UNIX for Dummies Questions & Answers

The original name is not obscure but well known.

The first "su" implementation was written by Dennis Ritchie and Ken Thompson in 1971. From Unix version 1 to 6, this command meaning and purpose was "become super user".
eg: http://minnie.tuhs.org/cgi-bin/utree...source/s2/su.c

Code:

/* su -- become super-user */

char    password[100];
char    pwbuf[100];
int    ttybuf[3];
main()
{

Its manual page stated:

Code:

NAME        su -- become privileged user
SYNOPSIS    su password
DESCRIPTION su allows one to become the super-user, who has
            all sorts of marvelous powers.

However, in version 7, the su command evolved to allow any account to be passed as an option. "su" started then to mean "substitute user".
Version 7 su manual page states

Code:

NAME
       su  -  substitute user id temporarily

SYNOPSIS
       su [ userid ]

"switch user" appeared only later, mostly in Gnu documents or source code, as a synonym of "substitute user.

How wrong could I be? The primary definition in HP-UX man su is switch user with subdefinitions set user and superuser .

I was reading the default man su page from unix.com at the time.