When I type man regex
into a shell, this loads
REGEX(3) Linux Programmer's Manual REGEX(3)
NAME
regcomp, regexec, regerror, regfree - POSIX regex functions
SYNOPSIS
........
when I type man 7 regex
I get a different man page
REGEX(7) Linux Programmer's Manual REGEX(7)
NAME
regex - POSIX.2 regular expressions
DESCRIPTION
........
What is happening here?