The article explains the meaning of the numbers found in Linux man page titles, such as sleep(3) or read(2). These numbers indicate the manual section: for example, section 1 covers executable programs, section 2 system calls, and section 3 library calls, with additional suffix letters denoting standards like POSIX or X documentation. The author discovered this detail after a code review clarified the correct section reference for a function’s man page.
https://lalitm.com/til-number-in-man-page-titles-e-g-sleep-3/