$$ 在shell中是什么意思?
我曾经读到过，在 shell 中为临时文件获取唯一文件名的一种方法是使用双美元符号 ($$).这确实会产生一个不时变化的数字……但是如果您重复调用它，它会返回相同的数字.(解决办法就是利用时间.)
I once read that one way to obtain a unique filename in a shell for temp files was to use a double dollar sign ($$). This does produce a number that varies from time to time... but if you call it repeatedly, it returns the same number. (The solution is to just use the time.)
我很想知道 $$ 究竟是什么，以及为什么建议将其作为生成唯一文件名的一种方式.
I am curious to know what $$ actually is, and why it would be suggested as a way to generate unique filenames.
在 Bash 中 $$ 是进程 ID，如注释中所述，将其用作临时文件名是不安全的各种原因.
In Bash $$ is the process ID, as noted in the comments it is not safe to use as a temp filename for a variety of reasons.
对于临时文件名，请使用 mktemp 命令.
For temporary file names, use the mktemp command.