单字符的单破折号`-`,单词的双破折号`--`?
字母中使用单破折号和单词使用双破折号的惯例从何而来?为什么继续使用? 例如,如果输入ls --help,您将看到: -a, --all do not ignore entries starting with . -A, --almost-all do not list implied . and .. --author with -l, print the author of each file -b, --escape print octal escapes for nongraphic characters --block-size=SIZE use SIZE-byte blocks -B, --ignore-backups do not list implied entries ending …