$!
–
PID of Most Recent Background Command
$! expands to the process ID of the most recent background command executed in the current shell.
Links
BashSupport Pro 是一款 Bash 和 POSIX 集成开发环境，支持 $! - 立即试用！
$!
–
PID of Most Recent Background Command$! expands to the process ID of the most recent background command executed in the current shell.