.SH NAME
authbind \- bind sockets to privileged ports without root
.SH SYNOPSIS
-.BI authbind " program"
-.RI [ argument " ...]"
+.BR authbind
+.RI [ options "] " program " [" argument " ...]"
.SH DESCRIPTION
.B authbind
allows a program which does not or should not run as root to bind to
which will allow the program (including any subprocesses it may run)
to bind to low-numbered (<512) ports if the system is configured to
allow this.
+.SH OPTIONS
+.TP
+.B --deep
+Normally,
+.B authbind
+arranges for only the program which it directly invokes to be affected
+by its special version of
+.BR bind (2).
+If you specify
+.B --deep
+then all programs which that program invokes directly or indirectly
+will be affected, so long as they do not unset the environment
+variables set up by
+.BR authbind .
+.TP
+.BI --depth " levels"
+Causes
+.B authbind
+to affect programs which are
+.I levels
+deep in the calling graph. The default is
+.BR "--depth 1" .
.SH ACCESS CONTROL
Access to low numbered ports is controlled by permissions and contents
of files in a configuration area,
.B authbind
to use its value as the path to the shared library to put in
.BR LD_PRELOAD ,
-instead of the compiled-in value.
+instead of the compiled-in value. In any case, unless
+.B --deep
+was specified,
+.B authbind
+will set this variable to the name of the library actually added to
+.BR LD_PRELOAD ,
+so that the library can find and remove the right entry.
.TP
-.I AUTHBIND_NESTED
-Do not set this variable. It is set to
-.B 1
-by
-.B libauthbind
-when it invokes the helper program. This allows detection of the
-situation where the helper has not been installed setuid, which would
-otherwise lead to infinite recursion.
+.I AUTHBIND_LEVELS
+This variable is set by
+.B authbind
+to the number of levels left from the
+.B --depth
+or
+.B --deep
+option, minus one. It is decremented during
+.B _init
+by the library on each program call, and the library will remove
+itself from the
+.B LD_PRELOAD
+when it reaches zero. The special value
+.B y
+means
+.B --deep
+was specified.
.SH SEE ALSO
.BR bind (2),
.BR authbind\-helper (8),