It's been While since i'm using dash(-) in unix command. But have never found out what exactly is this.Have searched at some place it says . It mean stdin/stdout when used in end of command or like  echo hello > - .For example When i write grep -i it checks with ignore case. (so i think it get argument here as -i)While if sometime when filename or folder name begins with -folderName i need to run rm -f -- -folderName What exactly this dash is can someone explain it in simple term.
What is Dash(-) actually in unix or linux?
linux;dash