lp_runtime: use more shell builtins
lp_runtime: use more shell builtins

smadhueagle/liquidprompt,laurentbardin/liquidprompt,dtschan/liquidprompt,milouse/liquidprompt,tsbarnes/liquidprompt,joshuarubin/dotfiles,BobHood/liquidprompt,dpilone/liquidprompt,alexprengere/liquidprompt,nojhan/liquidprompt,jaesivsm/liquidprompt,joshuarubin/dotfiles,pkkolos/liquidprompt,dan-cleinmark/liquidprompt,joshuarubin/dotfiles,joshuarubin/dotfiles