`true`|Set to true if you wish to show the exit status for all piped commands.|
+|`POWERLEVEL9K_STATUS_HIDE_SIGNAME`|`false`|Set to true return the raw exit code (`1-255`).  When set to true, values over 128 are shown as `SIGNAME(-n)` (e.g. `KILL(-9)`)|
 
 ##### ram
 

powerlevel9k.zsh-theme

@@ -1086,31 +1086,47 @@ prompt_ssh() {
   fi
 }
 
-# old options, retro compatibility
-set_default POWERLEVEL9K_STATUS_VERBOSE true
-set_default POWERLEVEL9K_STATUS_OK_IN_NON_VERBOSE false
 # Status: When an error occur, return the error code, or a cross icon if option is set
 # Display an ok icon when no error occur, or hide the segment if option is set to false
+#
 set_default POWERLEVEL9K_STATUS_CROSS false
 set_default POWERLEVEL9K_STATUS_OK true
 set_default POWERLEVEL9K_STATUS_SHOW_PIPESTATUS true
+set_default POWERLEVEL9K_STATUS_HIDE_SIGNAME false
+# old options, retro compatibility
+set_default POWERLEVEL9K_STATUS_VERBOSE true
+set_default POWERLEVEL9K_STATUS_OK_IN_NON_VERBOSE false
+
+exit_code_or_status() {
+  local ec=$1
+  if [[ "$POWERLEVEL9K_STATUS_HIDE_SIGNAME" = true ]]; then
+    echo "$ec"
+  elif (( ec <= 128 )); then
+    echo "$ec"
+  else
+    local sig=$(( ec - 128 ))
+    local idx=$(( sig + 1 ))
+    echo "${signals[$idx]}(-${sig})"
+  fi
+}
+
 prompt_status() {
   local ec_text
   local ec_sum
   local ec
 
   if [[ $POWERLEVEL9K_STATUS_SHOW_PIPESTATUS == true ]]; then
-    ec_text=${RETVALS[1]}
+    ec_text=$(exit_code_or_status "${RETVALS[1]}")
     ec_sum=${RETVALS[1]}
 
     for ec in "${(@)RETVALS[2,-1]}"; do
-      ec_text="${ec_text}|${ec}"
+      ec_text="${ec_text}|$(exit_code_or_status "$ec")"
       ec_sum=$(( $ec_sum + $ec ))
     done
   else
     # We use RETVAL instead of the right-most RETVALS item because
     # PIPE_FAIL may be set.
-    ec_text=${RETVAL}
+    ec_text=$(exit_code_or_status "${RETVAL}")
     ec_sum=${RETVAL}
   fi