Linux socket read Data error interpretation

Eintr

Represents a kind of blocking operation, the received signal is interrupted, resulting in an erroneous return value.

Eagain

Literally, it is a hint to try again. This error often occurs when the application is doing some non-blocking (non-blocking) operations (for files or sockets). For example, open the file/socket/fifo with the O_nonblock flag, if you do a sequential read operation and no data is readable. At this point the program does not block up and waits for the data to be ready to return, and the Read function returns an error eagain, prompting your application to now have no data to read please try again later.

Linux socket read Data error interpretation