lsz.1

支持X/Y/Z Modem协议的传输文件的通讯程序

Use this option with care.
.TP
.B "-p, --protect"
(ZMODEM) Protect existing destination files by skipping transfer if the
destination file exists.
.TP
.B "-q, --quiet"
Quiet suppresses verbosity.
.TP
.B "-R, --restricted"
Restricted mode: restricts pathnames to the current directory and
PUBDIR (usually /usr/spool/uucppublic) and/or subdirectories
thereof.
.TP
.B "-r, --resume"
(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.
.TP
.B "-s HH:MM, --stop-at HH:MM"
Stop transmission at
.B HH 
hours, 
.B MM
minutes. Another variant, using 
.B +N 
instead of 
.B HH:MM,
stops transmission in
.B N
seconds.
.TP
.B "-S, --timesync"
enable timesync protocol support. See timesync.doc for further 
information.

This option is incompatible with standard zmodem. Use it with care.
.TP
.B "--syslog[=off]"
turn syslogging on or off. the default is set at configure time.
This option is ignored if no syslog support is compiled in.
.TP
.B "-t TIM, --timeout TIM"
Change timeout to
.I TIM
tenths of seconds.
.TP
.B "-T, --turbo"
Do not escape certain characters (^P, ^P|0x80, telenet escape sequence
[CR + @]). This improves performance by about 1 percent and shouldn't
hurt in the normal case (but be careful - ^P might be useful if connected
through a terminal server).
.TP
.B "-u"
Unlink the file after successful transmission.
.TP
.B "-U, --unrestrict"
Turn off restricted mode (this is not possible if running under a 
restricted shell).
.TP
.B "-w N, --windowsize N"
Limit the transmit window size to N bytes (ZMODEM).
.TP
.B "-v, --verbose"
Verbose output to stderr. More v's generate more output.
.TP
.B "-X, --xmodem"
use XMODEM protocol.
.TP
.B "-y, --overwrite"
Instruct a ZMODEM receiving program to overwrite any existing file
with the same name.
.TP
.B "-Y, --overwrite-or-skip"
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.
.TP
.B "--ymodem"
use ZMODEM protocol.
.TP
.B "-Z, --zmodem"
use ZMODEM protocol.
.PD
.SH SECURITY
Restricted mode restricts pathnames to the current directory
and PUBDIR (usually /var/spool/uucppublic)
and/or subdirectories thereof, and disables remote command
execution.

Restricted mode is entered if the 
.B R
option is given or if lsz detects that it runs under a restricted
shell or if the environment variable ZMODEM_RESTRICTED is found.

Restricted mode can be turned of with the 
.B U
option if not running under a restricted shell.

.SH ENVIRONMENT
.TP
.B ZNULLS
may be used to specify the number of nulls to send before a ZDATA frame.
.TP
.B SHELL
lsz recognizes a restricted shell if this variable includes
.I "rsh"
or
.I "rksh"
.TP
.B ZMODEM_RESTRICTED
lrz enters restricted mode if the variable is set.
.TP
.B TMPDIR
If this environment variable is set its content is used as the 
directory to place in the answer file to a 
.B timesync 
request.
.B TMP
Used instead of TMPDIR if TMPDIR is not set. If neither TMPDIR nor
TMP is set /tmp will be used.
.SH EXAMPLES
.ne 7
.B "ZMODEM File Transfer"
(Unix to DSZ/ZCOMM/Professional-YAM)
.br
.B "% sz \-a *.c"
.br
This single command transfers all .c files in the current Unix directory
with conversion
.RB ( \-a )
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.

.br
.B "% sz \-Yan *.c *.h"
.br
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.
.br
.B
$ sz -\\Yan file1.c file2.c file3.c foo.h baz.h
.R
(for VMS)
.br

.B "ZMODEM Command Download"
(Unix to Professional-YAM)
.br
 cpszall:all
    sz \-c "c:;cd /yam/dist"
    sz \-ya $(YD)/*.me
    sz \-yqb y*.exe
    sz \-c "cd /yam"
    sz \-i "!insms"
.br
This Makefile fragment uses
.B sz
to issue commands to Professional-YAM to change current disk and directory.
Next,
.B sz
transfers the
.I .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 conventions.
The third line transfers some
.I .exe
files.
The fourth and fifth lines command Pro-YAM to
change directory and execute a PC-DOS batch file
.I insms .
Since the batch file takes considerable time, the
.B "\-i"
form is used to allow
.B sz
to exit immediately.

.B "XMODEM File Transfer"
(Unix to Crosstalk)
.br
%
.B "sx \-a foo.c"
.br
.B "ESC"
.br
.B "rx foo.c"
.br
The above three commands transfer a single file
from Unix to a PC and Crosstalk with
.I sz
translating Unix newlines to DOS CR/LF.
This combination is much slower and far less reliable than ZMODEM.
.SH ERROR MESSAGES
"Caught signal 99"
indicates the program was not properly compiled,
refer to "bibi(99)" in rbsb.c for details.
.SH SEE ALSO
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.
.SH "VMS VERSION"
The VMS version does not support wild cards.
Because of VMS DCL, upper case option letters muse be represented
by \\ proceding the letter.

The current VMS version does not support XMODEM, XMODEM-1k, or YMODEM.

VMS C Standard I/O and RMS may interact to modify the file contents.
.SH FILES
32 bit CRC code courtesy Gary S. Brown.

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

sz.c, crctab.c, vrzsz.c, zm.c, zmodem.h, vmodem.h, vvmodem.c,
VMS source files.

/tmp/szlog stores debugging output (sz -vv)
(szlog on VMS).
.SH "TESTING FEATURE"
The command "sz -T file"
exercises the
.B 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
.B sz
is interrupted,
it should send a ZDATA header followed by another defective packet.
If the receiver does not detect five long data packets,
the
.B Attn
sequence is not interrupting the sender, and the
.B Myattn
string in
.B sz.c
must be modified.

After 5 packets,
.B 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 generated.
.SH BUGS
Calling
.I sz
from most versions of cu(1) doesn't work because cu's receive process
fights
.I sz
for characters from the modem.

On at least one BSD system, sz would hang or exit when 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.

Programs that do not properly implement the specified file transfer protocol
may cause
.I sz
to "hang" the port for a minute or two.
This problem is corrected by using
ZCOMM, Pro-YAM, 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 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,
.B 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.

A few high speed modems have a firmware bug that drops characters 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 typical.