On Sat, Apr 16, 2022 at 08:06:23AM +0800, wilson wrote: > > > Greg Wooledge wrote: > > if [ "$1" == on ] > > this sounds strange. why a string doesn't need "" around in shell script?
You only need quotes to force a literal interpretation of whitespace or other special characters, or to suppress word splitting and filename expansion (globbing) after a substitution. Consider a command like this: ls -l .bashrc You've got a command name, and you're passing two string arguments to it. If you feel a need to quote every string argument, then you should be writing it like this: ls "-l" ".bashrc" But nobody does that. It's simply unnecessary. Likewise, you don't need quotes around "on" or "off" because they don't contain special characters. You also don't need quotes around the "==" string argument that was passed in this command. It's funny that you would think you should put quotes around "on" but not around "==", isn't it.
