strace
strace is a diagnostic, debugging and instructional userspace utility for Linux. It is used to monitor and tamper with interactions between processes and the Linux kernel, which include system calls, signal deliveries, and changes of process state. The operation of strace is made possible by the kernel feature known as ptrace.
在Linux世界，进程不能直接访问硬件设备，当进程需要访问硬件设备（比如读取磁盘文件，接收网络数据等等）时，必须由用户态模式切换至内核态模式，通过系统调用访问硬件设备。strace可以跟踪到一个进程产生的系统调用，包括参数，返回值，执行消耗的时间。
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