Linux, $ () {$} and the difference (rpm)

Article from https://blog.csdn.net/hxchuangxiaochuan/article/details/81204084

$ () Is put in order, `` equivalent, e.g. todaydate = $ (date +% Y% m% d) means executing date, returns the execution result to the variable todaydate, it may be written as todaydate = `date + % Y% m% d`;

$ {Variable} is put in, for example, echo PATH $ {} takes the value of the PATH variable and print, it may not be such as $ PATH brackets.