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rx, rb, rz - XMODEM, YMODEM, ZMODEM (Batch) file receive
While rz is smart enough to be called from cu(1), very few versions of cu(1) are smart enough to allow rz to work properly. Unix flavors of Professional-YAM are available for such dial-out application.
Rz (Receive ZMODEM) receives files with the ZMODEM batch protocol. Pathnames are supplied by the sending program, and directories are made if necessary (and possible). Normally, the "rz" command is automatically issued by the calling ZMODEM program, but some defective ZMODEM implementations may require starting rz the old fashioned way.
Rb receives file(s) with YMODEM, accepting either standard 128 byte sectors or 1024 byte sectors (YAM sb -k option). The user should determine when the 1024 byte block length actually improves throughput without causing lost data or even system crashes.
If True YMODEM (Omen Technology trademark) file information (file length, etc.) is received, the file length controls the number of bytes written to the output dataset, and the modify time and file mode (iff non zero) are set accordingly.
If no True YMODEM file information is received, slashes in the pathname are changed to underscore, and any trailing period in the pathname is eliminated. This conversion is useful for files received from CP/M systems. With YMODEM, each file name is converted to lower case unless it contains one or more lower case letters.
Rx receives a single file with XMODEM or XMODEM-1k protocol. The user should determine when the 1024 byte block length actually improves throughput without causing problems. The user must supply the file name to both sending and receiving programs. Up to 1023 garbage characters may be added to the received file.
Rz may be invoked as rzCOMMAND (with an optional leading - as generated by login(1)). For each received file, rz will pipe the file to ``COMMAND filename'' where filename is the name of the transmitted file with the file contents as standard input.
Each file transfer is acknowledged when COMMAND exits with 0 status. A non zero exit status terminates transfers.
A typical use for this form is rzrmail which calls rmail(1) to post mail to the user specified by the transmitted file name. For example, sending the file "caf" from a PC-DOS system to rzrmail on a Unix system would result in the contents of the DOS file "caf" being mailed to user "caf".
On some Unix systems, the login directory must contain a link to COMMAND as login sets SHELL=rsh which disallows absolute pathnames. If invoked with a leading ``v'', rz will be verbose (see v option). The following entry works for Unix SYS III/V:
If rz 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.
Use this option with care.
This option is ignored and a warning is printed if your systems doesn't support O_SYNC.
See SECURITY for mode information about restricted mode.
Lrz tries to set the local system time to the remote time if this option is given twice (this fails if lrz is not run by root).
This option makes lrz incompatible with certain other ZModems. Don't use it unless you know what you are doing.
See --tcp-server for more information.
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 program 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.
To use a more restricted mode set the environment variable ZMODEM_RESTRICTED or give the R option. This disables creation of subdirectories and invisible files.
Restricted mode may be turned off with the U option, unless lrz runs under a restricted shell.
Compile time options required for various operating systems are described in the source file.
The Unix "ulimit" parameter must be set high enough to permit large file transfers.
The TTY input buffering on some systems may not allow long blocks or streaming input at high speed. You should suspect this problem when you can't send data to the Unix system at high speeds using ZMODEM, YMODEM-1k or XMODEM-1k, when YMODEM with 128 byte blocks works properly. If the system's tty line handling is really broken, the serial port or the entire system may not survive the onslaught of long bursts of high speed data.
The DSZ or Pro-YAM zmodem l numeric parameter may be set to a value between 64 and 1024 to limit the burst length ("zmodem pl128").
32 bit CRC code courtesy Gary S. Brown. Directory creation code from John Gilmore's PD TAR program.
Programs that do not properly implement the specified file transfer protocol may cause sz to "hang" the port for a minute or two. Every reported instance of this problem has been 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.
Pathnames are restricted to 127 characters. In XMODEM single file mode, the pathname given on the command line is still processed as described above. The ASCII option's CR/LF to NL translation merely deletes CR's; undos(omen) performs a more intelligent translation.
VMS C Standard I/O and RMS may interact to modify file contents unexpectedly.
The VMS version does not support invocation as rzCOMMAND . The current VMS version does not support XMODEM, XMODEM-1k, or YMODEM.
According to the VMS documentation, the buffered input routine used on the VMS version of rz introduces a delay of up to one second for each protocol transaction. This delay may be significant for very short files. Removing the "#define BUFREAD" line from rz.c will eliminate this delay at the expense of increased CPU utilization.
The VMS version causes DCL to generate a random off the wall error message under some error conditions; this is a result of the incompatibility of the VMS "exit" function with the Unix/MSDOS standard.
The Unix versions support ZMODEM command execution.
rz.c, crctab.c, vrzsz.c, zm.c, zmodem.h, vmodem.h, vvmodem.c, VMS source files.
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