– 告诉cat不要尝试解析它后面的命令行选项.
例如,如果变量$PIDFILE被定义为PIDFILE =“ – version”,请考虑在两种情况下会发生什么.在我的机器上,它们给出以下结果：
$cat $PIDFILE cat (GNU coreutils) 6.10 Copyright (C) 2008 Free Software Foundation,Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY,to the extent permitted by law. Written by Torbjorn Granlund and Richard M. Stallman. $cat -- $PIDFILE cat: --version: No such file or directory
