The GNU C Library - Argument Syntax Go to the first , previous , next , last section, table of contents . Multiple options may follow a hyphen delimiter in a single token if the options do not take arguments. Certain options require an argument. An option and its argument may or may not appear as separate tokens.
Options typically precede other non-option arguments.
It does this by reordering the elements of the argv array. See section Standard Environment Variables . A token consisting of a single hyphen character is interpreted as an ordinary non-option argument. By convention, it is used to specify input from or output to the standard input and output streams. Options may be supplied in any order, or appear multiple times.