diff --git a/configure.in b/configure.in
index 64dfacc..3ce89d4 100644
--- a/configure.in
+++ b/configure.in
@@ -283,6 +283,12 @@ AC_INIT(c/scheme48vm.c)
     EXEEXT=".exe"
   ;;
   
+  ## The GNU Hurd
+  *-*-gnu* )
+  machine=gnu
+  SCSH_ELF
+  ;;
+
   ## Generic Configuration
   * )
   machine=generic
diff --git a/scsh/gnu/Makefile.inc b/scsh/gnu/Makefile.inc
new file mode 100644
index 0000000..ce9a878
--- /dev/null
+++ b/scsh/gnu/Makefile.inc
@@ -0,0 +1 @@
+# Make `diff' happy.
diff --git a/scsh/gnu/bufpol.scm b/scsh/gnu/bufpol.scm
new file mode 100644
index 0000000..d314b8a
--- /dev/null
+++ b/scsh/gnu/bufpol.scm
@@ -0,0 +1,13 @@
+;;; Flags that control buffering policy.
+;;; Copyright (c) 1993 by Olin Shivers. See file COPYING.
+;;; Copyright (c) 1995 by Brian D. Carlstrom.
+
+;;; These are for the SET-PORT-BUFFERING procedure, essentially a Scheme
+;;; analog of the setbuf(3S) stdio call. We use the actual stdio values.
+;;; These constants are not likely to change from stdio lib to stdio lib,
+;;; but you need to check when you do a port.
+
+(define-enum-constants bufpol
+  (block	0)	; _IOFBF
+  (line		1)	; _IOLBF
+  (none		2))	; _IONBF
diff --git a/scsh/gnu/errno.scm b/scsh/gnu/errno.scm
new file mode 100644
index 0000000..6a55adb
--- /dev/null
+++ b/scsh/gnu/errno.scm
@@ -0,0 +1,110 @@
+;;; Errno constant definitions.
+;;; Copyright (c) 1993 by Olin Shivers. See file COPYING.
+
+;;; These are the correct values for the GNU Hurd.
+
+(define (hurd-errno n)
+  (bitwise-ior (arithmetic-shift #x10 26) (bitwise-and n #x3fff)))
+
+(define errno/perm (hurd-errno 1))		; Operation not permitted
+(define errno/noent (hurd-errno 2))		; No such file or directory
+(define errno/srch (hurd-errno 3))		; No such process
+(define errno/intr (hurd-errno 4))		; Interrupted system call
+(define errno/io (hurd-errno 5))		; Input/output error
+(define errno/nxio (hurd-errno 6))		; No such device or address
+(define errno/2big (hurd-errno 7))		; Argument list too long
+(define errno/noexec (hurd-errno 8))		; Exec format error
+(define errno/badf (hurd-errno 9))		; Bad file descriptor
+(define errno/child (hurd-errno 10))		; No child processes
+(define errno/deadlk (hurd-errno 11))		; Resource deadlock avoided
+(define errno/nomem (hurd-errno 12))		; Cannot allocate memory
+(define errno/acces (hurd-errno 13))		; Permission denied
+(define errno/fault (hurd-errno 14))		; Bad address
+(define errno/notblk (hurd-errno 15))		; Block device required
+(define errno/busy (hurd-errno 16))		; Device or resource busy
+(define errno/exist (hurd-errno 17))		; File exists
+(define errno/xdev (hurd-errno 18))		; Invalid cross-device link
+(define errno/nodev (hurd-errno 19))		; No such device
+(define errno/notdir (hurd-errno 20))		; Not a directory
+(define errno/isdir (hurd-errno 21))		; Is a directory
+(define errno/inval (hurd-errno 22))		; Invalid argument
+(define errno/nfile (hurd-errno 23))		; Too many open files in system
+(define errno/mfile (hurd-errno 24))		; Too many open files
+(define errno/notty (hurd-errno 25))		; Inappropriate ioctl for device
+(define errno/txtbsy (hurd-errno 26))		; Text file busy
+(define errno/fbig (hurd-errno 27))		; File too large
+(define errno/nospc (hurd-errno 28))		; No space left on device
+(define errno/spipe (hurd-errno 29))		; Illegal seek
+(define errno/rofs (hurd-errno 30))		; Read-only file system
+(define errno/mlink (hurd-errno 31))		; Too many links
+(define errno/pipe (hurd-errno 32))		; Broken pipe
+(define errno/dom (hurd-errno 33))		; Numerical argument out of domain
+(define errno/range (hurd-errno 34))		; Numerical result out of range
+(define errno/again (hurd-errno 35))		; Resource temporarily unavailable
+(define errno/wouldblock (hurd-errno 35))	; Operation would block
+(define errno/inprogress (hurd-errno 36))	; Operation now in progress
+(define errno/already (hurd-errno 37))		; Operation already in progress
+(define errno/notsock (hurd-errno 38))		; Socket operation on non-socket
+(define errno/destaddrreq (hurd-errno 39))	; Destination address required
+(define errno/msgsize (hurd-errno 40))		; Message too long
+(define errno/prototype (hurd-errno 41))	; Protocol wrong type for socket
+(define errno/noprotoopt (hurd-errno 42))	; Protocol not available
+(define errno/protonosupport (hurd-errno 43))	; Protocol not supported
+(define errno/socktnosupport (hurd-errno 44))	; Socket type not supported
+(define errno/opnotsupp (hurd-errno 45))	; Operation not supported
+(define errno/pfnosupport (hurd-errno 46))	; Protocol family not supported
+(define errno/afnosupport (hurd-errno 47))	; Address family not supported by protocol
+(define errno/addrinuse (hurd-errno 48))	; Address already in use
+(define errno/addrnotavail (hurd-errno 49))	; Cannot assign requested address
+(define errno/netdown (hurd-errno 50))		; Network is down
+(define errno/netunreach (hurd-errno 51))	; Network is unreachable
+(define errno/netreset (hurd-errno 52))		; Network dropped connection on reset
+(define errno/connaborted (hurd-errno 53))	; Software caused connection abort
+(define errno/connreset (hurd-errno 54))	; Connection reset by peer
+(define errno/nobufs (hurd-errno 55))		; No buffer space available
+(define errno/isconn (hurd-errno 56))		; Transport endpoint is already connected
+(define errno/notconn (hurd-errno 57))		; Transport endpoint is not connected
+(define errno/shutdown (hurd-errno 58))		; Cannot send after transport endpoint shutdown
+(define errno/toomanyrefs (hurd-errno 59))	; Too many references: cannot splice
+(define errno/timedout (hurd-errno 60))		; Connection timed out
+(define errno/connrefused (hurd-errno 61))	; Connection refused
+(define errno/loop (hurd-errno 62))		; Too many levels of symbolic links
+(define errno/nametoolong (hurd-errno 63))	; File name too long
+(define errno/hostdown (hurd-errno 64))		; Host is down
+(define errno/hostunreach (hurd-errno 65))	; No route to host
+(define errno/notempty (hurd-errno 66))		; Directory not empty
+(define errno/proclim (hurd-errno 67))		; Too many processes
+(define errno/users (hurd-errno 68))		; Too many users
+(define errno/dquot (hurd-errno 69))		; Disk quota exceeded
+(define errno/stale (hurd-errno 70))		; Stale NFS file handle
+(define errno/remote (hurd-errno 71))		; Object is remote
+(define errno/badrpc (hurd-errno 72))		; RPC struct is bad
+(define errno/rpcmismatch (hurd-errno 73))	; RPC version wrong
+(define errno/progunavail (hurd-errno 74))	; RPC program not available
+(define errno/progmismatch (hurd-errno 75))	; RPC program version wrong
+(define errno/procunavail (hurd-errno 76))	; RPC bad procedure for program
+(define errno/nolck (hurd-errno 77))		; No locks available
+(define errno/nosys (hurd-errno 78))		; Function not implemented
+(define errno/ftype (hurd-errno 79))		; Inappropriate file type or format
+(define errno/auth (hurd-errno 80))		; Authentication error
+(define errno/needauth (hurd-errno 81))		; Need authenticator
+(define errno/background (hurd-errno 100))	; Inappropriate operation for background process
+(define errno/died (hurd-errno 101))		; Translator died
+(define errno/d (hurd-errno 102))		; ?
+(define errno/gregious (hurd-errno 103))	; You really blew it this time
+(define errno/ieio (hurd-errno 104))		; Computer bought the farm
+(define errno/gratuitous (hurd-errno 105))	; Gratuitous error
+(define errno/ilseq (hurd-errno 106))		; Invalid or incomplete multibyte or wide character
+(define errno/badmsg (hurd-errno 107))		; Bad message
+(define errno/idrm (hurd-errno 108))		; Identifier removed
+(define errno/multihop (hurd-errno 109))	; Multihop attempted
+(define errno/nodata (hurd-errno 110))		; No data available
+(define errno/nolink (hurd-errno 111))		; Link has been severed
+(define errno/nomsg (hurd-errno 112))		; No message of desired type
+(define errno/nosr (hurd-errno 113))		; Out of streams resources
+(define errno/nostr (hurd-errno 114))		; Device not a stream
+(define errno/overflow (hurd-errno 115))	; Value too large for defined data type
+(define errno/proto (hurd-errno 116))		; Protocol error
+(define errno/time (hurd-errno 117))		; Timer expired
+(define errno/canceled (hurd-errno 118))	; Operation cancelled
+(define errno/notsup (hurd-errno 118))		; Not supported
diff --git a/scsh/gnu/fdflags.scm b/scsh/gnu/fdflags.scm
new file mode 100644
index 0000000..3ba4ad4
--- /dev/null
+++ b/scsh/gnu/fdflags.scm
@@ -0,0 +1,59 @@
+;;; Flags for open(2) and fcntl(2).
+;;; Copyright (c) 1993 by Olin Shivers. See file COPYING.
+
+(define-enum-constants open
+  ;; POSIX
+  (read			#x0001)		; Open for reading
+  (write		#x0002)		; Open for writing
+  (read+write		#x0003)		; Open for reading and writing
+  (non-blocking		#x0008)		; Non-blocking open or non-blocking I/O
+  (append		#x0100)		; Writes always append to the file
+  (no-control-tty	0)		; Don't assign a controlling terminal
+  (create               #x0010)		; Create file if it doesn't exist
+  (truncate             #x00010000)	; Truncate file to zero length
+  (exclusive            #x0020)		; Fail if file already exists
+
+  ;; BSD
+  (shared-lock		#x00020000)	; Open with shared file lock
+  (exclusive-lock	#x00040000)	; Open with exclusive file lock
+  (async		#x0200)		; Send SIGIO to owner when data is ready
+  (fsync 	        #x0400)		; Synchronous writes
+
+  ;; GNU
+  (execute		#x0004)		; Open for execution
+  (no-link		#x0040)		; No name mappings on final component
+  (no-translator	#x0080)		; No translator on final component
+  (no-access-time	#x0800)		; Don't set access time on read
+  (ignore-control-tty	#x00080000))	; Don't do any ctty magic at all
+
+(define open/access-mask
+  (bitwise-ior open/read
+	       (bitwise-ior open/write open/read+write)))
+
+;;; fcntl() commands
+(define-enum-constants fcntl
+  (dup-fdes			0)      ; F_DUPFD
+  (get-fdes-flags		1)      ; F_GETFD
+  (set-fdes-flags		2)      ; F_SETFD
+  (get-status-flags		3)      ; F_GETFL
+  (set-status-flags		4)      ; F_SETFL
+  (get-owner			5)	; F_GETOWN (Not POSIX)
+  (set-owner			6)	; F_SETOWN (Not POSIX)
+  (get-record-lock		7)	; F_GETLK
+  (set-record-lock-no-block	8)	; F_SETLK
+  (set-record-lock		9))	; F_SETLKW
+
+;;; fcntl fdes-flags (F_GETFD)
+
+(define fdflags/close-on-exec 		1)
+
+;;; fcntl status-flags (F_GETFL)
+;;; Mostly, these are OPEN/... flags, like OPEN/APPEND.
+;;; (define fdstatus/... ...)
+
+;;; fcntl lock values.
+
+(define-enum-constants lock
+  (read		1)	; F_RDLCK
+  (write	2)	; F_WRLCK
+  (release	3))	; F_UNLCK
diff --git a/scsh/gnu/libansi.c b/scsh/gnu/libansi.c
new file mode 100644
index 0000000..410d332
--- /dev/null
+++ b/scsh/gnu/libansi.c
@@ -0,0 +1,4 @@
+/* OS-dependent support for what is supposed to be the standard ANSI C Library.
+** Copyright (c) 1996 by Brian D. Carlstrom.
+*/
+
diff --git a/scsh/gnu/netconst.scm b/scsh/gnu/netconst.scm
new file mode 100644
index 0000000..8bdc5de
--- /dev/null
+++ b/scsh/gnu/netconst.scm
@@ -0,0 +1,139 @@
+;;; Magic Numbers for Networking
+;;; Copyright (c) 1994 by Brian D. Carlstrom. See file COPYING.
+
+;;; magic numbers not from header file
+;;; but from man page
+;;; why can't unix make up its mind
+(define shutdown/receives 0)
+(define shutdown/sends 1)
+(define shutdown/sends+receives 2)
+
+;;;-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+;;; BELOW THIS POINT ARE BITS FROM:
+;;; <sys/socket.h> 
+;;; <sys/un.h> 
+;;; <netinet/in.h>
+;;; <netinet/tcp.h>
+;;; <netdb.h>
+;;;-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+
+;;; ADDRESS FAMILIES -- <sys/socket.h>
+(define address-family/unspecified 0)	; unspecified
+(define address-family/unix 1)		; local to host (pipes, portals)
+(define address-family/internet 2)	; internetwork: UDP, TCP, etc.
+
+;;; SOCKET TYPES -- <sys/socket.h>
+(define socket-type/stream 1)		; stream socket 
+(define socket-type/datagram 2)		; datagram socket
+(define socket-type/raw 3)		; raw-protocol interface
+;;(define socket-type/rdm 4)		; reliably-delivered message
+;;(define socket-type/seqpacket 5)      ; sequenced packet stream
+
+;;; PROTOCOL FAMILIES -- <sys/socket.h>
+(define protocol-family/unspecified 0)	; unspecified
+(define protocol-family/unix 1)		; local to host (pipes, portals)
+(define protocol-family/internet 2)	; internetwork: UDP, TCP, etc.
+
+;;; Well know addresses -- <netinet/in.h>
+(define internet-address/any #x00000000)
+(define internet-address/loopback #x7f000001)
+(define internet-address/broadcast #xffffffff)	; must be masked
+
+;;; errors from host lookup -- <netdb.h>
+(define	herror/host-not-found 1) ;Authoritative Answer Host not found
+(define	herror/try-again   2) ;Non-Authoritive Host not found, or SERVERFAIL
+(define	herror/no-recovery 3) ;Non recoverable errors, FORMERR, REFUSED, NOTIMP
+(define	herror/no-data     4) ;Valid name, no data record of requested type
+(define	herror/no-address herror/no-data) ;no address, look for MX record
+
+;;; flags for send/recv -- <sys/socket.h>
+(define message/out-of-band  1) ; process out-of-band data
+(define message/peek         2) ; peek at incoming message
+(define message/dont-route   4) ; send without using routing tables
+(define	message/eor          8) ; data completes record
+(define	message/trunc	  #x10)	; data discarded before delivery
+(define	message/ctrunc	  #x20)	; control data lost before delivery
+(define	message/wait-all  #x40)	; wait for full request or error
+(define	message/dont-wait #x80)	; this message should be nonblocking
+
+;;; protocol level for socket options -- <sys/socket.h>
+(define level/socket #xffff)		; SOL_SOCKET: options for socket level
+
+;;; socket options -- <sys/socket.h>
+(define socket/debug #x0001)		; turn on debugging info recording 
+(define socket/accept-connect #x0002)	; socket has had listen() 
+(define socket/reuse-address #x0004)	; allow local address reuse 
+(define socket/keep-alive #x0008)	; keep connections alive 
+(define socket/dont-route #x0010)	; just use interface addresses 
+(define socket/broadcast #x0020)	; permit sending of broadcast msgs 
+(define socket/use-loop-back #x0040)	; bypass hardware when possible 
+(define socket/linger	#x0080)		; linger on close if data present 
+(define socket/oob-inline #x0100)	; leave received OOB data in line 
+(define socket/reuse-port #x0200)	; allow local address & port reuse
+;(define socket/use-privileged #x4000)	; allocate from privileged port area 
+;(define socket/cant-signal #x8000)	; prevent SIGPIPE on SS_CANTSENDMORE 
+(define socket/send-buffer #x1001)	; send buffer size 
+(define socket/receive-buffer #x1002)	; receive buffer size 
+(define socket/send-low-water #x1003)	; send low-water mark 
+(define socket/receive-low-water #x1004) ; receive low-water mark 
+(define socket/send-timeout #x1005)	; send timeout 
+(define socket/receive-timeout #x1006)	; receive timeout 
+(define socket/error #x1007)		; get error status and clear 
+(define socket/type #x1008)		; get socket type 
+
+;;; ip options -- <netinet/in.h>
+(define	ip/options		1    ) ; buf/ip/opts; set/get ip options
+(define	ip/header-included	2    ) ; int; header is included with data
+(define	ip/type-of-service	3    ) ; int; ip type of service and preced.
+(define	ip/time-to-live		4    ) ; int; ip time to live
+(define	ip/receive-options	5    ) ; bool; receive all ip opts w/dgram
+(define	ip/response-options	6    ) ; bool; receive ip opts for response
+(define	ip/destination-address	7    ) ; bool; receive ip dst addr w/dgram
+(define	ip/ret-options		8    ) ; ip_opts; set/get ip options
+(define	ip/multicast-if		9    ) ; u_char; set/get ip multicast i/f 
+(define	ip/multicast-ttl	10   ) ; u_char; set/get ip multicast ttl
+(define	ip/multicast-loop	11   ) ; u_char; set/get ip multicast loopback
+(define	ip/add-membership	12   ) ; ip_mreq; add an ip group membership
+(define	ip/drop-membership	13   ) ; ip_mreq; drop an ip group membership
+
+;;; tcp options -- <netinet/tcp.h>
+(define tcp/no-delay #x01)		; don't delay send to coalesce packets
+(define tcp/max-segment #x02)		; set maximum segment size
+
+;;; -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+;;; OPTION SETS FOR SOCKET-OPTION AND SET-SOCKET-OPTION
+
+;;; Boolean Options
+(define options/boolean
+  (list socket/debug
+	socket/accept-connect
+	socket/reuse-address
+	socket/keep-alive
+	socket/dont-route
+	socket/broadcast
+	socket/use-loop-back
+	socket/oob-inline
+	socket/reuse-port		;BSD4.4-Lite
+;	socket/use-privileged
+;	socket/cant-signal
+	tcp/no-delay))
+
+;;; Integer Options
+(define options/value
+  (list socket/send-buffer
+	socket/receive-buffer
+	socket/send-low-water
+	socket/receive-low-water
+	socket/error
+	socket/type
+	ip/time-to-live
+	tcp/max-segment))
+
+;;; #f or Positive Integer
+(define options/linger
+  (list socket/linger))
+
+;;; Real Number
+(define options/timeout
+  (list socket/send-timeout
+	socket/receive-timeout))
diff --git a/scsh/gnu/packages.scm b/scsh/gnu/packages.scm
new file mode 100644
index 0000000..0442d14
--- /dev/null
+++ b/scsh/gnu/packages.scm
@@ -0,0 +1,163 @@
+;;; Interfaces and packages for the GNU Hurd specific parts of scsh.
+;;; Copyright (c) 1994 by Olin Shivers. See file COPYING.
+
+(define-interface gnu-fdflags-extras-interface
+  (export open/shared-lock
+	  open/exclusive-lock
+	  open/async
+	  open/fsync
+	  open/execute
+	  open/no-link
+	  open/no-translator
+	  open/no-access-time
+	  open/ignore-control-tty
+	  fcntl/get-owner
+	  fcntl/set-owner))
+
+(define-interface gnu-errno-extras-interface
+  (export errno/notblk
+	  errno/txtbsy
+	  errno/nospc
+	  errno/wouldblock
+	  errno/inprogress
+	  errno/already
+	  errno/notsock
+	  errno/destaddrreq
+	  errno/msgsize
+	  errno/prototype
+	  errno/noprotoopt
+	  errno/protonosupport
+	  errno/socktnosupport
+	  errno/opnotsupp
+	  errno/pfnosupport
+	  errno/afnosupport
+	  errno/addrinuse
+	  errno/addrnotavail
+	  errno/netdown
+	  errno/netunreach
+	  errno/netreset
+	  errno/connaborted
+	  errno/connreset
+	  errno/nobufs
+	  errno/isconn
+	  errno/notconn
+	  errno/shutdown
+	  errno/toomanyrefs
+	  errno/timedout
+	  errno/connrefused
+	  errno/loop
+	  errno/hostdown
+	  errno/hostunreach
+	  errno/proclim
+	  errno/users
+	  errno/dquot
+	  errno/stale
+	  errno/remote
+	  errno/badrpc
+	  errno/rpcmismatch
+	  errno/progunavail
+	  errno/progmismatch
+	  errno/procunavail
+	  errno/ftype
+	  errno/auth
+	  errno/needauth
+	  errno/background
+	  errno/died
+	  errno/d
+	  errno/gregious
+	  errno/ieio
+	  errno/gratuitous
+	  errno/ilseq
+	  errno/badmsg
+	  errno/idrm
+	  errno/multihop
+	  errno/nodata
+	  errno/nolink
+	  errno/nomsg
+	  errno/nosr
+	  errno/nostr
+	  errno/overflow
+	  errno/proto
+	  errno/time
+	  errno/canceled
+	  errno/notsup))
+
+(define-interface gnu-signals-extras-interface
+  (export signal/trap
+	  signal/emt
+	  signal/bus
+	  signal/sys
+	  signal/urg
+	  signal/cld
+	  signal/io
+	  signal/xcpu
+	  signal/xfsz
+	  signal/vtalrm
+	  signal/prof
+	  signal/winch
+	  signal/info
+	  signal/lost))
+
+(define-interface gnu-network-extras-interface
+  (export socket/debug
+	  socket/accept-connect
+	  socket/reuse-address
+	  socket/keep-alive
+	  socket/dont-route
+	  socket/broadcast
+	  socket/use-loop-back
+	  socket/linger
+	  socket/oob-inline
+	  socket/reuse-port		;bsd44lite
+;	  socket/use-privileged
+;	  socket/cant-signal
+	  socket/send-buffer
+	  socket/receive-buffer
+	  socket/send-low-water
+	  socket/receive-low-water
+	  socket/send-timeout
+	  socket/receive-timeout
+	  socket/error
+	  socket/type
+;;; all ip/* but ip/options and ip/time-to-live bsd44lite only
+	  ip/options
+	  ip/header-included
+	  ip/type-of-service
+	  ip/time-to-live		
+	  ip/receive-options	
+	  ip/response-options	
+	  ip/destination-address	
+	  ip/ret-options		
+	  ip/multicast-if		
+	  ip/multicast-ttl	
+	  ip/multicast-loop	
+	  ip/add-membership	
+	  ip/drop-membership	
+	  tcp/no-delay
+	  tcp/max-segment
+	  message/eor
+	  message/trunc
+	  message/ctrunc
+	  message/wait-all
+	  message/dont-wait))
+
+(define-interface gnu-extras-interface
+  (compound-interface gnu-errno-extras-interface
+		      gnu-fdflags-extras-interface
+		      gnu-network-extras-interface
+		      gnu-signals-extras-interface))
+
+(define-interface gnu-defs-interface
+  (compound-interface gnu-extras-interface
+		      sockets-network-interface
+		      posix-errno-interface
+		      posix-fdflags-interface
+		      posix-signals-interface
+		      signals-internals-interface))
+
+(define-structure gnu-defs gnu-defs-interface
+  (open scheme bitwise defenum-package)
+  (files fdflags errno signals netconst))
+
+(define-interface os-extras-interface gnu-extras-interface)
+(define os-dependent gnu-defs)
diff --git a/scsh/gnu/signals.scm b/scsh/gnu/signals.scm
new file mode 100644
index 0000000..4b52fec
--- /dev/null
+++ b/scsh/gnu/signals.scm
@@ -0,0 +1,76 @@
+;;; Signal constant definitions for the GNU Hurd
+;;; Copyright (c) 1994 by Olin Shivers. See file COPYING.
+;;; Copyright (c) 1994 by Brian D. Carlstrom.
+
+(define-enum-constants signal
+  ;; POSIX
+  (hup	1)	; hangup 
+  (int	2)	; interrupt 
+  (quit	3)	; quit 
+  (ill	4)	; illegal instruction (not reset when caught) 
+
+  ;; BSD4.4-Lite
+  (trap	5)	; trace trap (not reset when caught) 
+
+  ;; POSIX
+  (iot	6)	; IOT instruction 
+  (abrt 6)	; used by abort, replace SIGIOT in the future 
+
+  ;; BSD4.4-Lite
+  (emt	7)	; EMT instruction 
+
+  ;; POSIX
+  (fpe	8)	; floating point exception 
+  (kill	9)	; kill (cannot be caught or ignored) 
+
+  ;; BSD4.4-Lite
+  (bus	10)	; bus error 
+
+  ;; POSIX
+  (segv	11)	; segmentation violation
+
+  ;; BSD4.4-Lite
+  (sys	12)	; bad argument to system call
+
+  ;; POSIX
+  (pipe	13)	; write on a pipe with no one to read it 
+  (alrm	14)	; alarm clock 
+  (term	15)	; software termination signal from kill 
+
+  ;; BSD4.4-Lite
+  (urg	16)	; urgent condition on IO channel 
+
+  ;; POSIX
+  (stop	17)	; sendable stop signal not from tty 
+  (tstp	18)	; stop signal from tty 
+  (cont	19)	; continue a stopped process 
+  (chld	20)	; to parent on child stop or exit 
+
+  ;; BSD4.4-Lite
+  (cld	20)	; System V name for SIGCHLD 
+
+  ;; POSIX
+  (ttin	21)	; to readers pgrp upon background tty read 
+  (ttou	22)	; like TTIN for output if (tp->t_local&LTOSTOP) 
+
+  ;; BSD4.4-Lite
+  (io	23)	; input/output possible signal 
+  (poll	23)	; System V name for SIGIO 
+  (xcpu	24)	; exceeded CPU time limit 
+  (xfsz	25)	; exceeded file size limit 
+  (vtalrm 26)	; virtual time alarm 
+  (prof	27)	; profiling time alarm 
+  (winch 28)	; window changed 
+  (info 29)	; information request
+
+  ;; User defined
+  (usr1 30)	; user defined signal 1 
+  (usr2 31)	; user defined signal 2 
+
+  ;; GNU
+  (lost 32)	; server died
+  )
+
+(define signals-ignored-by-default
+  (list signal/chld signal/cont				; These are Posix.
+	signal/info signal/io signal/urg signal/winch)) ; These are BSD.
diff --git a/scsh/gnu/sysdep.h b/scsh/gnu/sysdep.h
new file mode 100644
index 0000000..c9bd059
--- /dev/null
+++ b/scsh/gnu/sysdep.h
@@ -0,0 +1 @@
+/* Make `diff' happy. */
diff --git a/scsh/gnu/time_dep.scm b/scsh/gnu/time_dep.scm
new file mode 100644
index 0000000..b9b2063
--- /dev/null
+++ b/scsh/gnu/time_dep.scm
@@ -0,0 +1,8 @@
+;;; OS-dependent time stuff
+;;; Copyright (c) 1995 by Olin Shivers. See file COPYING.
+
+;;; This suffices for BSD systems with the gettimeofday()
+;;; microsecond-resolution timer.
+
+(define (ticks/sec) 1000000) ; usec
+
diff --git a/scsh/gnu/tty-consts.scm b/scsh/gnu/tty-consts.scm
new file mode 100644
index 0000000..45e8935
--- /dev/null
+++ b/scsh/gnu/tty-consts.scm
@@ -0,0 +1,216 @@
+;;; Constant definitions for tty control code (POSIX termios).
+;;; Copyright (c) 1995 by Brian Carlstrom. See file COPYING.
+;;; Largely rehacked by Olin.
+
+;;; These constants are for the GNU Hurd.
+;;; and are taken from /usr/include/bits/termios.h.
+
+;;; Non-standard (POSIX, SVR4, 4.3+BSD) things:
+;;; - Some of the baud rates.
+
+
+;;; Special Control Characters 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;  Indices into the c_cc[] character array.
+
+;;;	Name	     		Subscript	Enabled by 
+;;;     ----         		---------	----------
+;;;  POSIX
+(define ttychar/eof		0)		; ^d icanon
+(define ttychar/eol		1)		;    icanon
+
+(define ttychar/delete-char	3)		; ^? icanon
+
+(define ttychar/delete-line	5)		; ^u icanon
+
+(define ttychar/interrupt	8)		; ^c isig
+(define ttychar/quit		9)		; ^\ isig
+(define ttychar/suspend		10)		; ^z isig
+
+(define ttychar/start		12)		; ^q ixon, ixoff
+(define ttychar/stop		13)		; ^s ixon, ixoff
+(define ttychar/min		16)		;    !icanon	; Not exported
+(define ttychar/time		17)		;    !icanon	; Not exported
+
+;;; SVR4 & 4.3+BSD
+(define ttychar/eol2		2)		;    icanon
+(define ttychar/delete-word	4)		; ^w icanon
+(define ttychar/reprint 	6)		; ^r icanon
+(define ttychar/delayed-suspend	11)		; ^y isig
+(define ttychar/literal-next	14)		; ^v iexten
+(define ttychar/discard		15)		; ^o iexten
+
+;;; 4.3+BSD
+(define ttychar/status		18)		; ^t icanon 
+
+;;; Length of control-char string -- *Not Exported*
+(define	num-ttychars		20)
+
+;;; Magic "disable feature" tty character
+(define disable-tty-char (ascii->char #xff))	; _POSIX_VDISABLE
+
+;;; Flags controllling input processing
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+;;;  POSIX
+(define ttyin/ignore-break		#x00001)	; ignbrk
+(define ttyin/interrupt-on-break	#x00002)	; brkint
+(define ttyin/ignore-bad-parity-chars	#x00004)	; ignpar
+(define ttyin/mark-parity-errors	#x00008)	; parmrk
+(define ttyin/check-parity		#x00010)	; inpck
+(define ttyin/7bits			#x00020)	; istrip
+(define ttyin/nl->cr			#x00040)	; inlcr
+(define ttyin/ignore-cr			#x00080)	; igncr
+(define ttyin/cr->nl			#x00100)	; icrnl
+(define ttyin/output-flow-ctl		#x00200)	; ixon
+(define ttyin/input-flow-ctl		#x00400)	; ixoff
+
+;;; SVR4 & 4.3+BSD
+(define ttyin/xon-any	       #x00800)	; ixany: Any char restarts after stop
+(define ttyin/beep-on-overflow #x02000)	; imaxbel: queue full => ring bell
+
+;;; SVR4
+(define ttyin/lowercase	       #x04000)	; iuclc: Map upper-case to lower case
+
+
+;;; Flags controlling output processing
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+;;;  POSIX 
+(define	ttyout/enable		 #x000001)  ; opost: enable output processing
+
+;;; SVR4 & 4.3+BSD
+(define ttyout/nl->crnl		 #x000002)	; onlcr: map nl to cr-nl
+
+;;; 4.3+BSD
+(define ttyout/discard-eot	 #x000008)	; onoeot
+(define ttyout/expand-tabs	 #x000004)	; oxtabs (NOT xtabs)
+
+;;; SVR4
+(define ttyout/cr->nl		 #f)		; ocrnl
+(define ttyout/fill-w/del	 #f)		; ofdel
+(define ttyout/delay-w/fill-char #f)		; ofill
+(define ttyout/uppercase	 #x000200)	; olcuc
+(define ttyout/nl-does-cr	 #f)		; onlret
+(define ttyout/no-col0-cr	 #f)		; onocr
+
+;;; Newline delay
+(define	ttyout/nl-delay		#f)	; mask (nldly)
+(define	 ttyout/nl-delay0	#f)
+(define	 ttyout/nl-delay1	#f)	; tty 37 
+
+;;; Horizontal-tab delay
+(define	ttyout/tab-delay	#f)	; mask (tabdly)
+(define	 ttyout/tab-delay0	#f)
+(define	 ttyout/tab-delay1	#f)	; tty 37 
+(define	 ttyout/tab-delay2	#f)
+(define	 ttyout/tab-delayx	#f)	; Expand tabs (xtabs, tab3)
+
+;;; Carriage-return delay
+(define	ttyout/cr-delay		#f)	; mask (crdly)
+(define	 ttyout/cr-delay0	#f)
+(define	 ttyout/cr-delay1	#f)	; tn 300 
+(define	 ttyout/cr-delay2	#f)	; tty 37 
+(define	 ttyout/cr-delay3	#f)	; concept 100 
+
+;;; Vertical tab delay 
+(define	ttyout/vtab-delay	#f)	; mask (vtdly)
+(define	 ttyout/vtab-delay0	#f)
+(define	 ttyout/vtab-delay1	#f)	; tty 37 
+
+;;; Backspace delay
+(define	ttyout/bs-delay		#f)	; mask (bsdly)
+(define	 ttyout/bs-delay0	#f)
+(define	 ttyout/bs-delay1	#f)
+
+;;; Form-feed delay
+(define ttyout/ff-delay		#f)	; mask (ffdly)
+(define	 ttyout/ff-delay0	#f)
+(define	 ttyout/ff-delay1	#f)
+
+(define	ttyout/all-delay	#f)
+
+;;; Control flags - hacking the serial-line.
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+;;;  POSIX
+(define ttyc/char-size		#x00300)	; csize: character size mask 
+(define  ttyc/char-size5	#x00000)	; 5 bits (cs5)
+(define  ttyc/char-size6	#x00100)	; 6 bits (cs6)
+(define  ttyc/char-size7	#x00200)	; 7 bits (cs7)
+(define  ttyc/char-size8	#x00300)	; 8 bits (cs8)
+(define ttyc/2-stop-bits	#x00400)	; cstopb: Send 2 stop bits.
+(define ttyc/enable-read	#x00800)	; cread: Enable receiver.
+(define ttyc/enable-parity	#x01000)	; parenb
+(define ttyc/odd-parity		#x02000)	; parodd
+(define ttyc/hup-on-close	#x04000)	; hupcl: Hang up on last close.
+(define ttyc/no-modem-sync	#x08000)	; clocal: Ignore modem lines.
+
+;;;  4.3+BSD
+(define	ttyc/ignore-flags	#x00001)	; cignore: ignore control flags 
+(define ttyc/CTS-output-flow-ctl #x00010000)	; ccts_oflow: CTS flow control of output
+(define ttyc/RTS-input-flow-ctl  #x00020000)	; crts_iflow: RTS flow control of input
+(define ttyc/carrier-flow-ctl	 #x00100000)	; mdmbuf
+
+;;; Local flags -- hacking the tty driver / user interface.
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+;;;  POSIX
+(define ttyl/visual-delete    #x00000002)	; echoe: Visually erase chars
+(define ttyl/echo-delete-line #x00000004)	; echok: Echo nl after line kill
+(define ttyl/echo	      #x00000008)	; echo:  Enable echoing
+(define ttyl/echo-nl	      #x00000010)	; echonl: Echo nl even if echo is off
+(define ttyl/canonical	      #x00000100)	; icanon: Canonicalize input
+(define ttyl/enable-signals   #x00000080)	; isig: Enable ^c, ^z signalling
+(define ttyl/extended	      #x00000400)	; iexten:  Enable extensions
+(define ttyl/ttou-signal      #x00400000)	; tostop: SIGTTOU on background output
+(define ttyl/no-flush-on-interrupt #x80000000) ; noflsh
+
+;;; SVR4 & 4.3+BSD
+(define ttyl/visual-delete-line #x00000001); echoke: visually erase a line-kill 
+(define ttyl/hardcopy-delete	#x00000020); echoprt: visual erase for hardcopy 
+(define ttyl/echo-ctl		#x00000040); echoctl: echo control chars as "^X" 
+(define ttyl/flush-output	#x00800000); flusho: output is being flushed
+(define ttyl/reprint-unread-chars #x20000000); pendin: retype pending input
+
+;;; 4.3+BSD
+(define ttyl/alt-delete-word	#x00000200)	; altwerase
+(define ttyl/no-kernel-status	#x02000000)	; nokerninfo: no kernel status on ^T
+
+;;; SVR4
+(define ttyl/case-map #f)	; xcase: canonical upper/lower presentation
+
+;;; Vector of (speed . code) pairs.
+
+(define baud-rates '#((0      . 0)	(50     . 50)	  (75     . 75)
+		      (110    . 110)	(134    . 134)	  (150    . 150)
+		      (200    . 200)	(300    . 300)	  (600    . 600)
+		      (1200   . 1200)	(1800   . 1800)   (2400   . 2400)	
+		      (4800   . 4800)   (9600   . 9600)   (19200  . 19200)
+		      (38400  . 38400)	(19200  . exta)   (38400  . extb)
+		      (57600  . 57600)	(115200 . 115200) (230400 . 230400)))
+
+;;; tcflush() constants
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(define %flush-tty/input  1)	; TCIFLUSH
+(define %flush-tty/output 2)    ; TCOFLUSH
+(define %flush-tty/both	  3)	; TCIOFLUSH
+
+
+;;; tcflow() constants
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(define %tcflow/start-out 2)	; TCOON
+(define %tcflow/stop-out  1)	; TCOOFF
+(define %tcflow/start-in  4)	; TCION
+(define %tcflow/stop-in   3)	; TCIOFF
+
+
+;;; tcsetattr() constants
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(define %set-tty-info/now	0)	; TCSANOW   Make change immediately.
+(define %set-tty-info/drain	1)	; TCSADRAIN Drain output, then change.
+(define %set-tty-info/flush	2)	; TCSAFLUSH Drain output, flush input.
+(define %set-tty-info/soft	#x10)	; flag: don't alter h.w. state 
diff --git a/scsh/gnu/waitcodes.scm b/scsh/gnu/waitcodes.scm
new file mode 100644
index 0000000..2c2ecc0
--- /dev/null
+++ b/scsh/gnu/waitcodes.scm
@@ -0,0 +1,39 @@
+;;; Scsh routines for analysing exit codes returned by WAIT.
+;;; Copyright (c) 1994 by Olin Shivers. See file COPYING.
+;;;
+;;; To port these to a new OS, consult /usr/include/sys/wait.h, 
+;;; and check the WIFEXITED, WEXITSTATUS, WIFSTOPPED, WSTOPSIG, 
+;;; WIFSIGNALED, and WTERMSIG macros for the magic fields they use.
+;;; These definitions are for Linux.
+;;;
+;;; I could have done a portable version by making C calls for this,
+;;; but it's such overkill.
+
+
+;;; If process terminated normally, return the exit code, otw #f.
+
+(define (status:exit-val status)
+  (and (zero? (bitwise-and #x7F status))
+       (bitwise-and #xFF (arithmetic-shift status -8))))
+
+
+;;; If the process was suspended, return the suspending signal, otw #f.
+
+(define (status:stop-sig status)
+  (and (= #x7F (bitwise-and status #xFF))
+       (bitwise-and #xFF (arithmetic-shift status -8))))
+
+
+;;; If the process terminated abnormally, 
+;;; return the terminating signal, otw #f.
+
+(define (status:term-sig status)
+  (let ((termsig (bitwise-and status #x7F)))
+    (and (not (zero? termsig))				; Didn't exit.
+	 (not (= #x7F (bitwise-and status #xFF)))	; Not suspended.
+	 termsig)))
+
+
+;;; Flags.
+(define wait/poll 		1)	; Don't hang if nothing to wait for.
+(define wait/stopped-children	2)	; Report on suspended subprocs, too.