c - What is the difference between read and pread in unix?

Question

What is the difference between the functions read() and pread() in unix?
When choosing between them, what points should I take into consideration?

I googled for the difference between them but without results.

question from:https://stackoverflow.com/questions/1687275/what-is-the-difference-between-read-and-pread-in-unix

Answer 1

Pread() works just like read() but reads from the specified position in the file without modifying the file pointer.

You would use it when you need to repeatedly read data at fixed offset, for example a database index that points to individual records in file, to save on seek() calls.

Basically use read() if your data is sequential or pread() if you know, or can calculate offset at which to read.