sz.doc

通讯程序源码

     SSSSZZZZ((((1111))))		OOOOmmmmeeeennnn TTTTeeeecccchhhhnnnnoooollllooooggggyyyy	IIIINNNNCCCC ((((OOOOMMMMEEEENNNN))))		 SSSSZZZZ((((1111))))



	  yyyy    Instruct	a ZMODEM receiving program to overwrite	any
	       existing	file with the same name.
	  YYYY    Instruct	a ZMODEM receiving program to overwrite	any
	       existing	file with the same name, and to	skip any
	       source files that do have a file	with the same pathname
	       on the destination system.
	  ZZZZ    Use ZMODEM file compression to speed file transfer.

     DDDDIIIIAAAAGGGGNNNNOOOOSSSSTTTTIIIICCCCSSSS
	  Exit status is as follows: 0 for successful transfers.  1 if
	  unrecoverable	errors are detected.  2	if syntax errors or
	  file access problems are detected.  3	if the program was
	  terminated by	a caught interrupt.

     EEEEXXXXAAAAMMMMPPPPLLLLEEEESSSS
	  ZZZZMMMMOOOODDDDEEEEMMMM FFFFiiiilllleeee TTTTrrrraaaannnnssssffffeeeerrrr (Unix to	DSZ/ZCOMM/Professional-YAM)
	  %%%% sssszzzz ----aaaa ****....cccc
	  This single command transfers	all .c files in	the current
	  Unix directory with conversion (----aaaa) to end of	line
	  conventions appropriate to the receiving environment.	 With
	  ZMODEM AutoDownload enabled, Professional-YAM	 and ZCOMM
	  will automatically recieve the files after performing	a
	  security check.

	  %%%% sssszzzz ----YYYYaaaannnn ****....cccc	****....hhhh
	  Send only the	.c and .h files	that exist on both systems,
	  and are newer	on the sending system than the corresponding
	  version on the receiving system, converting Unix to DOS text
	  format.

	  ZZZZMMMMOOOODDDDEEEEMMMM CCCCoooommmmmmmmaaaannnndddd DDDDoooowwwwnnnnllllooooaaaadddd (Unix	to Professional-YAM)
	   cpszall:all
	      zcommand "c:;cd /yam/dist"
	      sz -ya $(YD)/*.me
	      sz -yb y*.exe
	      zcommand "cd /yam"
	      zcommandi	"!insms"
	  This Makefile	fragment uses zzzzccccoooommmmmmmmaaaannnndddd to issue	commands to
	  Professional-YAM to change current disk and directory.
	  Next,	sssszzzz transfers the ._m_e files from	the $YD	directory,
	  commanding the receiver to overwrite the old files and to
	  convert from Unix end	of line	conventions to PC-DOS
	  conventions.	The third line transfers some ._e_x_e files.  The
	  fourth and fifth lines command Pro-YAM to change directory
	  and execute a	PC-DOS batch file _i_n_s_m_s	. Since	the batch file
	  takes	considerable time, the zzzzccccoooommmmmmmmaaaannnnddddiiii form is used to allow
	  the program to exit immediately.

	  XXXXMMMMOOOODDDDEEEEMMMM FFFFiiiilllleeee TTTTrrrraaaannnnssssffffeeeerrrr (Unix to	Crosstalk)
	  % ssssxxxx ffffoooooooo....cccc
	  EEEESSSSCCCC
	  rrrrxxxx ffffoooooooo....cccc



     Page 4					    (printed 12/15/91)






     SSSSZZZZ((((1111))))		OOOOmmmmeeeennnn TTTTeeeecccchhhhnnnnoooollllooooggggyyyy	IIIINNNNCCCC ((((OOOOMMMMEEEENNNN))))		 SSSSZZZZ((((1111))))



	  The above three commands transfer a single file from Unix to
	  a PC and Crosstalk.  This combination	is much	slower and
	  less reliable	than ZMODEM.

     EEEERRRRRRRROOOORRRR MMMMEEEESSSSSSSSAAAAGGGGEEEESSSS
	  "Caught signal 99" indicates the program was not properly
	  compiled, refer to "bibi(99)"	in rbsb.c for details.

     SSSSEEEEEEEE AAAALLLLSSSSOOOO
	  rz(omen), ZMODEM.DOC,	YMODEM.DOC, Professional-YAM,
	  crc(omen), sq(omen), todos(omen), tocpm(omen), tomac(omen),
	  yam(omen)

	  Compile time options required	for various operating systems
	  are described	in the source file.

     FFFFIIIILLLLEEEESSSS
	  32 bit CRC code courtesy Gary	S. Brown.

	  sz.c,	crctab.c, rbsb.c, zm.c,	zmr.c, zmodem.h	Unix source
	  files

	  /tmp/szlog stores debugging output (sz -vv)

     TTTTEEEESSSSTTTTIIIINNNNGGGG FFFFEEEEAAAATTTTUUUURRRREEEE
	  The command "sz -T file" exercises the AAAAttttttttnnnn sequence error
	  recovery by commanding errors	with unterminated packets.
	  The receiving	program	should complain	five times about
	  binary data packets being too	long.  Each time sssszzzz is
	  interrupted, it should send a	ZDATA header followed by
	  another defective packet.  If	the receiver does not detect
	  five long data packets, the AAAAttttttttnnnn sequence is not
	  interrupting the sender, and the MMMMyyyyaaaattttttttnnnn string in sssszzzz....cccc must
	  be modified.

	  After	5 packets, sssszzzz stops the	"transfer" and prints the
	  total	number of characters "sent" (Tcount).  The difference
	  between Tcount and 5120 represents the number	of characters
	  stored in various buffers when the Attn sequence is
	  generated.

     NNNNOOOOTTTTEEEESSSS
	  We have received numerous reports of terminal	servers
	  interfering with protocol file transfers.  Sometimes special
	  terminal server commands correct the problem.	 In other
	  cases, the terminal server software is defective and must be
	  corrected.

	  When using TrailBlazer or other buffered modems at high
	  speed, particular attention must be paid to flow control.
	  The modem and	Unix must agree	on the flow control method.
	  Sz on	USG (SYS III/V)	systems	uses XON/XOFF flow control.



     Page 5					    (printed 12/15/91)






     SSSSZZZZ((((1111))))		OOOOmmmmeeeennnn TTTTeeeecccchhhhnnnnoooollllooooggggyyyy	IIIINNNNCCCC ((((OOOOMMMMEEEENNNN))))		 SSSSZZZZ((((1111))))



	  If flow control cannot be properly set up, Try a "-w 2048"
	  option to enforce protocol level flow	control.  Experiment
	  with different window	sizes for best results.

	  Telebit modems must not be set to "spoof" UUCP, XMODEM, or
	  KERMIT.  Setting one of these	spoofing modes interferes with
	  other	protoocls.

	  If a program that does not properly implement	the specified
	  file transfer	protocol causes	_s_b to "hang" the port after a
	  failed transfer, either wait for _s_b to time out or keyboard
	  a dozen Ctrl-X characters.  Every reported instance of this
	  problem has been corrected by	using ZCOMM, Pro-YAM, DSZ, or
	  other	program	with a correct implementation of the specified
	  protocol.

	  Many programs	claiming to support YMODEM only	support	XMODEM
	  with 1k blocks, and they often don't get that	quite right.
	  XMODEM transfers add up to 127 garbage bytes per file.
	  XMODEM-1k and	YMODEM-1k transfers use	128 byte blocks	to
	  avoid	extra padding.

	  YMODEM programs use the file length transmitted at the
	  beginning of the transfer to prune the file to the correct
	  length; this may cause problems with source files that grow
	  during the course of the transfer.  This problem does	not
	  pertain to ZMODEM transfers, which preserve the exact	file
	  length unconditionally.

	  Most ZMODEM options are merely passed	to the receiving
	  program; some	programs do not	implement all of these
	  options.

	  Circular buffering and a ZMODEM sliding window should	be
	  used when input is from pipes	instead	of acknowledging
	  frames each 1024 bytes.  If no files can be opened, sssszzzz sends
	  a ZMODEM command to echo a suitable complaint; perhaps it
	  should check for the presence	of at least one	accessible
	  file before getting hot and bothered.

     BBBBUUUUGGGGSSSS
	  On at	least one BSD system, sz would abend it	got within a
	  few kilobytes	of the end of file.  Using the "-w 8192" flag
	  fixed	the problem.  The real cause is	unknown, perhaps a bug
	  in the kernel	TTY output routines.

	  The test mode	leaves a zero length file on the receiving
	  system.







     Page 6					    (printed 12/15/91)