bash “$$”在shell脚本中是什么意思？
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What does "$$" means in shell script?
提问by vinit dhatrak
I came across "$$" expression in shell script, something like this
我在 shell 脚本中遇到了 "$$" 表达式，类似这样
TFILE=$$
TFILE=$$
Can anyone tell me its meaning?
谁能告诉我它的意思？
回答by Ether
$$means the process ID of the currently-running process.
$$表示当前正在运行的进程的进程 ID。
回答by teapot7
It's the process id of the current process - see a previous question on StackOverflow for details: What does $$ mean in the shell?
它是当前进程的进程 id - 有关详细信息，请参阅 StackOverflow 上的上一个问题：$$ 在 shell 中意味着什么？
回答by Venkataramesh Kommoju
$$ is the process id of the currently running process in UNIX.
$$ 是 UNIX 中当前正在运行的进程的进程 ID。
mostly it is used with naming of logfiles aor temp files, such that there is no conflict of file names while multiple instances of the same scripts are running.
大多数情况下，它与日志文件或临时文件的命名一起使用，以便在运行相同脚本的多个实例时不会出现文件名冲突。
回答by Ashitosh
echo "$$" prints PID of current running process.
echo "$$" 打印当前正在运行的进程的 PID。
