Search code examples
unixmanpage

Why do programs in Unix-like environments have numbers after their name?

For example, when I run man ioctl the page says IOCTL(2) at the top. What does that mean? Is there an IOCTL(1)? And how does one navigate between these?

Solution

  • It's the man page section. From memory, section 1 is user programs, 2 is system calls, and 3 is standard C library calls, and 5 is file formats.

    Wikipedia has the full explanation here.