sys-fstat(2) - Unix First Edition Manual Page
11/3/71SYS_FSTAT (II)

NAME fstat -- get status of open file
SYNOPSIS (file descriptor in r0)sys fstat; buf / fstat = 28.

DESCRIPTION This call is identical to stat, except that it operates onopen files instead of files given by name. It is most

often used to get the status of the standard input andoutput files, whose names are unknown.

SEE_ALSO sys stat
DIAGNOSTICS The error bit (c--bit) is set if the file descriptor isunknown.
OWNER ken, dmr