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sz.doc
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1995-03-19
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403 lines
SZ(1) UNIX Programmer's Manual SZ(1)
NAME
sx, sb, sz - XMODEM, YMODEM, ZMODEM file send
SYNOPSIS
sz [-+1abdefkLlNnopqTtuvyY] file ...
sb [-1adfkqtuv] file ...
sx [-1akqtuv] file
sz [-1oqtv] -c COMMAND
sz [-1oqtv] -i COMMAND
DESCRIPTION
Sz uses the ZMODEM, YMODEM or XMODEM error correcting proto-
col to send one or more files over a serial port to a
variety of programs running under PC-DOS, CP/M, Unix, VMS,
and other operating systems.
The first form of sz sends one or more files with ZMODEM
protocol.
ZMODEM greatly simplifies file transfers compared to XMODEM.
In addition to a friendly user interface, ZMODEM provides
Personal Computer and other users an efficient, accurate,
and robust file transfer method.
ZMODEM provides complete END-TO-END data integrity between
application programs. ZMODEM's 32 bit CRC catches errors
that sneak into even the most advanced networks.
Advanced file management features include AutoDownload
(Automatic file Download initiated without user interven-
tion), Crash Recovery, selective file transfers, and preser-
vation of exact file date and length.
>Not implemented in amiga version
> Output from another program may be piped to sz for transmis-
> sion by denoting standard input with "-":
> ps -ef | sz -
> The program output is transmitted with the filename sPID.sz
> where PID is the process ID of the sz program. If the
> environment variable ONAME is set, that is used instead. In
> this case, the Unix command:
> ONAME=con ps -ef|sz -ay -
> will send a "file" to the PC-DOS console display. The -y
> option instructs the receiver to open the file for writing
> unconditionally. The -a option causes the receiver to con-
> vert Unix newlines to PC-DOS carriage returns and linefeeds.
>
The second form is invoked as sb to batch send one or more
files with ZMODEM or YMODEM protocol. The initial ZMODEM
initialization is not sent. When requested by the receiver,
sb supports YMODEM-g with "cbreak" tty mode, XON/XOFF flow
Printed 10/25/87 OMEN 1
SZ(1) UNIX Programmer's Manual SZ(1)
control, and interrupt character set to CAN (^X). YMODEM-g
(Professional-YAM g option) increases throughput over error
free channels (direct connection, X.PC, etc.) by not ack-
nowledging each transmitted sector.
On Unix systems, additional information about the file is
transmitted. If the receiving program uses this informa-
tion, the transmitted file length controls the exact number
of bytes written to the output dataset, and the modify time
and file mode are set accordingly.
The third form of sz is invoked as sx to send a single file
with XMODEM or XMODEM-1k protocol (sometimes incorrectly
called "ymodem"). The user must supply the file name to
both sending and receiving programs.
>Not implemented in amiga version
> Iff sz is invoked with $SHELL set and iff that variable con-
> tains the string rsh or rksh (restricted shell), sz operates
> in restricted mode. Restricted mode restricts pathnames to
> the current directory and PUBDIR (usually
> /usr/spool/uucppublic) and/or subdirectories thereof.
The fourth form sends a single COMMAND to a ZMODEM receiver
for execution. Sz exits with the COMMAND return value. If
COMMAND includes spaces or characters special to the shell,
it must be quoted.
The fifth form sends a single COMMAND to a ZMODEM receiver
for execution. Sz exits as soon as the receiver has
correctly received the command, before it is executed.
If sz is invoked with stdout and stderr to different
datasets, Verbose is set to 2, causing frame by frame pro-
gress reports to stderr. This may be disabled with the q
option.
The meanings of the available options are:
+ Instruct the receiver to append transmitted data to an
existing file (ZMODEM only).
Not implemented in Amiga version
> 1 Use file descriptor 1 for ioctls and reads. By
> default, file descriptor 0 is used. This option allows
> sz to be used with the Professional-YAM $ command.
a Convert NL characters in the transmitted file to CR/LF.
This is done by the sender for XMODEM and YMODEM, by
the receiver for ZMODEM.
b (ZMODEM) Binary override: transfer file without any
translation.
Printed 10/25/87 OMEN 2
SZ(1) UNIX Programmer's Manual SZ(1)
c COMMAND
Send COMMAND to the receiver for execution, return with
COMMAND's exit status.
d Change all instances of "." to "/" in the transmitted
pathname. Thus, C.omenB0000 (which is unacceptable to
MSDOS or CP/M) is transmitted as C/omenB0000. If the
resultant filename has more than 8 characters in the
stem, a "." is inserted to allow a total of eleven.
e Escape all control characters; normally XON, XOFF, DLE,
CR-@-CR, and Ctrl-X are escaped.
f Send Full pathname. Normally directory prefixes are
stripped from the transmitted filename.
i COMMAND
Send COMMAND to the receiver for execution, return
Immediately upon the receiving program's successful
recption of the command.
k (XMODEM/YMODEM) Send files using 1024 byte blocks
rather than the default 128 byte blocks. 1024 byte
packets speed file transfers at high bit rates. (ZMO-
DEM streams the data for the best possible throughput.)
L N Use ZMODEM sub-packets of length N. A larger N (32 <=
N <= 1024) gives slightly higher throughput, a smaller
N speeds error recovery. The default is 128 below 300
baud, 256 above 300 baud, or 1024 above 2400 baud.
l N Wait for the receiver to acknowledge correct data every
N (32 <= N <= 1024) characters. This may be used to
avoid network overrun when XOFF flow control is lack-
ing.
n (ZMODEM) Send each file if destination file does not
exist. Overwrite destination file if source file is
newer than the destination file.
N (ZMODEM) Send each file if destination file does not
exist. Overwrite destination file if source file is
newer or longer than the destination file.
o (ZMODEM) Disable automatic selection of 32 bit CRC.
p (ZMODEM) Protect existing destination files by skipping
transfer if the destination file exists.
q Quiet suppresses verbosity.
r (ZMODEM) Resume interrupted file transfer. If the
source file is longer than the destination file, the
transfer commences at the offset in the source file
that equals the length of the destination file.
t tim
Change timeout to tim tenths of seconds.
u Unlink the file after successful transmission.
v Verbose causes a list of file names to be appended to
/tmp/szlog . More v's generate more output.
y Instruct a ZMODEM receiving program to overwrite any
existing file with the same name.
Y 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
Printed 10/25/87 OMEN 3
SZ(1) UNIX Programmer's Manual SZ(1)
on the destination system.
EXAMPLES
ZMODEM File Transfer
$ sz -a *.c
This single command transfers all .c files in the current
Unix directory with conversion (-a) to end of line conven-
tions appropriate to the receiving environment. With ZMODEM
AutoDownload enabled, Professional-YAM and ZCOMM will
automatically recieve the files after performing a security
check.
$ sz -Yan *.c *.h
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.
ZMODEM Command Download
cpszall:all
sz -c "c:;cd /yam/dist"
sz -ya $(YD)/*.me
sz -yqb y*.exe
sz -c "cd /yam"
sz -i "!insms"
This Makefile fragment uses sz to issue commands to
Professional-YAM to change current disk and directory.
Next, sz transfers the .me 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 conven-
tions. The third line transfers some .exe files. The
fourth and fifth lines command Pro-YAM to change directory
and execute a PC-DOS batch file insms . Since the batch file
takes considerable time, the -i form is used to allow sz to
exit immediately.
XMODEM File Transfer (To Crosstalk)
$ sx -a foo.c
ESC
rx foo.c
The above three commands transfer a single file from Unix to
a PC and Crosstalk with sz translating Unix newlines to DOS
CR/LF. This combination is much slower than ZMODEM.
SEE ALSO
rz(omen), ZMODEM.DOC, YMODEM.DOC, Professional-YAM,
IMP(CP/M), sq(omen), todos(omen), tocpm(omen), tomac(omen),
yam(omen)
Compile time options required for various operating systems
are described in the source file.
Printed 10/25/87 OMEN 4
SZ(1) UNIX Programmer's Manual SZ(1)
VMS VERSION
The VMS version does not transmit the file date. The VMS
version calculates the file length by reading the file and
counting the bytes.
The VMS version does not support YMODEM-g or ZMODEM.
When VMS is lightly loaded, the response time may be too
quick for MODEM7 unless the MODEM7 q modifier is used.
The VMS C standard i/o package and RMS sometimes interact to
modify file contents unexpectedly.
FILES
32 bit CRC code courtesy Gary S. Brown.
sz.c, rbsb.c, zm.c, zmodem.h source files
/tmp/szlog stores debugging output (sz -vv)
>Not implemented in amiga version
>TESTING FEATURE
> The command "sz -T file" exercises the Attn 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 sz is inter-
> rupted, it should send a ZDATA header followed by another
> defective packet. If the receiver does not detect five long
> data packets, the Attn sequence is not interrupting the
> sender, and the Myattn string in sz.c must be modified.
>
> After 5 packets, sz 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 gen-
> erated.
>
BUGS
Calling sz from most versions of cu(1) doesn't work because
cu's receive process fights sz for characters from the
modem.
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 (1023
bytes with XMODEM-k).
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
Printed 10/25/87 OMEN 5
SZ(1) UNIX Programmer's Manual SZ(1)
length unconditionally.
Most ZMODEM options are merely passed to the receiving pro-
gram; some do not implement all 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, sz 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. The test mode leaves
a zero length file on the receiving system.
Some high speed modems have a firmware bug that drops char-
acters when the direction of high speed transmissson is
reversed. The environment variable ZNULLS may be used to
specify the number of nulls to send before a ZDATA frame.
Values of 101 for a 4.77 mHz PC and 124 for an AT are typi-
cal.
Printed 10/25/87 OMEN 6