android pid uid tid 的区别
Tid（thead id）
- 可以理解为线程的Id:
- Application中拿到主线程的Tid。android.os.Process.myTid()；
PID:
- 进程id，一个pid对应一个进程，每次杀死进程，再重新启动程序，系统都会赋予一个新的pid，一般情况下一个应用程序对应一个pid，但一个应用程序也可以有多个pid;
Uid
- UID在linux中就是用户的ID，表明时哪个用户运行了这个程序，主要用于权限的管理。而在android 中又有所不同，因为android为单用户系统，这时UID 便被赋予了新的使命，数据共享，为了实现数据共享，android为每个应用几乎都分配了不同的UID，不像传统的linux，每个用户相同就为之分配相同的UID。（当然这也就表明了一个问题，android只能时单用户系统，在设计之初就被他们的工程师给阉割了多用户），使之成了数据共享的工具。
pid = process IDuid = user ID of the application that owns that processgid = group IDs of the application that owns that process
pid: The is the process ID (PID) of the process you call the Process.pid method in.ppid: The PID of the parent process (the process that spawned the current one). For example, if you run ruby test.rb in a bash shell, PPID in that process would be the PID of Bash.uid: The UNIX ID of the user the process is running under.euid: The effective user ID that the process is running under. The EUID determines what a program is allowed to do, based on what the user with this UID is allowed to do. Typically the same as uid, but can be different with commands like sudo.gid: The UNIX group ID the program is running under.egid: Like euid, but for groups.
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