Syntax and Parameters 5-13
2325A137REFGD Revision B 2325 Reference Guide
O#
Overwrite Existing File(s)
The O option specifies what action the receiver should take if the file
being transferred already exists on the receiver’s side. When using this
option, replace the # symbol with the desired setting:
1 - Overwrite if source is longer or newer
2 - Overwrite if CRCs don’t match
3 - Append to existing file
4 - Always overwrite
5 - Overwrite if source is newer
6 - Overwrite if dates or lengths don’t match
7 - Never overwrite
By default, XFER operates in O7 mode—existing files are never
overwritten. For Xmodem, the only valid options are O4 and O7; all
other settings resolve to O7 (never overwrite). All settings for the O
option are available with Zmodem protocol.
To remain compatible with previous versions of XFER, the O option
used without a setting resolves to the O4 setting (always overwrite). This
differs from most other XFER options, where specifying the option
without a setting usually resolves to the default condition for that option.
To use the default condition for the O option, you must specify the O7
setting.
An invalid setting will result in an error on the command line.
Note: XFER does not prompt you to specify whether a file should be
overwritten in the default mode. If no overwrite option is
specified, the file will never be overwritten. Under Xmodem,
the session will abort. Under Zmodem, the file will be skipped
and the next file will be transferred.
For the O6 setting under Zmodem, XFER does not set the date or time of
a received file to match the original date or time of the sender’s version
of the file. Instead, the date and time are taken from the receiver’s
operating system when the file is received and created. Because of this,
it is highly unlikely that a file transferred with XFER will have the exact
date of the original file. Since the resolution of times for files under DOS
is in two-second increments, it is unlikely the timestamps will be the
same, even if the times on the receiver and sender are calibrated
frequently. Also, DOS doesn’t report the seconds field when displaying
the modification time of a file during a file listing. So, two files may
appear to have the same timestamp when in fact they don’t. The
