[Fix #776] Support GNU top

modules/utility/init.zsh

@@ -146,8 +146,13 @@ alias du='du -kh'
 if (( $+commands[htop] )); then
   alias top=htop
 else
+  if [[ "$OSTYPE" == darwin*|*bsd* ]]; then
     alias topc='top -o cpu'
     alias topm='top -o vsize'
+  else
+    alias topc='top -o %CPU'
+    alias topm='top -o %MEM'
+  fi
 fi
 
 # Miscellaneous