fusefile \- FUSE file mount for combining file fragments
.SH SYNOPSIS
-.B fusefile \fR[fuse options\fR] \fBmountpoint\fR \fIfilename/from-to\fR ...
+.B fusefile \fR[\fIfuse-opts\fR] \fBmountpoint\fR \fR[\fIoverlay\fR] \fIfilename/from-to\fR ...
.SH DESCRIPTION
file which gets distributed accordingly to the fragments, but cannot
change size.
+An optional overlay file is declared with an
+\fB-overlay:\fIfilename\fR argument between the mount point and the
+fragments. This file is then set up as an overlay for capturing writes
+to the fused file. The overlay file will contain the written fused
+file regions, followed by meta data to distinguish between written
+content and "holes" (where content comes from the fused fragments).
+
The fragment arguments include the filename of a source file, and
optionally start and end byte positions. All in all there five
variations:
\fB$ fusefile y x/2442: x/:2442\fR
.RE
+Replace a partition in an image file with a different file
+.RS
+# Check the partition table
+.br
+\fB$ partx -oNR,START,SECTORS disk.raw\fR
+ NR START SECTORS
+ 1 2048 2097152
+ 2 2099200 409600
+ 3 2508800 14268383
+.br
+# Replace partition 2 of 409600 sectors from 2099200 with
+.br
+# the file "insert.fat" clipped to 409600 sectors.
+.br
+\fB$ fusefile -ononempty disk.raw \\
+ disk.raw/0:$(( 2099200*512 )) \\
+ insert.fat/0:$(( 409600*512 )) \\
+ disk.raw/$(( (2099200+409600)*512 )):\fR
+.RE
+
+Protect raw disk image file with an overlay:
+.RS
+\fB$ fusefile -ononempty disk.raw -overlay:today disk.raw\fR
+.RE
+By that set up, the overlay file, "today", will protect the disk image
+file, "disk.raw" from changes, and also override the pathname
+"disk.raw" to be the fused file.
+
.SH NOTES
Note that \fBfusefile\fR opens the nominated source file or files
If a source file changes the fused file will present the new content.
If a source is reduced in size, access will be inconsistent.
-If the mountpoint file doesn't exist, then \fBfusefile\fR creates it,
-and removes it when unmounted.
+If the mountpoint file doesn't exist, then \fBfusefile\fR creates it.
+Unmounting is done with "\fBfusermount -u\fR \fImountpoint\fR" as
+usual.
+
+Using an overlay file makes the fused file writable regardless of the
+fused fragments with the overlay file containing any changes to the
+original. The overlay file is reusable for subsequent fusing of the
+same fragments for reconstructing a prior session with changes.
.SH AUTHOR
-Ralph Rönnquist <ralph.ronnquist@gmail.com>
+Ralph Rönnquist <ralph.ronnquist@gmail.com>.
+