SZ(1)SZ(1)NAMEsz - send a file using the zmodem protocol
SYNOPSISsz [-LNbdefnopqruvy+] [-ci command] [-Ll n] [-t timeout]
OPTIONS-L # Use n-byte packets
-N # Overwrite if source is newer/longer
-b # Binary file
-c # Send command for execution
-d # Convert dot to slash in names
-e # Escape for all control characters
-f # Send full path name
-i # Send command and return immediately
-l # Flow control every n packets
-n # Overwrite destination if source is newer
-o # Use old (16-bit) checksum
-p # Protect file if it already exists
-q # Quiet; opposite of verbose
-r # Resume interrupt file transfer
-t # Set timeout in tenths of a second
-u # Unlink file after successful transmission
-v # Verbose; opposite of quiet
-y # Yes, clobber existing files
-+ # Append to an existing file
EXAMPLESsz file </dev/tty01 >/dev/tty01
# Send file
DESCRIPTION
XMODEM, YMODEM, and ZMODEM are a family of protocols that are widely
used is the MS-DOS world for transferring information reliably from one
computer to another. In all of these protocols, a series of bytes are
sent from one computer to the other, and then an acknowledgement is
sent back to confirm correct reception. Checksums are used to detect
errors so that transmission is reliable even in the face of noisy tele‐
phone lines. Sz is a program that sends a file sent from another com‐
puter using the zmodem protocol. The file can be received using rz.
Sz uses the ZMODEM error correcting protocol to send one or more files
over a dial-in serial port to a variety of programs running under MINIX
3, UNIX, MS-DOS, CP/M, VMS, and other operating systems. It is the
successor to XMODEM and YMODEM.
ZMODEM greatly simplifies file transfers compared to XMODEM. In addi‐
tion 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.
Output from another program may be piped to sz for transmission by
denoting standard input with -:
"ls -l | 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 command:
"ls -l | ONAME=con 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 convert UNIX newlines to PC-DOS
carriage returns and linefeeds. On UNIX systems, additional informa‐
tion about the file is transmitted. If the receiving program uses this
information, 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.
If sz is invoked with $SHELL set and if that variable contains 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 options and flags available are:
-+
Instruct the receiver to append transmitted data to an existing file.
-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
Binary override: transfer file without any translation.
-c
Send COMMAND (follows c) 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 MS-DOS or CP/M) is trans‐
mitted 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
Send COMMAND (follows i) to the receiver for execution, return Imme‐
diately upon the receiving program's successful reception of the com‐
mand.
-L
Use ZMODEM sub-packets of length n (follows L). A larger n (32 <= n
<= 1024) gives slightly higher throughput, a smaller one speeds error
recovery. The default is 128 below 300 baud, 256 above 300 baud, or
1024 above 2400 baud.
-l
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 lacking.
-n
Send each file if destination file does not exist. Overwrite desti‐
nation file if source file is newer than the destination file.
-N
Send each file if destination file does not exist. Overwrite desti‐
nation file if source file is newer or longer than the destination
file.
-o
Disable automatic selection of 32 bit CRC.
-p
Protect existing destination files by skipping transfer if the desti‐
nation file exists.
-q
Quiet suppresses verbosity.
-r
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
Change timeout. The timeout, in tenths of seconds, follows, the -t
flag.
-u
Unlink the file after successful transmission.
-w
Limit the transmit window size to n bytes (n follows (enw).
-v
Verbose causes a list of file names to be appended to /tmp/szlog.
-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 on the destination system.
Examples
Below are some examples of the use of sz.
"sz -a *.c
This single command transfers all .c files in the current directory
with conversion (-a) to end-of-line conventions appropriate to the
receiving environment.
"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 MINIX 3 to MS-DOS text format.
SEE ALSOrz(1), term(1).
SZ(1)
