.CD "sz \(en send a file using the zmodem protocol"
.SX "sz\fR [\fB\(enLNbdefnopqruvy+\fR]\fR [\fB\(enci \fIcommand\fR] [\fB\(enLl\fR n\fR] [\fB\(ent \fItimeout\fR]
.FL "\(enL" "Use \fIn\fR-byte packets"
.FL "\(enN" "Overwrite if source is newer/longer"
.FL "\(enb" "Binary file"
.FL "\(enc" "Send command for execution"
.FL "\(end" "Convert dot to slash in names"
.FL "\(ene" "Escape for all control characters"
.FL "\(enf" "Send full path name"
.FL "\(eni" "Send command and return immediately"
.FL "\(enl" "Flow control every \fIn\fR packets"
.FL "\(enn" "Overwrite destination if source is newer"
.FL "\(eno" "Use old (16-bit) checksum"
.FL "\(enp" "Protect file if it already exists"
.FL "\(enq" "Quiet; opposite of verbose"
.FL "\(enr" "Resume interrupt file transfer"
.FL "\(ent" "Set \fItimeout\fR in tenths of a second"
.FL "\(enu" "Unlink file after successful transmission"
.FL "\(env" "Verbose; opposite of quiet"
.FL "\(eny" "Yes, clobber existing files"
.FL "\(en+" "Append to an existing file"
.EY "sz file </dev/tty1 >/dev/tty1" "Send \fIfile\fR"
.PP
XMODEM, YMODEM, and ZMODEM are a family of protocols that are widely used
is the \s-2MS-DOS\s0 world for transferring information reliably from one
computer to another.  In all of these protocols, a series of bytes are sent
from one computer to the other, and then an acknowledgement is sent back
to confirm correct reception.  Checksums are used to detect errors so that
transmission is reliable even in the face of noisy telephone lines.
\fISz\fR is a program that sends a file sent from another computer using the
zmodem protocol.
The file can be received using \fIrz\fR.
Both are a highly complex programs.
See Chap. 9 for more information.
For an alternative, see \fIkermit\fR.