Hands-On System Programming with C++

Learning about the tail file example

In this example, we will create a simple program to tail a file. The goal of this example is to mimic the behavior of tail -f -n0, which outputs new additions to a file. The -f argument tells the tail to follow the file and -n0 tells tail to only output to stdout new additions.

The first step is to define the mode we plan to use when opening the file we are tailing, as follows:

constexpr auto mode = std::ios::in | std::ios::ate;

In this case, we will open the file as read-only, and move the read pointer to the end of the file on open.

The next step is to create a tail function that watches for changes to a file and outputs the changes to stdout, as follows:

[[noreturn]] voidtail(std::fstream &file){ while ...