H.3. Summary of rz and sz Options
Because of the prevailing poor state of RZSZ documentation in the
standard Linux distributions and because RZSZ tools don't have
interactive help, we're providing you with summaries of the important
flags for using the Zmodem protocol for file transfer. However, you
should get the manual pages and possibly other documentation you need
from an FTP site or a BBS; see
the earlier section "Section H.1, "Getting RZSZ"." When you use RZSZ on
another system, you should be aware that the utilities may have been
modified to support additional features or to disable standard
features. Check the local documentation.
The rz utility recognizes the following flags:
Appends to any existing file of the same name, rather than
overwrite it. (This can cause a malformed file if
you are retransmitting an interrupted Zmodem transfer.)
Receives ASCII text and converts files to Unix newline conventions,
stripping carriage returns and all characters beginning with
a Ctrl-Z (the end-of-file character for the CP/M OS).
Receives binary and saves the file in exactly the form it was received.
Discards output. It sends data to /dev/null; this is useful for tests.
Escapes the control characters. By default, sz
escapes XON, XOFF, and (in
older versions) DLE. This option
forces the sending Zmodem program to escape others as well.
Protects destination files. This option skips Zmodem transfer if
a destination file of the same name already exists. (Be aware that this
prevents completion of an interrupted Zmodem transfer.)
Quiet exchange. Suppresses informational messages to standard output.
- -t n
Changes timeout to n tenths of seconds.
Turns on verbose. Not like a typical Unix utility "verbose." This flag
causes a list of transferred filenames to be appended to a log
file, normally /tmp/rzlog. If multiple -v flags are
used, additional information is also stored to the log.
Now for sz.
Most sz options are simply passed to the receiving
program that performs the operation. Not all Zmodem receiving
programs can execute the requested options.
If sz is invoked with the $SHELL environment variable set
to a restricted shell (e.g., rsh),
sz restricts pathnames to the current directory and to the
value of the $PUBDIR variable if set (often used with UUCP),
as well as subdirectories of these directories.
The meanings of the most common sz options are:
Has the Zmodem receiver utility append the transmitted
data to an existing file.
Sends ASCII text and converts each newline character
(Unix style) in the transmitted file to a carriage
return/linefeed (DOS style).
Transfers the file without any translation and
tells the receiving Zmodem program not to make any translation. This option is used for binary sites.
Diverts path and compensates for filename and
pathname incompatibilities between systems. (It's more reliable to rename
files before you send them, though.)
All periods (.) in a filename are changed to path-subpath
separators in the transmitted
pathname. (In Unix, change to /
characters, and in DOS,
change to backslashes. A file named foobar.bazbuzzy, for
example, is transmitted as foobar/bazbuzzy.) If a
stem filename has more than eight characters, a period is inserted
to allow up to 11 characters. For example, a Unix file named
foo.barbazbuzzy would be transmitted as foo/barbazbuzzy,
but when received by the DOS Zmodem program would be stored as
foo\barbazbu.zzy. (If the file is longer than that, and the
receiving program cannot handle the length, the file is truncated at
the limit--depending on the "wisdom" of the
DOS Zmodem program.)
Escapes control characters.
Preserves full path. Directory prefixes are usually omitted; this forces
the entire path to be sent in the transmitted filename.
- -L bytes
Sets the Zmodem subpacket length in bytes. (These are not the same as
Xmodem, Ymodem, or Kermit packets.) The
default packet length is 128 below 300 baud, 256 above 300 baud,
or 1024 above 2400 baud. A larger packet gives slightly higher
throughput, while a smaller packet speeds error recovery. This isn't worth
messing with for modern modems that implement an error-correcting
protocol in hardware.
- -l num
Sets the packet length in bytes. The receiver acknowledges correct data every
num characters, where num is a value between 32 and 1024.
You can use this to avoid overrun when XOFF flow control is
lacking between the systems.
Newer file preservation. Send the file if the destination file of the
same name does not exist, and overwrite the destination file only if
the source file is newer than the destination file.
Newer/longer file preservation. Send the file if the destination
file of the same name does not exist, and overwrite the destination file
only if the source file is newer or longer than the destination file.
Protects destination files. Doesn't transfer the file if the destination
Suppresses reporting to the standard error.
Resumes an interrupted file transfer. If the source file
is longer than
the destination file, the transfer begins at the offset in the
source file that equals the length of the destination file. (This mode
is automatically assumed in some Zmodem receiving programs.)
- -t num
Timeout. Set the timeout to num
tenths of seconds.
Breaks file links after successful transmission. Conveniently
implements a way to "collect" files to a directory they can all be sent from.
- -w bytes
Limits the transmit window size to the specified number
of bytes to impose flow control and limit buffering.
Turns on verbose. Appends the list of transmitted filenames to
the /tmp/szlog record. Extra -v options cause
additional information about the transfer to be added to the record.
Tells the receiving Zmodem program to overwrite any
existing files having the same name.
Tells the receiving Zmodem program to
overwrite any existing file with the same name, but skip sending
source files that have a file with the same pathname
on the destination system.
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