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SZ(1)                                                                    SZ(1)



NAME
       sx, sb, sz - XMODEM, YMODEM, ZMODEM file send

SYNOPSIS
       sz [-+8abdefkLlNnopqTtuvyY] file ...
       sb [-adfkqtuv] file ...
       sx [-akqtuv] file
       sz [-oqtv] -c COMMAND
       sz [-oqtv] -i COMMAND
       sz -TT

DESCRIPTION
       Sz  uses the ZMODEM, YMODEM or XMODEM error correcting protocol to send one or more files over a dial-in serial
       port to a variety of programs running under PC-DOS, CP/M, Unix, VMS, and other operating systems.

       While rz is smart enough to be called from cu(1), very few versions of cu(1) are smart enough to  allow  sz  to
       work properly.  Unix flavors of Professional-YAM are available for such dial-out application.


       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 inter-
       vention), Display of individual and total file lengths and transmission time estimates, Crash Recovery,  selec-
       tive file transfers, and preservation of exact file date and length.

       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 Unix 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.


       Sb batch sends one or more files with YMODEM or ZMODEM protocol.  The  initial  ZMODEM  initialization  is  not
       sent.   When requested by the receiver, sb supports YMODEM-g with "cbreak" tty mode, XON/XOFF flow 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 acknowledging each transmitted sector.

       On  Unix  systems,  additional  information  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.


       Sx  sends  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.

       If sz is invoked with $SHELL set and iff that variable contains the string rsh  ,  rbash  or  rksh  (restricted
       shell),  sz operates in restricted mode.  Restricted mode restricts pathnames to the current directory and PUB-
       DIR (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.


       The sixth form (sz -TT) attempts to output all 256 code combinations to the terminal.  In you are having diffi-
       culty sending files, this command lets you see which character codes are being eaten by the operating system.


       If  sz  is  invoked  with  stdout and stderr to different datasets, Verbose is set to 2, causing frame by frame
       progress reports to stderr.  This may be disabled with the q option.

       The meanings of the available options are:

       -+, --append
              Instruct the receiver to append transmitted data to an existing file (ZMODEM only).
       -2, --twostop
              use two stop bits (if possible). Do not use this unless you know what you are doing.
       -8, --try-8k
              Try to go up to 8KB blocksize. This is incompatible with standard zmodem, but a common extension in  the
              bbs world. (ZMODEM only).
       --start-8k
              Start with 8KB blocksize. Like --try-8k.
       -a, --ascii
              Convert  NL characters in the transmitted file to CR/LF.  This is done by the sender for XMODEM and YMO-
              DEM, by the receiver for ZMODEM.
       -b, --binary
              (ZMODEM) Binary override: transfer file without any translation.
       -B NUMBER, --bufsize NUMBER
              Use a readbuffer of NUMBER bytes. Default ist 16384, which should be enough for most situations. If  you
              have  a  slow  machine  or a bad disk interface or suffer from other hardware problems you might want to
              increase the buffersize.  -1 or auto use a buffer large enough to buffer the whole file. Be careful with
              this option - things normally get worse, not better, if the machine starts to swap.

              Using this option turns of memory mapping of the input file. This increases memory and cpu usage.
       -c COMMAND, --command COMMAND
              Send COMMAND to the receiver for execution, return with COMMAND?s exit status.
       -C N, --command-tries N
              Retry to send command N times (default: 11).
       -d, --dot-to-slash
              Change  all  instances of "." to "/" in the transmitted pathname.  Thus, C.omenB0000 (which is unaccept-
              able to MSDOS or CP/M) is transmitted as C/omenB0000.  If the resultant filename has more than 8 charac-
              ters in the stem, a "." is inserted to allow a total of eleven.

              This option enables the --full-path option.
       --delay-startup N
              Wait N seconds before doing anything.
       -e, --escape
              Escape all control characters; normally XON, XOFF, DLE, CR-@-CR, and Ctrl-X are escaped.
       Force the sender to rename the new file if a file with the same
              name already exists.
       -f, --full-path
              Send Full pathname.  Normally directory prefixes are stripped from the transmitted filename.

              This is also turned on with to --dot-to-slash option.
       -h, --help
              give help.
       -i COMMAND, --immediate-command COMMAND
              Send  COMMAND  to the receiver for execution, return immediately upon the receiving program's successful
              recption of the command.
       -k, --1k
              (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.  (ZMODEM streams the data for the best possible through-
              put.)
       -L N, --packetlen 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.
       -m N, --min-bps N
              Stop transmission if BPS-Rate (Bytes Per Second) falls below N for a certain  time  (see  --min-bps-time
              option).
       -M N, --min-bps-time
              Used together with --min-bps. Default is 120 (seconds).
       -l N, --framelen 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 lacking.
       -n, --newer
              (ZMODEM) Send each file if destination file does not exist.  Overwrite destination file if  source  file
              is newer than the destination file.
       -N, --newer-or-longer
              (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, --16-bit-crc
              (ZMODEM) Disable automatic selection of 32 bit CRC.
       -O, --disable-timeouts
              Disable read timeout handling. This makes lsz  hang  if  the  other  side  doesn't  send  anything,  but
              increases  performance  (not much) and decreases system load (reduces number of system calls by about 50
              percent).

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

              This option is incompatible with standard zmodem. Use it with care.
       --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.
       -t TIM, --timeout TIM
              Change timeout to TIM tenths of seconds.
       -T, --turbo
              Do not escape certain characters (^P, ^P|0x80, telenet escape sequence [CR + @]). This improves  perfor-
              mance  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).
       --tcp  Try to initiate a TCP/IP connection. lsz will ask the receiving zmodem to open a TCP/IP connection.  All
              handshaking (which address / port to use) will be done by the zmodem programs.

              You  will  normally not want to use this option as lrzsz is the only zmodem which understands what to do
              (private extension). You might want to use this option if the two  programs  are  connected  (stdin/out)
              over a slow or bad (not 8bit clean) network connection.

              Use  of  this  option  imposes  a security risk, somebody else could connect to the port in between. See
              SECURITY for details.
       --tcp-client ADDRESS:PORT
              Act as a tcp/ip client: Connect to the given port.

              See --tcp-server for more information.

       --tcp-server
              Act as a server: Open a socket, print out what to do, wait for connection.

              You will normally not want to use this option as lrzsz is the only zmodem which understands what  to  do
              (private  extension).  You might want to use this if you have to use zmodem (for which reason whatever),
              and cannot use the --tcp option of lsz (perhaps because your telnet doesn't allow to spawn a local  pro-
              gram with stdin/stdout connected to the remote side).

              If  you use this option you have to start lsz with the --tcp-client ADDRESS:PORT option.  lrz will print
              the address and port on startup.

              Use of this option imposes a security risk, somebody else could connect to  the  port  in  between.  See
              SECURITY for details.

       -u     Unlink the file after successful transmission.
       -U, --unrestrict
              Turn off restricted mode (this is not possible if running under a restricted shell).
       -w N, --windowsize N
              Limit the transmit window size to N bytes (ZMODEM).
       -v, --verbose
              Verbose output to stderr. More v's generate more output.
       -X, --xmodem
              use XMODEM protocol.
       -y, --overwrite
              Instruct a ZMODEM receiving program to overwrite any existing file with the same name.
       -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.
       --ymodem
              use ZMODEM protocol.
       -Z, --zmodem
              use ZMODEM protocol.

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 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 U option if not running under a restricted shell.


       Use of the
              --tcp-client or --tcp-server options imposes a security risk, as somebody else could connect to the port
              before  you do it, and grab your data. If there's strong demand for a more secure mode i might introduce
              some sort of password challenge.



ENVIRONMENT
       ZNULLS may be used to specify the number of nulls to send before a ZDATA frame.

       SHELL  lsz recognizes a restricted shell if this variable includes rsh or rksh

       ZMODEM_RESTRICTED
              lrz enters restricted mode if the variable is set.

       TMPDIR If this environment variable is set its content is used as the directory to place in the answer file  to
              a  timesync  request.  TMP Used instead of TMPDIR if TMPDIR is not set. If neither TMPDIR nor TMP is set
              /tmp will be used.

EXAMPLES
       ZMODEM File Transfer (Unix to DSZ/ZCOMM/Professional-YAM)
       % sz -a *.c
       This single command transfers all .c files in the current Unix directory with conversion (-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.

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

       ZMODEM Command Download (Unix to Professional-YAM)
        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 conventions.  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 (Unix 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 new-
       lines to DOS CR/LF.  This combination is much slower and far less reliable than ZMODEM.

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

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.

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.

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).

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  interrupted,  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 dif-
       ference between Tcount and 5120 represents the number of characters stored in various  buffers  when  the  Attn
       sequence is generated.

BUGS
       Calling  sz from most versions of cu(1) doesn't work because cu's receive process fights 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 rou-
       tines.

       Programs that do not properly implement the specified file transfer protocol may cause 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 imple-
       mentation 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  cor-
       rect length; this may cause problems with source files that grow during the course of the transfer.  This prob-
       lem 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, 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.



lrzsz-0.12b                        2.6.1996                              SZ(1)