rz, rc, rx, gz man page
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rx, rc, rb, rz - Receive Files and Commands with X/Y/ZMODEM


rz [- tv]
rb [- tv]
rc [- tv] file
rx [- tv] file
gz file ...


This program uses error correcting protocols to receive files over a dial-in serial port from a variety of programs running under PC-DOS, CP/M, Unix, and other operating systems. It is invoked from a shell prompt manually, or automatically as a result of an "sz file ..." command given to the calling program.

This is a copyrighted shareware program. Commercial use of this program is subject to licensing conditions detailed in the rz.c source code. "Commercial Use" includes use of this program to receive files from commercial and/or shareware programs not published by Omen Technology INC.

This program is not designed to be called from cu(1), tip(1), or other communications programs. Unix flavors of Omen Technology's Professional-YAM communications software are available for dial-out applications. Unix Professional-YAM supports dial-out applications with telephone directory, a powerful script language with learn function, high quality multiple protocol support, and UUCP port arbitration.

Rz (Receive ZMODEM) receives one or more files with the ZMODEM 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 defective ZMODEM implementations may require starting rz manually.

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.

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 True YMODEM file information is not 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 and other historical systems.

Rc receives a single file with XMODEM-CRC or XMODEM-1k-CRC 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.

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.

Gz is a shell script which calls sz to command Pro-YAM or ZCOMM to transmit the specified files. Pathnames used with gz must be escaped if they have special significance to the Unix shell.
EXAMPLE: gz "-a C:*.c D:*.h"

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 report progress to /tmp/rzlog. The following entry works for Unix SYS III/V:
rzrmail::5:1::/bin:/usr/local/rzrmail If the SHELL environment variable includes rsh or rksh (restricted shell), rz will not accept absolute pathnames or references to a parent directory, will not modify an existing file, and removes any files received in error.

The meanings of the available options are:

t tim
Change timeout to tim tenths of seconds.

Verbose causes a list of file names to be appended to /tmp/rzlog . More v's generate more detailed debugging output. (Pro-YAM command) <ALT-2> Pro-YAM Command: sz *.h *.c (This automatically invokes rz on the connected system.)


Exit status is as follows: 0 for successful transfers. 1 if unrecoverable errors are detected. 2 if syntax errors or file access problems are detected. 3 if the program was terminated by a caught interrupt.


Professional-YAM, ZCOMM, DSZ, crc, sz, usq, undos

Compile time options required for various operating systems are described in the source file.


ZMODEM's support of XOFF/XON flow control allows proper operation in many environments that do not support XMODEM uploads. Unfortunately, not all Unix versions support input flow control. The TTY input buffering on some systems may not adequately buffer 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, but YMODEM with 128 byte blocks works properly.

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"). Although this compromises ZMODEM's throughput, ZMODEM's superior reliability remains intact.

If a program that does not properly implement the specified file transfer protocol causes rz to "hang" the port after a failed transfer, either wait for rz to time out or keyboard a dozen Ctrl-X characters. Every reported instance of this problem has been corrected by using ZCOMM, Pro-YAM, DSZ, 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.

In the case of a few poorly designed microcomputers, sending serial data to a tty port at sustained high speeds has been known to cause lockups, system halts, kernel panics, and occasional antisocial behaviour. This problem is not unique to rz; CRT terminals with block mode transmission and line noise have the same effect. When experimenting with high speed input to a system, consider rebooting the system if the file transfers are not successful, especially if the personality of the system appears altered.

The Unix "ulimit" parameter must be set high enough to permit large file transfers to Unix.

Telebit modems must not be set to "spoof" UUCP, XMODEM, or KERMIT. Setting one of these spoofing modes interferes with other protoocls.

32 bit CRC code courtesy Gary S. Brown. Directory creation code from John Gilmore's PD TAR program.


This version of rz does not support some ZMODEM features. Unix flavors of Professional-YAM may be linked to "rz" to support these features.

The ASCII option's CR/LF to NL translation merely deletes CR's; undos(omen) performs a more intelligent translation.


Rz supports ZMODEM command execution (zcommand), incoming ZMODEM binary (-b), ASCII (-a), newer(-n), newer+longer(-N), protect (-p), Crash Recovery(-r), clobber (-y), match+clobber (-Y), compression(-Z), and append (-+) requests. Other options sent by the sender are ignored. The default is protect (-p) and binary (-b).

Unix Professional-YAM provides higher performance and other features not supported by rz. Please contact Omen Technology Inc for product information.

Omen Technology INC
Post Office Box 4681
Portland OR 97208


rz.c, crctab.c, rbsb.c, zm.c, zmr.c, zmodem.h, rz.1

/tmp/rzlog stores debugging output generated with -vv option

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