libisoburn/xorriso/xorriso.1

.\"                                      Hey, EMACS: -*- nroff -*-
.\" First parameter, NAME, should be all caps
.\" Second parameter, SECTION, should be 1-8, maybe w/ subsection
.\" other parameters are allowed: see man(7), man(1)
.TH XORRISO 1 "Jun, 14, 2008"
.\" Please adjust this date whenever revising the manpage.
.\"
.\" Some roff macros, for reference:
.\" .nh        disable hyphenation
.\" .hy        enable hyphenation
.\" .ad l      left justify
.\" .ad b      justify to both left and right margins
.\" .nf        disable filling
.\" .fi        enable filling
.\" .br        insert line break
.\" .sp <n>    insert n+1 empty lines
.\" for manpage-specific macros, see man(7)
.nh
.SH NAME
xorriso - creates, loads, manipulates and writes ISO 9660 filesystem images
with Rock Ridge extensions.
.SH SYNOPSIS
.B xorriso
.RI [ settings | actions ]
.br
.SH DESCRIPTION
.PP
.B xorriso
is a program which maps file objects from POSIX compliant
filesystems into Rock Ridge enhanced ISO 9660 filesystems and allows
session-wise manipulation of such filesystems. It can load the management
information of existing ISO images and it writes the session results to
optical media or to filesystem objects.
.br
Vice versa xorriso is able to restore file objects from ISO 9660 filesystems.
.PP
A special property of xorriso is that it needs neither an external ISO 9660
formatter program nor an external burn program for CD or DVD but rather
incorporates the libraries of libburnia-project.org .
.SS
.B Overview of features:
.br
Operates on an existing ISO image or creates a new one.
.br
Copies files from filesystem into the ISO image.
.br
Renames or deletes file objects in the ISO image.
.br
Changes file properties in the ISO image.
.br
Updates ISO subtrees incrementally to match given disk subtrees.
.br
Can write result as completely new image to optical media or
filesystem objects.
.br
Can write result as add-on session to appendable multi-session media, 
to overwriteable media, to regular files, and to block devices.
.br
Can restore files from ISO image to disk filesystem (see osirrox).
.br
Scans for optical drives, blanks re-useable optical media.
.br
Reads its instructions from command line arguments, dialog, and batch files.
.br
Provides navigation commands for interactive ISO image manipulation.
.br
Adjustable thresholds for abort, exit value, and problem reporting.
.SS
.B General information paragraphs:
.br
Session model
.br
Media types and states
.br
Creating, Growing, Modifying
.br
Libburn drives
.br
Rock Ridge, POSIX, X/Open
.br
Command processing
.br
Dialog, Readline, Result pager
.sp 1
Maybe you first want to have a look at section EXAMPLES near the end of
this text before reading the next few hundred lines of background information.
.SS
.B Session model:
.br
Unlike other filesystems, ISO 9660 is not intended for read-write operation but
rather for being generated in a single sweep and being written to media as a
.B session.
.br
The data content of the session is called filesystem
.B image.
.PP
The written image in its session can then be mounted by the operating system
for being used read-only. Linux is able to mount ISO images from block devices,
which may represent optical media, other media or via a loop device even
from regular disk files.
.PP
This session usage model has been extended on CD media by the concept of
.B multi-session ,
which allows to add information to the CD and gives the mount programs
of the operating systems the addresses of the entry points of each
session. The mount programs recognize block devices which represent
CD media and will by default mount the image in the last session.
.br
This session usually contains an updated directory tree for the whole media
which governs the data contents in all recorded sessions.
So in the view of the mount program all sessions of a particular media
together form a single filesystem image.
.br
Adding a session to an existing ISO image is in this text referred as
\fBgrowing\fR.
.br
The multi-session model of the MMC standard does not apply to all media
types. But program growisofs by Andy Polyakov showed how to extend this
functionality to overwriteable media or disk files which carry valid ISO 9660
filesystems. This expansion method is referred as emulated growing.
.PP
xorriso provides both ways of growing as well as an own method named
\fBmodifying\fR which produces a completely new ISO image from the old
one and the modifications. See paragraph Creating, Growing, Modifying below.
.PP
xorriso adopts the concept of multi-session by loading an eventual image
directory tree, allowing to manipulate it by several actions, and to write
the new image to the target media.
.br
The first session of a xorriso run begins by the definition of the input
drive with the eventual ISO image or by the definition of an output drive.
The session ends by command -commit which triggers writing. A -commit is
done automatically when the program ends regularly.
.PP
After -commit a new session begins with the freshly written one as input.
A new input drive can only be chosen as long as the loaded ISO image was
not altered. Pending alteration can be revoked by command -rollback.
.PP
Writing a session to the target is supposed to be very expensive in terms of
time and of consumed space on appendable or write-once media. Therefore all
intended manipulations of a particular ISO image should be done in a single
session.
.br
In some special situations (e.g. in a file-to-file situation) it can be
useful to store intermediate states and to continue with image manipulations.
.SS
.B Media types and states:
There are two families of media in the MMC standard:
.br
\fBMulti-session\fR media are CD-R, CD-RW, DVD-R, DVD+R, DVD+R/DL, and
unformatted DVD-RW. These media provide a table of content which
describes their existing sessions. See option \fB-toc\fR.
.br
\fBOverwriteable\fR media are DVD-RAM, DVD+RW, BD-RE, and formatted DVD-RW.
They allow random write access but do not provide information about their
session history. If they contain one or more ISO 9660 sessions and if the
first session was written by xorriso, then a table of content can
be emulated. Else only a single overall session will be visible.
.br
DVD-RW media can be formatted by -format full. 
They can be made unformatted by -blank deformat.
.br
Emulated drives are handled as overwriteable media if they are random
read-write accessible. If they are only sequentially writeable then
they are handled as blank multi-session media.
.PP
These media can assume several states in which they offer different
capabilities.
.br
\fBBlank\fR media can be written from scratch. They contain no ISO image
suitable for xorriso.
.br
Blank is the state of newly purchased optical media.
With used CD-RW and DVD-RW it can be achieved by action -blank "as_needed".
Overwriteable media are considered blank unless they contain an ISO image
suitable for xorriso. Action -blank "as_needed" can be used to invalidate the
image on overwriteable media, or to apply eventual mandatory formatting.
.br
\fBAppendable\fR media accept further sessions. Either they are MMC
multi-session media in appendable state, or they are overwriteable media
which contain an ISO image suitable for xorriso.
.br
Appendable is the state after writing a session with option -close off.
.br
\fBClosed\fR media cannot be written. They may contain an ISO image suitable
for xorriso.
.br
Closed is the state of DVD-ROM media and of multi-session media which were
written with option -close on. If the drive is read-only hardware then it will
probably show any media as closed CD-ROM resp. DVD-ROM.
.br
Overwriteable media assume this state in such read-only drives or if they
contain unrecognizable data in the first 32 data blocks.
.br
\fBRead-only\fR drives may or may not show session histories of multi-session
media. Often only the first and the last session are visible. Sometimes
not even that. Option -rom_toc_scan might or might not help in such cases.
.SS
.B Creating, Growing, Modifying:
.br
A new empty ISO image gets \fBcreated\fR
if there is no input drive with a valid
ISO 9660 image plus Rock Ridge extensions when the first time an output drive
is defined. This is achieved by option -dev on blank media or by option -outdev
on media in any state.
.br
The new empty image can be populated with directories and files.
Before it can be written, the media in the output drive must get into
blank state if it was not blank already.
.PP
If there is a input drive with a valid ISO image, then this image gets loaded
as foundation for manipulations and extension. The constellation of input
and output drive determines which of two write methods will be used.
They have quite different capabilities and constraints.
.PP
The method of \fBgrowing\fR adds new data to the existing media. These
data comprise of eventual new file content and they override the existing
ISO 9660 + Rock Ridge directory tree. It is possible to hide files from
previous sessions but they still exist on media and with many types of
optical media it is quite easy to recover them by mounting older sessions.
.br
Growing is achieved by option -dev.
.PP
The write method of \fBmodifying\fR produces compact filesystem
images with no outdated files or directory trees. Modifying can write its
images to target media which are completely unsuitable for multi-session
operations. E.g. DVD-RW which were treated with -blank deformat_quickest,
named pipes, character devices, sockets.
On the other hand modified sessions cannot be written to appendable media
but to blank media only.
.br
Modifying takes place whenever input drive and output drive are not the same.
This is achieved by options -indev and -outdev.
.br
So for this method one needs either two optical drives or has to work with
filesystem objects as source and/or target media.
.SS
.B Libburn drives:
.br
Input drive, i.e. source of an existing or empty ISO image, can be any random
access readable libburn drive: optical media with readable data,
blank optical media, regular files, block devices.
.br
Rock Ridge info must be present in existing ISO images and it will be generated
by the program unconditionally.
.PP
Output drive, i.e. target for writing, can be any libburn drive.
Some drive types do not support the method of growing but only the method
of modifying. They all are suitable for newly created images.
.br
All drive file objects have to offer rw-permission to the user of xorriso.
Even those which will not be useable for reading an ISO image.
.PP
MMC compliant (i.e. optical) drives on Linux usually get addressed by
the path of their block device or of their generic character device. E.g.
.br
  -dev /dev/sr0
.br
  -dev /dev/hdc
.br
  -dev /dev/sg2
.br
Get a list of accessible drives by command
.br
  -devices
.br
It might be necessary to do this as
.B superuser
in order to see all drives and to then allow rw-access for the intended users.
Consider to bundle the authorized users in a group like old "floppy".
.PP
Filesystem objects of nearly any type can be addressed by prefix "stdio:" and
their path in the filesystem. E.g.:
.br
  -dev stdio:/tmp/pseudo_drive
.br
If path leads to a regular file or to a block device then the emulated drive
is random access readable and can be used for the method of growing if it
already contains a valid ISO 9660 image. Any other file type is not readable
via "stdio:" and can only be used as target for the method of modifying.
Non existing paths in existing directories are handled as empty regular files.
.PP
A very special kind of pseudo drive are open file descriptors. They are
depicted by "stdio:/dev/fd/" and descriptor number (see man 2 open).
.br
Addresses "-" or "stdio:/dev/fd/1" depict standard output, which normally is
the output channel for result texts.
To prevent a fatal intermingling of ISO image and text messages, all result
texts get redirected to stderr if -*dev "-" or "stdio:/dev/fd/1" is among
the start arguments of the program.
.br
Standard output is currently suitable for creating a single new session
per program run without dialog. Use in other situations is discouraged
and several restrictions apply: 
.br
It is not allowed to use standard output as pseudo drive if it was not
among the start arguments. Do not try to fool this ban via backdoor addresses
to stdout.
.br
If stdout is used as drive, then -use_readline is permanently disabled.
Use of backdoors will cause severe memory and/or tty corruption.
.PP
Be aware that especially the superuser can write into any accessible file or
device by using its path with the "stdio:" prefix. Addresses without prefix
"stdio:" will only work if they lead to a MMC drive.
.br
One may use option
.B -ban_stdio_write
to surely prevent this risk and to allow only MMC drives.
.SS
.B Rock Ridge, POSIX, X/Open:
.br
.B Rock Ridge
is the name of a set of additional informations which enhance
an ISO 9660 filesystem so that it can represent a POSIX compliant filesystem
with ownership, access permissions, symbolic links, and other attributes.
.PP
This is what xorriso uses for a decent representation of the disk files
within the ISO image. Rock Ridge information is produced with any xorriso
image and xorriso will load for manipulation only Rock Ridge enhanced images.
.PP
xorriso is not named "porriso" because POSIX only guarantees 14 characters
of filename length. It is the X/Open System Interface standard XSI which
demands a file name length of up to 255 characters and paths of up to 1024
characters. Rock Ridge fulfills this demand.
.SS
.B Command processing:
.br
Commands are either actions or settings. They consist of a command word,
followed by zero or more parameter words. If the list of parameter words
is of variable length (indicated by "[...]" or "[***]") then it has to be
terminated by either the word "--" or the end of argument list or an end of
an input line.
It is not an error if "--" appears after the parameters of a command
with a fixed list length.
.PP
.B Pattern expansion
is a property of some particular commands and not a general
feature. It gets controlled by commands -iso_rr_pattern and -disk_pattern.
Commands which eventually use pattern expansion all have variable argument
lists which are marked in this man page by "[***]" rather than "[...]".
.br
Some other commands perform pattern matching unconditionally.
.PP
Command and parameter words are either read from program arguments, where one
argument is one word, or from input lines where words are recognized similar
to the quotation rules of a shell parser.
.br
xorriso is not a shell, although it might appear so on first glimpse.
Be aware that the interaction of quotation marks and pattern symbols like "*"
differs from the usual shell parsers. In xorriso, a quotation mark does not
make a pattern symbol literal.
.PP
When the program begins then it first looks for argument -no_rc. If this is
not present then it looks for its startup files and
eventually reads their content as command input lines. Then it interprets
the program arguments as commands and parameters and finally it enters
dialog mode if command -dialog "on" was executed up to then.
.PP
The program ends either by command -end, or by the end of program arguments
if not dialog was enabled up to that moment, or by a problem
event which triggers the threshold of command -abort_on.
.SS
.B Dialog, Readline, Result pager:
.br
Dialog mode prompts for an input line, parses it into words, and performs
them as commands with their parameters. It provides assisting services
to make dialog more comfortable.
.PP
Readline is an enhancement for the input line. You may know it already from
the bash shell. Whether it is available in xorriso depends on the availability
of package readline-dev at the time when xorriso was built from its sourcecode.
.br
It allows to move the cursor over the text in the line by help of the
Leftward and the Rightward arrow key.
Text may be inserted at the cursor position. The Delete key removes the
character under the cursor. Upward and Downward arrow keys navigate through
the history of previous input lines. 
.br
See man readline for more info about libreadline.
.PP
Option -page activates a builtin result text pager which may be convenient in
dialog. After an action has put out the given number of terminal lines,
the pager prompts the user for a line of input.
.br
An empty line lets xorriso resume work until the next page is put out.
.br
The single character "@" disables paging for the current action.
.br
"@@@", "x", "q", "X", or "Q" urge the current action to abort and suppress
further result output.
.br
Any other line will be interpreted as new dialog line. The current action
is urged to abort. Afterwards, the input line is executed.
.PP
Some actions apply paging to their info output, too.
.br
The urge to abort may or may not be obeyed by the current action. All actions
try to abort as soon as possible.
.br
.SH OPTIONS
.br
All command words are shown with a leading dash although this dash is not
mandatory for the option to be recognized. There may be future emulation
modes, where dashes may become mandatory in order to distinguish options
from file addresses.
.br
Normally any number of leading dashes is ignored with command words and
inner dashes are interpreted as underscores.
.TP
.B Aquiring source and target drive:
.TP
\fB\-dev\fR address
Set input and output drive to the same address and load an eventual ISO image.
If there is no ISO image then create a blank one.
Set the image expansion method to growing.
.br
This is only allowed as long as no changes are pending in the currently
loaded ISO image. Eventually  one has to perform -commit or -rollback first.
Violation yields a FAILURE event.
.br
Special address string "-" means standard output, to which several restrictions
apply. See above paragraph "Libburn drives".
.br
An empty address string "" gives up the current device
without aquiring a new one.
.TP
\fB\-indev\fR address
Set input drive and load an eventual ISO image. If the new input drive differs
from -outdev then switch from growing to modifying. The same rules and
restrictions apply as with -dev.
.TP
\fB\-outdev\fR address
Set output drive and if it differs from the input drive then switch from
growing to modifying. Unlike -dev and -indev this action does not load a
new ISO image. So it can be performed even if there are pending changes.
.br
-outdev can be performed without previous -dev or -indev. In that case an
empty ISO image with no changes pending is created. It can either be populated
by help of -add or it can be discarded silently if -dev or -indev are
performed afterwards.
.br
Special address string "-" means standard output, to which several restrictions
apply. See above paragraph "Libburn drives".
.br
An empty address string "" gives up the current output drive
without aquiring a new one. No writing is possible without an output drive.
.TP
\fB\-load\fR entity id
Load a particular (possibly outdated) ISO image from a -dev or -indev which
hosts more than one session. Usually all available sessions are shown with
option -toc.
.br
entity depicts the kind of addressing. id depicts the particular
address. The following entities are defined:
.br
"auto" with any id addresses the last session in -toc. This is the default.
.br
"session" with id being a number as of a line "ISO session", column "Idx".
.br
"track" with id being a number as of a line "ISO track", column "Idx".
.br
"lba" or "sbsector" with a number as of a line "ISO ...", column "sbsector".
.br
"volid" with a text as of a line "ISO ...", column "Volume Id".
.br
Adressing a non-existing entity or one which does not represent an ISO
image will either abandon -indev or at least lead to a blank image.
.br
If an input drive is set at the moment when -load is executed, then the
addressed ISO image is loaded immediately. Else, the setting will be pending
until the next -dev or -indev. After the image has been loaded once, the
setting is valid for -rollback until next -dev or -indev, where it
will be reset to "auto".
.TP
\fB\-rom_toc_scan\fR "on"|"off"
Read-only drives do not tell the actual media type but show any media as
ROM (e.g. as DVD-ROM). The session history of MMC multi-session media might
be truncated to first and last session or even be completely false.
(The eventual emulated history of overwriteable media is not affected by this.)
.br
To have in case of failure a chance of getting the session history and
especially the address of the last session, there is a scan for ISO 9660
filesystem headers which might help but also might yield worse results
than the drive's table of content. At its end it can cause read attempts
to invalid addresses and thus ugly drive behavior.
.br
To be in effect, -rom_toc_scan has to be enabled by "on" before the -*dev
command which aquires drive and media.
.TP
\fB\-ban_stdio_write\fR
Allow for writing only the usage of MMC optical drives. Disallow
to write the result into files of nearly arbitrary type.
Once set, this command cannot be revoked.
.TP
.B Data manipulations:
.PP
The following commands expect file addresses of two kinds:
.br
.B disk_path
is a path to an object in the local filesystem tree.
.br
.B iso_rr_path
is the Rock Ridge name of a file object in the ISO image. (Do not
confuse with the lowlevel ISO 9660 names visible if Rock Ridge gets ignored.)
.PP
Note that in the ISO image you are as powerful as the superuser. Access
permissions of the existing files in the image do not apply to your write
operations. They are intended to be in effect with the read-only mounted image.
.PP
If the iso_rr_path of a newly inserted file leads to an existing
file object in the ISO image, then the following collision handling
happens:
.br
If both objects are directories then they get merged by recursively inserting
the subobjects from filesystem into ISO image.
If other file types collide then the setting of command
.B \-overwrite
decides.
.br
Renaming of files has similar collision handling, but directories can only
be replaced, not merged. Directories can hardly collide on renaming because
of the shell-like behavior of -mv: if a file object hits an existing directory
then it gets inserted rather than trying to replace that directory.
Nevertheless, the overwriting rules apply if an operation of xorriso
ever attempts to do such a replacement.
.PP
The commands in this section alter the ISO image and not the local filesystem.
.TP
\fB\-iso_rr_pattern\fR "on"|"ls"|"off"
Set the pattern expansion mode for the iso_rr_path arguments of several
commands which support this feature.
.br
.B Pattern expansion
converts a list of pattern words into a list of existing file addresses.
Eventual unmatched pattern words appear themselves in that result list, though.
.br
Pattern matching supports the usual shell parser wildcards '*' '?' '[xyz]'
and respects '/' as separator which may only be matched literally.
.br
Setting "off" disables this feature for all commands which are marked in this
man page by "iso_rr_path [***]" or "iso_rr_pattern [***]".
.br
Setting "on" enables it for all those commands.
.br
Setting "ls" enables it only for those which are marked by
"iso_rr_pattern [***]".
.br
Default is "on".
.TP
\fB\-disk_pattern\fR "on"|"ls"|"off"
Set the pattern expansion mode for the disk_path arguments of several
commands which support this feature.
.br
Setting "off" disables this feature for all commands which are marked in this
man page by "disk_path [***]" or "disk_pattern [***]".
.br
Setting "on" enables it for all those commands.
.br
Setting "ls" enables it only for those which are marked by
"disk_pattern [***]".
.br
Default is "ls".
.TP
\fB\-add\fR pathspec [...] | disk_path [***]
Insert the given files or directory trees from filesystem
into the ISO image.
.br
If -pathspecs is set to "on" then pattern expansion is always disabled and
character '=' has a special meaning. It eventually separates the ISO image path
from the disk path:
.br
iso_rr_path=disk_path
.br
The separator '=' can be escaped by '\\'.
If iso_rr_path does not begin with '/' then -cd is prepended.
If disk_path does not begin with '/' then -cdx is prepended.
.br
If no '=' is given then the word is used as both, iso_rr_path and disk path.
If in this case the word does not begin with '/' then -cdx is prepended to
the disk_path and -cd is prepended to the iso_rr_path.
.br
If -pathspecs is set to "off" then eventual -disk_pattern expansion applies.
The resulting words are used as both, iso_rr_path and disk path. Eventually
-cdx gets prepended to disk_path and -cd to iso_rr_path.
.TP
\fB\-add_plainly\fR mode
If set to mode "unknown" then any command word that does not begin with "-" and
is not recognized as known command will be subject to a virtual -add command.
I.e. it will be used as pathspec or as disk_path and added to the image.
Eventually -disk_pattern expansion applies to disk_paths.
.br
Mode "dashed" is similar to "unknown" but also adds unrecognized command
words even if they begin with "-".
.br
Mode "any" announces that all further words are to be added as pathspecs
or disk_paths. This does not work in dialog mode.
.br
Mode "none" is the default. It prevents any words from being understood
as files to add, if they are not parameters to appropriate commands.
.TP
\fB\-path_list\fR disk_path
Like -add but read the parameter words from file disk_path
or standard input if disk_path is "-". 
The list must contain exactly one pathspec resp. disk_path pattern per line. 
.TP
\fB\-map\fR disk_path iso_rr_path
Insert file object disk_path into the ISO image as iso_rr_path. If disk_path
is a directory then its whole sub tree is inserted into the ISO image.
.TP
\fB\-map_single\fR disk_path iso_rr_path
Like -map, but if disk_path is a directory then its sub tree is not inserted.
.TP
\fB\-update\fR disk_path iso_rr_path
Compare file object disk_path with file object iso_rr_path. If they do not
match, then perform the necessary image manipulations to make iso_rr_path
a matching copy of disk_path. This comparison will imply lengthy content
reading before a decision is made. On the other hand it strives for the
smallest possible amount of add-on data which is needed to achieve the
matching copy.
.br
If disk_path is a directory and iso_rr_path does not exist yet, then the
whole subtree will be inserted. Else only directory attributes will be
updated.
.TP
\fB\-update_r\fR disk_path iso_rr_path
Like -update but working recursively. I.e. all file objects below both
addresses get compared whether they have counterparts below the other address
and whether both counterparts match. If there is a mismatch then the necessary
update manipulation is done.
.br
Note that the comparison result may depend on option -follow. Its setting
should always be the same as with the first adding of disk_path as iso_rr_path.
.br
If iso_rr_path does not exist yet, then it gets added. If disk_path does not
exist, then iso_rr_path gets deleted.
.br
-update_r is also a convenient compromise between -add addressing and -cpr
addressing: Its semantics is similar to -add and thus avoids the pitfalls
inherited from cp -r behavior. Its syntax resembles cp, though.
.TP
\fB\-cut_out\fR disk_path byte_offset byte_count iso_rr_path
Map a byte interval of a regular disk file into a regular file in the ISO
image.
This may be necessary if the disk file is larger than a single media, or if
it exceeds the traditional limit of 2 GiB - 1 for old operating systems,
or the limit of 4 GiB - 1 for newer ones.
.br
A clumsy remedy for this limit is to backup file pieces and to concatenate
them at restore time. A well tested chopping size is 2047m.
It is permissible to request a higher byte_count than available. The
resulting file will be truncated to the correct size of a final piece.
To request a byte_offset higher than available yields no file in
the ISO image but a SORRY event.
E.g:
.br
 -cut_out /my/disk/file 0 2047m \\
.br
 /file/part_1_of_3_at_0_with_2047m_of_5753194821 \\
.br
 -cut_out /my/disk/file 2047m 2047m \\
.br
 /file/part_2_of_3_at_2047m_with_2047m_of_5753194821 \\
.br
 -cut_out /my/disk/file 4094m 2047m \\
.br
 /file/part_3_of_3_at_4094m_with_2047m_of_5753194821
.br
-cut_out is coordinated with -compare* and -update* if the names of the
part files follow a convention by which xorriso is able to recognize
file parts and process them accordingly:
.br
A disk file gets mapped to an ISO directory containing its split parts
as regular files. The parts have names which describe the splitting
by 5 numbers which are separated by some non-numerical text:
.br
part_number, total_parts, byte_offset, byte_count, disk_file_size
.br
Scaling characters like "m" or "k" are taken into respect and may
serve as separators as well. All digits are interpreted as decimal,
even if leading zeros are present.
.br
Not all parts have to be present on the same media. But those parts
which are present have to sit in the same directory. No other files
are allowed in there. Parts have to be disjoint. Their numbers have
to be plausible. E.g. byte_count must be valid as -cut_out argument
and it must be the same with all parts.
.br
If the disk file grows enough to need new parts then those get added
to the directory if it already contains all parts of the old disk file.
If not all parts are present, then only those present parts will
be updated.
.TP
\fB\-cpr\fR disk_path [***] iso_rr_path
Insert the given files or directory trees from filesystem 
into the ISO image.
.br
The rules for generating the ISO addresses are similar as with
shell command cp -r. Nevertheless, directories of the iso_rr_path
are created if necessary. Especially a not yet existing iso_rr_path
will be handled as directory if multiple disk_paths are present.
The leafnames of the multiple disk_paths will be grafted under that
directory as would be done with an existing directory.
.br
If a single disk_path is present then a non-existing iso_rr_path will
get the same type as the disk_path.
.br
If a disk_path does not begin with '/' then -cdx is prepended.
If the iso_rr_path does not begin with '/' then -cd is prepended. 
.TP
\fB\-rm\fR iso_rr_path [***]
Delete the given files from the ISO image.
.br
Note: This does not free any space on the -indev media, even if
the deletion is committed to that same media.
.br
The image size will shrink if the image is written to a different
media in modification mode.
.TP
\fB\-rm_r\fR iso_rr_path [***]
Delete the given files or directory trees from the ISO image.
See also the note with option -rm.
.TP
\fB\-mv\fR iso_rr_path [***] iso_rr_path
Rename the given file objects in the ISO tree to the last
argument in the list. Use the same rules as with shell command mv.
.br
If pattern expansion is enabled and if the last argument contains wildcard
characters then it must match exactly one existing file address, or else the
command fails with a FAILURE event.
.TP
\fB\-chown\fR uid iso_rr_path [***]
Set ownership of file objects in the ISO image. uid may either be a decimal
number or the name of a user known to the operating system.
.TP
\fB\-chown_r\fR uid iso_rr_path [***]
Like -chown but affecting all files below eventual directories.
.TP
\fB\-chgrp\fR gid iso_rr_path [***]
Set group attribute of file objects in the ISO image. gid  may either be a
decimal number or the name of a group known to the operating system.
.TP
\fB\-chgrp_r\fR gid iso_rr_path [***]
Like -chgrp but affecting all files below eventual directories.
.TP
\fB\-chmod\fR mode iso_rr_path [***]
Equivalent to shell command chmod in the ISO image.
mode is either an octal number beginning with "0" or a comma separated
list of statements of the form [ugoa]*[+-=][rwxst]* .
.br
Like: go-rwx,u+rwx .
.br
.B Personalities:
u=user, g=group, o=others, a=all
.br
.B Operators:
+ adds given permissions, - revokes given permissions,
= revokes all old permissions and then adds the given ones.
.br
.B Permissions:
r=read, w=write, x=execute|inspect, s=setuid|setgid, t=sticky bit
.br
For octal numbers see man 2 stat.
.TP
\fB\-chmod_r\fR mode iso_rr_path [***]
Like -chmod but affecting all files below eventual directories.
.TP
\fB\-alter_date\fR type timestring iso_rr_path [***]
Alter the date entries of a file in the ISO image. type is
one of "a", "m", "b" for access time, modification time,
both times.
.br
timestring may be in the following formats
(see also section EXAMPLES):
.br
As expected by program date:
 MMDDhhmm[[CC]YY][.ss]]
.br
As produced by program date:
 [Day] MMM DD hh:mm:ss [TZON] YYYY
.br
Relative times counted from current clock time:
 +|-Number["s"|"h"|"d"|"w"|"m"|"y"]
.br
where "s" means seconds, "h" hours, "d" days, "w" weeks, "m"=30d,
"y"=365.25d plus 1d added to multiplication result.
.br
Absolute seconds counted from Jan 1 1970:
 =Number
.br
xorriso's own timestamps:
 YYYY.MM.DD[.hh[mm[ss]]]
.br
scdbackup timestamps:
 YYMMDD[.hhmm[ss]]
.br
where "A0" is year 2000, "B0" is 2010, etc.
.TP
\fB\-alter_date_r\fR type timestring iso_rr_path [***]
Like -alter_date but affecting all files below eventual directories.
.TP
\fB\-find\fR iso_rr_path [-name pattern] [-type t] [-exec action [params]] --
A very restricted substitute for shell command find in the ISO image.
It performs an action on matching file objects at or below iso_rr_path.
.br
Optional -name pattern is not expanded but used for comparison with
the particular file names of the eventual directory tree underneath
iso_rr_path. If no -name pattern is given, then any file name matches.
.br
The optional -type test restricts matching to files of the given type:
"block", "char", "dir", "pipe", "file", "link", "socket",
"Xotic" which eventually matches what is not matched by the other types.
.br
Only the first letter is interpreted.  E.g.: -find / -type d
.br
If a file matches then the action is performed. Default action is "echo",
i.e. to print the address of the found file. Other actions are certain
xorriso commands which get performed on the found files. These commands
may have specific parameters. See also their particular descriptions.
.br
"chown" and "chown_r" change the ownership and get the user id as param. E.g.:
.br
  -find / -exec chown thomas --
.br
"chgrp" and "chgrp_r" change the group attribute and get the group id as param.
E.g.:
.br
  -find / name 'news*' -type d -exec chgrp_r staff --
.br
"chmod" and "chmod_r" change access permissions and get a mode string as param.
E.g.:
.br
  -find / -exec chmod a-w,a+r --
.br
"alter_date" and "alter_date_r" change the timestamps.
They get a type character and a timestring as params. 
E.g.:
.br
  -find / -exec alter_date "m" "Dec 30 19:34:12 2007" --
.br
"lsdl" prints file information like shell command ls -dl.
E.g.:
.br
  -find / -exec lsdl --
.br
"compare" performs command -compare with the found file address as iso_rr_path
and the corresponding file address below its argument disk_path_start. For this
the iso_rr_path of the -find command gets replaced by the disk_path_start.
E.g.:
.br
  -find / -exec compare /home/thomas --
.br
"update" performs command -update with the found file address as iso_rr_path.
The corresponding file address is determined like with above "compare".
.br
E.g.:
.br
  -find / -exec update /home/thomas --
.br
"rm" removes the found iso_rr_path from the image if it is not a directory with
files in it. I.e. this "rm" includes "rmdir".
.br
E.g.:
.br
  -find / -name *.doc -exec rm --
.br
"rm_r" removes the found iso_rr_path from the image, including whole directory
trees.
.br
E.g.:
.br 
  -find /uh/oh -name *private* -exec rm_r --
.br
"find" performs another run of -find on the matching file address. It accepts
the same params as -find, except iso_rr_path.
E.g.:
.br
  -find / -name '???' -type d -exec find -name '[abc]*' -exec chmod a-w,a+r --
.br
If not used as last command in the line then the argument list
needs to get terminated by "--".
.TP
\fB\-mkdir\fR iso_rr_path [...]
Create empty directories if they do not exist yet.
Existence as directory generates a WARNING event, existence as
other file causes a FAILURE event.
.TP
\fB\-rmdir\fR iso_rr_path [***]
Delete empty directories.
.TP
\fB\-\-\fR
.br
Mark end of particular action argument list.
.TP
\fB\-rollback\fR
Discard the manipulated ISO image and reload it from -indev.
.TP
\fB\-rollback_end\fR
Discard the manipulated ISO image. End program without loading a new image.
.TP
.B Writing the result:
(see also paragraph about settings below)
.TP
\fB\-commit\fR
Perform the write operation. Afterwards eventually make the
-outdev the new -dev and load the image from there.
Switch from eventual modifiying mode to growing mode.
(A subsequent -outdev will activate modification mode.)
-commit is performed automatically at end of program if there
are uncommitted manipulations pending.
So, to perform a final write operation with no new -dev
and no new loading of image, rather execute option -end.
To suppress a final write, execute -rollback -end.
To eject outdev after write without new loading of image, use -commit_eject.
.br

Writing can last quite a while. It is not unnormal with several
types of media that there is no progress visible for the first
few minutes or that the drive gnaws on the media for a few
minutes after all data have been transmitted.
xorriso and the drives are in a client-server relationship.
The drives have much freedom about what to do with the media.
Some combinations of drives and media simply do not work,
despite the promises by their vendors.
If writing fails - or even the drive gets stuck and you need
to reboot - then try other media or another drive. The reason
for such failure is hardly ever in the code of the various
burn programs but you may well try some of those listed below
under SEE ALSO.
.TP
\fB\-eject\fR "in"|"out"|"all"
Eject the media in -indev, resp. -outdev, resp. both drives.
Note: It is not possible yet to effectively eject disk files.
.TP
\fB\-commit_eject\fR "in"|"out"|"all"|"none"
Combined -commit and -eject. When writing has finished do not make
-outdev the new -dev, and load no ISO image. Rather eject
-indev and/or -outdev. Eventually give up any non-ejected drive.
.TP
\fB\-blank\fR mode
Make media ready for writing from scratch (if not -dummy is activated).
.br
This affects only the -outdev not the -indev.
If both drives are the same and if the ISO image was altered
then this command leads to a FAILURE event.
Defined modes are:
  as_needed, fast, all, deformat, deformat_quickest
.br
"as_needed" cares for used CD-RW, DVD-RW and for used overwriteable media
by applying -blank "fast". It applies -format "full" to  yet unformatted
DVD-RAM or BD-RE.
.br
"fast" and "all" make CD-RW and unformatted DVD-RW re-usable,
or invalidate overwriteable ISO images.
.br
"deformat" converts overwriteable DVD-RW into unformatted ones.
.br
"deformat_quickest" is a faster way to deformat or blank DVD-RW
but produces media which are only suitable for a single session.
xorriso will write onto them only if option -close is set to "on".
.br
The progress reports issued by some drives while blanking are
quite unrealistic. Do not conclude success or failure from the
reported percentages. Blanking was successful if no SORRY event or
worse occured.
.TP
\fB\-format\fR mode
Convert unformatted DVD-RW into overwriteable ones, "de-ice" DVD+RW, format
newly purchased BD-RE, re-format DVD-RAM or BD-RE.
.br
Defined modes are:
.br
  as_needed, full, fast, by_index_<num>, fast_by_index_<num> 
.br
"as_needed" formats yet unformatted DVD-RW, DVD-RAM, BD-RE. Other media
are left untouched.
.br
"full" (re-)formats DVD-RW, DVD+RW, DVD-RAM, BD-RE.
.br
"fast" does the same as "full" but tries to be quicker.
.br
"by_index_" selects a format out of the descriptor list issued by option
-list_formats. The index number from that list is to be appended to the
mode word. E.g: "by_index_3".
.br
"fast_by_index_" does the same as "by_index_" but tries to be quicker.
.br
The formatting action has no effect on media if -dummy is activated.
.br
Formatting is normally needed only once during the lifetime of a media,
if ever. But it is a reason for re-formatting if:
.br
 DVD-RW was deformatted by -blank,
.br
 DVD+RW has read failures (re-formatting might help or not),
.br
 DVD-RAM or BD-RE shall change their amount of defect reserve.
.br
The progress reports issued by some drives while formatting are
quite unrealistic. Do not conclude success or failure from the
reported percentages. Formatting was successful if no SORRY event
or worse occured. Be patient with apparently frozen progress.
.TP
\fB\-list_formats\fR
Put out a list of format descriptors as reported by the output drive for
the current media. The list gives the index number after "Format idx",
a MMC format code, the announced size in blocks (like "2236704s")
and the same size in MiB. 
.br
MMC format codes are manifold. Most important are:
"00h" general formatting, "01h" increases reserve space for DVD-RAM,
"26h" for DVD+RW, "30h" for BD-RE with reserve space,
"31h" for BD-RE without reserve space.
.br
Smaller format size with DVD-RAM or BD-RE means more reserve space.
.TP
.B Settings for data insertion:
.TP
\fB\-not_mgt\fR code[:code[...]]
Control the behavior of the exclusion lists.
.br
Exclusion processing happens before disk_paths get mapped to the ISO image
and before disk files get compared with image files.
The absolute disk path of the source is matched against the -not_paths list.
The leafname of the disk path is matched against the patterns in the -not_leaf
list. If a match is detected then the disk path will not be regarded as an
existing file and not be added to the ISO image.
.br
Several codes are defined.
The _on/_off settings persist until they are revoked by their_off/_on
counterparts.
.br
"erase" empties the lists which were accumulated by -not_paths and -not_leaf.
.br
"reset" is like "erase" but also re-installs default behavior.
.br
"off" disables exclusion processing temporarily without invalidating
the lists and settings.
.br
"on" re-enables exclusion processing.
.br
"param_off" applies exclusion processing only to paths below disk_path
parameter of commands. I.e. explicitely given disk_paths are exempted
from exclusion processing.
.br
"param_on" applies exclusion processing to command parameters as well as
to files below such parameters.
.br
"subtree_off" with "param_on" excludes parameter paths only if they
match a -not_paths item exactly.
.br
"subtree_on" additionally excludes parameter paths which lead to a file
address below any -not_paths item.
.br
"ignore_off" treats excluded disk files as if they were missing. I.e. they
get reported with -compare and deleted from the image with -update.
.br
"ignore_on" keeps excluded files out of -compare or -update activities.
.TP
\fB\-not_paths\fR disk_path [***]
Add the given paths to the list of excluded absolute disk paths. If a given
path is relative, then the current -cdx is prepended to form an absolute path.
Eventual pattern matching happens at definition time and not when exclusion
checks are made.
.br
(Do not forget to end the list of disk_paths by "--")
.TP
\fB\-not_leaf\fR pattern
Add a single shell parser style pattern to the list of exclusions for
disk leafnames. These patterns are evaluated when the exclusion checks are
made.
.TP
\fB\-follow\fR occasion[:occasion[...]]
Enable or disable resolution of symbolic links and mountpoints under
disk_paths. This applies to actions -add, -du*x, -ls*x, -findx,
and to -disk_pattern expansion.
.br
There are two kinds of follow decisison to be made:
.br
"link" is the hop from a symbolic link to its target file object.
If enabled then symbolic links are handled as their target file objects,
else symbolic links are handled as themselves. 
.br
"mount" is the hop from one filesystem to another subordinate filesystem.
If enabled then mountpoint directories are handled as any other directory,
else mountpoints are handled as empty directories if they are encountered in
directory tree traversals.
.br
Less general than above occasions:
.br
"pattern" is mount and link hopping, but only during -disk_pattern expansion.
.br
"param" is link hopping for parameter words (after eventual pattern expansion).
If enabled then -ls*x will show the link targets rather than the links
themselves. -du*x, -findx, and -add will process the link targets but not
follow links in an eventual directory tree below the targets (unless "link"
is enabled). 
.br
Occasions can be combined in a colon separated list. All occasions
mentioned in the list will then lead to a positive follow decision. 
.br
"off" prevents any positive follow decision. Use it if no other occasion
applies.
.br
Shortcuts:
.br
"default" is equivalent to "pattern:mount:limit=100".
.br
"on" always decides positive. Equivalent to "link:mount".
.br

Not an occasion but an optional setting is:
.br
"limit="<number> which sets the maximum number of link hops.
A link hop consists of a sequence of symbolic links and a final target
of different type. Nevertheless those hops can loop. Example:
.br
  \fB$\fR ln -s .. uploop
.br
Link hopping has a builtin loop detection which stops hopping at the first
repetition of a link target. Then the repeated link is handled as itself
and not as its target.
Regrettably one can construct link networks which
cause exponential workload before their loops get detected.
The number given with "limit=" can curb this workload at the risk of truncating
an intentional sequence of link hops.
.TP
\fB\-pathspecs\fR "on"|"off"
Control parameter interpretation with xorriso actions -add and -path_list.
.br
"on" enables pathspecs of the form
.B target=source
like with program mkisofs -graft-points.
It also disables -disk_pattern expansion for command -add.
.br
"off" disables pathspecs of the form target=source
and eventually enables -disk_pattern expansion.
.TP                
\fB\-overwrite\fR "on"|"nondir"|"off"
Allow or disallow to overwrite existing files in the
ISO image by files with the same user defined name.
.br
With setting "off", name collisions cause FAILURE events.
With setting "nondir", only directories are protected by such events, other
existing file types get treated with -rm before the new file gets added.
Setting "on" allows automatic -rm_r. I.e. a non-directory can replace an
existing directory and all its subordinates.
.br
If restoring of files is enabled, then the overwrite rule applies to the
target file objects on disk as well, but "on" is downgraded to "nondir".
.TP
\fB\-split_size\fR number["k"|"m"]
Set the threshold for automatic splitting of regular files. Such splitting
maps a large disk file onto a ISO directory with several part files in it.
This is necessary if the size of the disk file exceeds 4 GiB - 1.
Older operating systems can handle files only if they are smaller than 2 GiB.
See also option -cut_out for more information about file parts.
.br
Default is 0 which will exclude files >= 4 GiB by a FAILURE event.
A well tested -split_size is 2047m. Sizes of 4 GiB or more are not permissible.
.TP                
.B Settings for result writing:
.TP
Rock Ridge info will be generated by the program unconditionally.
.TP
\fB\-joliet\fR "on"|"off"
If enabled by "on", generate Joliet info additional to Rock Ridge info.
.TP
\fB\-volid\fR text
Specifies the volume ID. xorriso accepts any text up to 32 characters,
but according to rarely obeyed specs stricter rules apply:
.br
ECMA 119 demands character set [A-Z0-9_]. Like: "IMAGE_23"
.br
Joliet allows 16 UCS-2 characters. Like: "Windows name"
.br
Be aware that the volume id might get used automatically as name of the
mount point when the media is inserted into a playful computer system.
.br
If an ISO image gets loaded while the volume ID is set to default "ISOIMAGE"
or to "", then the volume ID of the loaded image will become the effective
volume id for the next write run. But as soon as command -volid is performed
afterwards, this pending id is overridden by the new setting.
.br 
Consider this when setting -volid "ISOIMAGE" before executing -dev, -indev,
or -rollback.
If you insist in -volid "ISOIMAGE", set it again after those commands.
.TP
\fB\-uid\fR uid
User id to be used for all files when the new ISO tree gets written to media.
.TP
\fB\-gid\fR gid
Group id to be used for all files when the new ISO tree gets written to media.
.TP
\fB\-speed\fR number[k|m|c|d]
Set the burn speed. Default is 0 = maximum speed.
Speed can be given in media dependent numbers or as a
desired throughput per second in MMC compliant kB (= 1000)
or MB (= 1000 kB). Media x-speed factor can be set explicity
by "c" for CD and "d" for DVD. Example speeds:
.br
 706k = 706kB/s = 4c = 4xCD
.br
 5540k = 5540kB/s = 4d = 4xDVD
.br
If there is no hint about the speed unit attached, then the
media in the -outdev will decide. Default unit is CD = 176.4k.
.br
MMC drives usually activate their own idea of speed and take
the speed value given by the burn program only as upper limit
for their own decision.
.TP
\fB\-stream_recording\fR "on"|"off"
Setting "on" tries to circumvent the management of defects on DVD-RAM and
DVD+RW. Defect management keeps partly damaged media usable. But it reduces
write speed to half nominal speed even if the media is in perfect shape.
For the case of flawless media, one may use -stream_recording "on" to get
full speed. 
.TP
\fB\-dummy\fR "on"|"off"
If "on" then simulate burning or refuse with FAILURE event if
no simulation is possible, do neither blank nor format.
.TP
\fB-fs\fR number["k"|"m"]
Set the size of the fifo buffer which smoothens the data
stream from ISO image generation to media burning. Default
is 4 MiB, minimum 64 kiB, maximum 1 GiB.
The number may be followed by letter "k" or "m"
which means unit is kiB (= 1024) or MiB (= 1024 kiB).
.TP
\fB\-close\fR "on"|"off"
If "on" then mark the written media as not appendable
any more (if possible at all with the given type of target media).
.br
This is the contrary of cdrecord, wodim, cdrskin option -multi,
and is one aspect of growisofs option -dvd-compat.
.TP
\fB\-padding\fR number["k"|"m"]
Append the given number of extra bytes to the image stream.
This is a traditional remedy for a traditional bug in block
device read drivers. Needed only for CD recordings in TAO mode.
Since one can hardly predict on what media an image might end up,
xorriso adds the traditional 300k of padding by default to all images.
.br
For images which will never get to a CD it is safe to use -padding 0 .
.TP
\fB\-boot_image\fR "any"|"isolinux" "discard"|"keep"|"patch"
Defines the handling of an eventual boot image (El-Torito) which has been read
from an existing ISO image. All types ("any") can be discarded or kept
unaltered. The latter makes only sense if the format of the boot image is
relocatable without content changes.
.br
The boot image type "isolinux" can be kept unaltered (not advisable), or
discarded, or it can be patched to match its relocation. In the latter case
the resulting ISO image is bootable if the boot image was really complying
to the isolinux standard.
.br
Creation of new boot images is not yet possible.
.br
CAUTION:
This is an expert option. xorriso is not an expert yet.
It cannot recognize the inner form of boot images.
So the user has already to know about the particular needs of the
bootimage which is present on the input media.
Most safe is the default: "any" "discard".
.TP
.B Exception processing:
.PP
Since the tasks of xorriso are manifold and prone to external influence, there
may arise the need for xorriso to report and handle problem events.
.br
Those events get classified when they are detected by one of the software
modules and forwarded to reporting and evaluation modules which decide about
reactions. Event classes are sorted by severity:
.br
"NEVER" The upper end of the severity spectrum.
.br
"ABORT" The program is being aborted and on its way to end.
.br
"FATAL" The main purpose of the run failed
or an important resource failed unexpectedly.
.br
"FAILURE" An important part of the job could not be performed.
.br
"MISHAP" A FAILURE which can be tolerated during ISO image generation.
.br
"SORRY" A less important part of the job could not be performed.
.br
"WARNING" A situation is suspicious of being not intended by the user.
.br
"HINT" A proposal to the user how to achieve better results.
.br
"NOTE" A harmless information about noteworthy circumstances.
.br
"UPDATE" A pacifier message during long running operations.
.br
"DEBUG" A message which would only interest the program developers.
.br
"ALL" The lower end of the severity spectrum.
.TP
\fB\-abort_on\fR severity
Set the severity threshold for events to abort the program.
.br
Useful: "NEVER", "ABORT", "FATAL", "FAILURE" , "MISHAP", "SORRY"
.br
It may become necessary to abort the program anyway, despite
the setting by this option. Expect not many "ABORT" events to
be ignorable.
.br
A special property of this option is that it works preemptive if given as
program start argument. I.e. the first -abort_on setting among the
start arguments is in effect already when the first operations of xorriso
begin. Only "-abort_on" with dash "-" is recognized that way.
.TP
\fB\-return_with\fR severity exit_value
Set the threshold and exit_value to be returned at program end if no abort
has happened. This is to allow xorriso to go on after problems but to get
a failure indicating exit value from the program, nevertheless.
Useful is a value lower than the -abort_on threshold, down to "WARNING".
.br
exit_value may be either 0 (indicating success to the starter of the program)
or a number between 32 and 63. Some other exit_values are used by xorriso if
it decides to abort the program run:
.br
1=abort due to external signal
.br
2=no program arguments given
.br
3=creation of xorriso main object failed
.br
4=failure to start libburnia-project.org libraries
.br
5=program abort during argument processing
.br
6=program abort during dialog processing
.TP
\fB\-report_about\fR severity
Set the threshold for events to be reported.
.br
Useful:  "SORRY", "WARNING", "HINT", "NOTE", "UPDATE", "DEBUG", "ALL"
.br
Regardless what is set by -report_about, messages get always reported if they
reach the severity threshold of -abort_on .
.br
Event messages are sent to the info channel "I" which is usually stderr
but may be influenced by command -pkt_output.
Info messages which belong to no event get attributed severity "NOTE".
.br
A special property of this option is that the first -report_about setting
among the start arguments is in effect already when the first operations
of xorriso begin. Only "-report_about" with dash "-" is recognized that way.
.TP
\fB\-error_behavior\fR occasion behavior
Control the program behavior at problem event occasions.
.br
For now this applies only to occasion "image_loading" which is given while
an image tree is read from the input device. There are three behaviors
available:
.br
"best_effort" goes on with reading after events with severity below FAILURE
if the threshold of option -abort_on allows this.
.br
"failure" aborts image tree reading on first event of at least SORRY.
It issues an own FAILURE event.
.br
"fatal" acts like "failure" but issues the own event as FATAL.
This is the default.
.TP
.B Dialog mode control:
.TP
\fB\-dialog\fR "on"|"off"
Enable or disable to enter dialog mode after all arguments
are processed. In dialog mode input lines get prompted via
readline or from stdin.
.TP
\fB\-page\fR length width
Describe terminal to the text pager. See also above, paragraph Result pager.
.br
If parameter length is nonzero then the user gets prompted after that
number of terminal lines. Zero length disables paging.
.br
Parameter width is the number of characters per terminal line. It is used
to compute the number of terminal lines which get occupied by an output line.
A usual terminal width is 80.
.TP
\fB\-use_readline\fR "on"|"off"
If "on" then use readline for dialog. Else use plain stdin.
.br
See also above, paragraph Dialog, Readline, Result pager.
.TP
\fB\-reassure\fR "on"|"tree"|"off"
If "on" then ask the user for "y" or "n":
.br
before deleting or overwriting any file in the ISO image,
.br
before overwriting any disk file during restore operations,
.br
before rolling back pending image changes,
.br
before committing image changes to media,
.br
before changing the input drive,
.br
before blanking or formatting media,
.br
before ending the program.
.br
With setting "tree" the reassuring prompt will appear for an eventual
directory only once and not for each file in its whole subtree.
.br
Setting "off" silently kills any kind of image file object resp. performs
above irrevocable actions.
.br
To really produce user prompts, option -dialog needs to be set to "on".
Note that the prompt does not appear in situations where file removal
is forbidden by option -overwrite. -reassure only imposes an additional
curb for removing existing file objects.
.br
Be aware that file objects get deleted from the ISO image immediately
after confirmation. They are gone even if the running command gets aborted 
and its desired effect gets revoked. In case of severe mess-up, consider to
use -rollback to revoke the whole session.
.TP
.B Drive and media related inquiry actions:
.TP
\fB\-toc\fR
.br
Show media specific table of content. This is the media session history,
not the ISO image directory tree.
.br
In case of overwriteable media holding a valid ISO image, a single session
gets fabricated from the ISO image size info. But if the first session on the
overwriteable media was written by xorriso then in most cases a complete
session history can be emulated.
.br
A drive which is incapable of writing may show any media as CD-ROM or DVD-ROM
with only one or two sessions on it. The last of these sessions is supposed
to be the most recent real session then.
.br
Some read-only drives and media show no usable session history at all.
Eventually option -rom_toc_scan might help.
.TP
\fB\-devices\fR
Show list of available MMC drives with the addresses of
their libburn standard device files.
.br
This is only possible when no ISO image changes are pending.
After this option was executed, there is no drive current
and no image loaded. Eventually one has to aquire a drive again.
.br
In order to be visible, a device has to offer rw-permissions
with its libburn standard device file. Thus it might be only the
.B superuser
who is able to see all drives.
.br
Drives which are occupied by other processes get not shown.
.TP
\fB\-print_size\fR
Print the foreseeable consumption of 2048 byte blocks
by next -commit. This can last a while as a -commit gets
prepared and only in last moment is revoked by this option.
.TP
\fB\-tell_media_space\fR
Print available space on output media and the free space after
subtracting already foreseeable consumption by next -commit.
.TP
.B Navigation in ISO image and disk filesystem:
.TP
\fB\-cd\fR iso_rr_path
Change the current working directory in the emerging ISO
image as it is at the moment. This is prepended to iso_rr_paths
which do not begin with '/'.
.br
It is possible to set the working directory to a path which does not exist
yet in the ISO image. The necessary parent directories will be created when
the first file object is inserted into that virtual directory.
Use -mkdir if you want to enforce the existence of the directory already at
first insertion.
.TP
\fB\-cdx\fR disk_path
Change the current working directory on filesystem.
To be prepended to disk_paths which do not begin with '/'.
.TP
\fB\-pwd\fR
.br
Tell the current working directory in the ISO image.
.TP
\fB\-pwdx\fR
.br
Tell the current working directory on local filesystem.
.TP
\fB\-ls\fR iso_rr_pattern [***]
List files in the ISO image which match shell patterns
(i.e. with wildcards '*' '?' '[a-z]').
If a pattern does not begin with '/' then it is compared with addresses
relative to -cd, the current working directory in the ISO image.
.br
Directories are listed by their content rather than as single file item.
.br
Pattern expansion may be disabled by command -iso_rr_pattern.
.TP
\fB\-lsd\fR iso_rr_pattern [***]
Like -ls but listing directories as themselves and not by their content.
This resembles shell command ls -d.
.TP
\fB\-lsl\fR iso_rr_pattern [***]
Like -ls but also list some of the file attributes. 
Output format resembles shell command ls -ln.
.TP
\fB\-lsdl\fR iso_rr_pattern [***]
Like -lsd but also list some of the file attributes. 
Output format resembles shell command ls -dln.
.TP
\fB\-lsx\fR disk_pattern [***]
List files on local filesystem which match shell patterns. Patterns which do
not begin with '/' are used relative to -cdx, the current working directory in
the local filesystem.
.br
Directories are listed by their content rather than as single file item.
.br
Pattern expansion may be disabled by command -disk_pattern.
.TP
\fB\-lsdx\fR disk_pattern [***]
Like -lsx but listing directories as themselves and not by their content.
This resembles shell command ls -d.
.TP
\fB\-lslx\fR disk_pattern [***]
Like -lsx but also listing some of the file attributes.
Output format resembles shell command ls -ln.
.TP
\fB\-lsdlx\fR disk_pattern [***]
Like -lsdx but also listing some of the file attributes.
Output format resembles shell command ls -dln.
.TP
\fB\-du\fR iso_rr_pattern [***]
Recursively list size of directories and files in the ISO image
which match one of the patterns.
similar to shell command du -k.
.TP
\fB\-dus\fR iso_rr_pattern [***]
List size of directories and files in the ISO image 
which match one of the patterns.
Similar to shell command du -sk.
.TP
\fB\-dux\fR disk_pattern [***]
Recursively list size of directories and files in the local filesystem
which match one of the patterns, similar to shell command du -k.
.TP
\fB\-dusx\fR disk_pattern [***]
List size of directories and files in the local filesystem
which match one of the patterns.
Similar to shell command du -sk.
.TP
\fB\-findx\fR disk_path [-name pattern] [-type t] [-exec action [params]] --
Like -find but operating on local filesystem and not on the ISO image.
This is subject to the settings of -follow.
.br
Find accepts the same -type arguments as -find. Additionally it recognizes
type "mountpoint" (or "m"). It matches subdirectories which reside on a
different device than their parent. It never matches the disk_path
given as start address for -findx.
.br
-findx accepts the -exec actions as does -find. But except the following few
actions it will allways perform action "echo".
.br
"in_iso" iso_rr_path_start reports the path if its counterpart exist in
the ISO image. For this the disk_path of the -find command gets replaced
by iso_rr_path_start.  E.g.:
.br
  -findx /home -exec in_iso /
.br
"not_in_iso" iso_rr_path_start reports the path if its counterpart does
not exist in the ISO image. The report format is the same as with command
-compare.
E.g.
.br
  -findx /home/thomas -exec not_in_iso /thomas_on_cd
.br
"add_missing" iso_rr_path_start adds the counterpart if it does not yet
exist in the ISO image. 
E.g.
.br
  -findx /home/thomas -exec add_missing /thomas_on_cd
.br
"is_full_in_iso" iso_rr_path_start reports if the counterpart in the ISO image
contains files. To be used with -type "m" to report mount points.
.br
"empty_iso_dir" iso_rr_path_start deletes all files from the counterpart
in the ISO image. To be used with -type "m" to truncate mount points.
.TP
\fB\-compare\fR disk_path iso_rr_path
Compare attributes and eventual data file content of a fileobject in the
local filesystem with a file object in the ISO image. The iso_rr_path may
well point to an image file object which is not yet committed, i.e. of which
the data content still resides in the local filesystem. Such data content is
prone to externally caused changes.
.br
If iso_rr_path is empty then disk_path is used as path in the ISO image too.
.br
Differing attributes are reported in detail, differing content is summarized.
Both to the result channel. In case of no differences no result lines are
emitted.
.TP
\fB\-compare_r\fR disk_path iso_rr_path
Like -compare but working recursively. I.e. all file objects below both
addresses get compared whether they have counterparts below the other address
and whether both counterparts match.
.TP
.B osirrox restore options:
.PP
Normally xorriso only writes to disk files which were given as stdio:
pseudo-drives or as log files.
But its alter ego, osirrox, is able to extract file objects
from ISO images and to create, overwrite, or delete file objects on disk.
.br
Disk file exclusions by -not_mgt, -not_leaf, -not_paths apply.
If disk file objects already exist then the settings of -overwrite and
-reassure apply. But -overwrite "on" only triggers the behavior
of -overwrite "nondir". I.e. directories cannot be deleted.
.br
Access permissions of files in the ISO image do not restrict restoring.
The permissions on disk have to allow writing, of course.
.TP
\fB\-osirrox\fR "on"|"device_files"|"off"[:option:...]
Setting "off" disables disk filesystem manipulations. This is the default
unless the program was started with leafname "osirrox". Elsewise
the capability to restore files can be enabled explicitly by -osirrox "on".
.br
To enable restoring of special files by "device_files" is potentially
dangerous.
The meaning of the number st_rdev (see man 2 stat) depends much on the
operating system. Best is to restore device files only to the same system
from where they were copied. If not enabled, device files in the ISO image
are ignored during restore operations.
.br
Due to a bug of previous versions, device files from previous sessions might
have been altered to major=0, minor=1. So this combination does not get
restored.
.br
Option "concat_split_on" is default. It enables restoring of split file
directories as data files if the directory contains a complete collection
of -cut_out part files.
.br
With option "concat_split_off" such directories are
handled like any other ISO image directory.
.TP
\fB\-extract\fR iso_rr_path disk_path
Restore the file objects at and underneath iso_rr_path to their corresponding
addresses at and underneath disk_path.
This is the inverse of -map or -update_r.
.br
If iso_rr_path is a directory and disk_path is an existing directory then
both trees will be merged. Directory attributes get extracted only if the disk
directory is newly created by the restore operation.
Disk files get removed only if they are to be replaced
by file objects from the ISO image.
.br
As many attributes as possible are copied together with restored
file objects.
.TP
\fB\-extract_single\fR iso_rr_path disk_path
Like -extract, but if iso_rr_path is a directory then its sub tree gets not
restored.
.TP
\fB\-cpx\fR iso_rr_path [***] disk_path
Extract single leaf file objects from the ISO image and store them under
the address given by disk_path. If more then one iso_rr_path is given then
disk_path must be a directory or non-existent. In the latter case it gets
created and the extracted files get installed in it with the same leafnames.
.br
Missing directory components in disk_path will get created, if possible.
.br
Directories are allowed as iso_rr_path only with -osirrox "concat_split_on"
and only if they actually represent a complete collection of -cut_out split
file parts.
.TP
\fB\-cpax\fR iso_rr_path [***] disk_path
Like -cpx but restoring mtime, atime as in ISO image and trying to set
ownership and group as in ISO image.
.TP
\fB\-cp_rx\fR iso_rr_path [***] disk_path
Like -cpx but also extracting whole directory trees from the ISO image.
.br
The resulting disk paths are determined as with shell command cp -r :
If disk_path is an existing directory then the trees will be inserted or merged
underneath this directory and will keep their leaf names. The ISO directory "/"
has no leaf name and thus gets mapped directly to disk_path.
.TP
\fB\-cp_rax\fR iso_rr_path [***] disk_path
Like -cp_rx but restoring mtime, atime as in ISO image and trying to set
ownership and group as in ISO image.
.TP
\fB\-paste_in\fR iso_rr_path disk_path byte_offset byte_count
Read the content of a ISO data file and write it into a data file on disk
beginning at the byte_offset. Write at most byte_count bytes.
This is the inverse of option -cut_out.
.TP
.B Command compatibility emulations:
.PP
Writing of ISO 9660 on CD is traditionally done by program mkisofs
as ISO 9660 image producer and cdrecord as burn program.
xorriso does not strive for their comprehensive emulation.
Nevertheless it is ready to perform some of its core tasks under control
of commands which in said programs trigger comparable actions.
The scope is for now only a single first data track to be written to blank or
overwriteable media. If possible the media will get closed afterwards.
Multi-session is yet only possible via xorriso's own commands.
.TP
\fB\-as\fR personality option [options] --
.br
Performs its variable length option list as sparse emulation of the program
depicted by the personality word. This is only allowed if no image changes
are pending. The input drive is given up.
.br

Personality "\fBmkisofs\fR" accepts the options listed with:
.br
  -as mkisofs -help --
.br
Among them: -R (always on), -J, -graft-points, -o, -path-list, -m, -print-size,
-V, -v, -version, pathspecs as with xorriso -add. A lot of options are not
supported and lead to failure of the mkisofs emulation. Some are ignored,
but better do not rely on this tolerance.
.br
-graft-points is equivalent to -pathspecs on. Note that pathspecs without "="
are interpreted differently than with xorriso option -add. Directories get
merged with the root directory of the ISO image, other filetypes get mapped
into that root directory.
.br
Other than with the "cdrecord" personality there is no automatic -commit at
the end of a "mkisofs" option list. Verbosity settings -v (= "UPDATE") and
-quiet (= "SORRY") persist. The output file, eventually chosen with -o,
persists until things happen like -commit, -rollback, -dev, or end of xorriso.
.br
If no output file was chosen before or during a "mkisofs" option list, then
standard output (-outdev "-") will get into effect before pathspecs get
added. If -o points to a regular file, then it will be truncated to 0 bytes
when finally writing begins. This truncation does not happen if the drive
is chosen by xorriso options before or after -as mkisofs.
Directories and symbolic links are no valid -o targets.
.br
Writing to stdout is possible only if -as "mkisofs" was among the start
arguments or if other start arguments pointed the output drive to
standard output.
.br
Personalites "\fBgenisoimage\fR" and "\fBgenisofs\fR"
are aliases for "mkisofs".
.br

Personality "\fBcdrecord\fR" accepts the options listed with:
.br
  -as cdrecord -help --
.br
Among them: -v, dev=, speed=, blank=, fs=, -eject, -atip, padsize=,
track source file path or "-" for standard input as track source.
.br
It ignores most other options of cdrecord and cdrskin but refuses on
-audio, -scanbus, -multi, -msinfo, --grow_overwriteable_iso,
and on blanking modes unknown to xorriso.
.br
dev= must be given as xorriso device address. Adresses like 0,0,0 or ATA:1,1,0
are not supported.
.br
If a track source is given, then an automatic -commit happens at the end of
the "cdrecord" option list.
.br
A much more elaborate libburn based cdrecord emulator is the program cdrskin.
.br
Personalites "\fBwodim\fR" and "\fBcdrskin\fR" are aliases for "cdrecord".
.TP
.B Scripting, dialog and program control features:
.TP
\fB\-no_rc\fR
.br
Only if used as first command line argument this option
prevents reading and interpretation of eventual startup
files. See section FILES below.
.TP
\fB\-options_from_file\fR fileaddress
Reads lines from fileaddress and executes them as dialog lines.
.TP
\fB\-help\fR
.br
Print helptext.
.TP
\fB\-version\fR
Print program name and version.
.TP
\fB\-history\fR textline
Copy textline into libreadline history.
.TP
\fB\-status\fR [mode|filter]
Print the current settings of xorriso.
Modes:
.br
  short... print only important or altered settings
.br
  long ... print all settings including defaults
.br
  long_history  like long plus history lines
.br
Filters begin with '-' and are compared literally against the
output lines of -status:long_history. A line is put out only
if its start matches the filter text. No wildcards.
.TP
\fB\-status_history_max\fR number
Set maximum number of history lines to be reported with -status "long_history".
.TP
\fB\-temp_mem_limit\fR number["k"|"m"]
Set the maximum size of temporary memory to be used for image dependent
buffering. Currently this applies to pattern expansion only.
.br
Default is 16m = 16 MiB, minimum 64k = 64 kiB, maximum 1024m = 1 GiB.
.TP
\fB\-print\fR  text
Print a text to result channel.
.TP
\fB\-prompt\fR text
Show text at beginning of output line and
wait for the user to hit the Enter key
resp. to send a line via stdin.
.TP
\fB\-errfile_log\fR mode path|channel
.br
If problem events are related to input files from the filesystem, then their
disk_paths can be logged to a file or to output channels R or I.
.br
Mode can either be "plain" or "marked". The latter causes marker lines which
give the time of log start, burn session start, burn session end, log end
or program end. In mode "plain", only the file paths are logged.
.br
If path is "-" or "-R" then the log is directed to the result channel.
Path "-I" directs it to the info message channel. Any text that does not
begin with "-" is used as path for a file to append the log lines.
.br
Problematic files can be recorded multiple times during one program run.
If the program run aborts then the list might not be complete because
some input file arguments might not have been processed at all.
.br
The errfile paths are transported as messages of very low priority "ERRFILE".
This transport becomes visible with -report_about "ALL".
.TP
\fB\-session_log\fR path
If path is not empty it gives the address of a plain text file where
a log record gets appended after each session. This log can be used to
determine the start_lba of a session for mount option sbsector= from
date or volume id.
.br
Record format is: timestamp start_lba size volume-id
.br
The first three items are single words, the rest of the line is the volume id.
.TP
\fB\-end\fR
.br
End program immediately
.TP
\fB#\fR any text
In dialog or file execution mode only and only as first
non-whitespace in line:
Do not execute the line but eventually store it in history.
.TP
.B Support for frontend programs talking into stdin and listening at stdout:
.TP
\fB\-pkt_output\fR "on"|"off"
Consolidate text output on stdout and classify each
line by a channel indicator:
.br
 'R:' for result lines,
.br
 'I:' for notes and error messages,
.br
 'M:' for -mark texts.
.br
Next is a decimal number of which only bit 0 has a meaning for now.
0 means no newline at end of payload, 1 means that the newline character at
the end of the output line belongs to the payload. After another colon follows
the payload text.
.br
Example:
.br
 I:1: enter option and arguments :
.TP
\fB\-logfile\fR channel fileaddress
Copy output of a channel to the given file.
.TP
\fB\-mark\fR text
If text is not empty it will get put out each time an
action has been completed.
.TP
\fB\-prog\fR text
Use text as this program's name in subsequent messages
.TP
\fB\-prog_help\fR text
Use text as this program's name and perform -help.
.br
.SH EXAMPLES
.SS
.B Overview of examples:
As superuser learn about available drives
.br
Blank media and compose a new ISO image as batch run
.br
A dialog session doing about the same
.br
Manipulating an existing ISO image on the same media
.br
Copy modified ISO image from one media to another
.br
Write a ISO image into a pipe (single-session only)
.br
Perform a single session run as of cdrtools traditions
.br
Adjust thresholds for verbosity, exit value and program abort
.br
Examples of input timestrings
.br
Incremental backup of a few directory trees
.SS
.B As superuser learn about available drives
Consider to give rw permissions to those users or groups
which shall be able to use the drives with xorriso.
.br
\fB$\fR xorriso -devices
.br
0  -dev '/dev/sr0' rwrw-- :  '_NEC    ' 'DVD_RW ND-4570A'
.br
1  -dev '/dev/sr1' rwrw-- :  'HL-DT-ST' 'DVDRAM GSA-4082B' 
.br
2  -dev '/dev/sr2' rwrw-- :  'PHILIPS ' 'SPD3300L' 
.SS
.B Blank media and compose a new ISO image as batch run
Aquire drive /dev/sr2, blank media resp. invalidate existing ISO image.
Add the files from hard disk directories /home/me/sounds and /pictures.
Omit some unwanted stuff by removing it from the image directory tree.
Re-add some wanted stuff.
.br
Because no -dialog "on" is given, the program will then end by committing the
session to media.
.br
\fB$\fR cd /home/me
.br
\fB$\fR xorriso -outdev /dev/sr2 \\
.br
 -blank as_needed \\
.br
 -map /home/me/sounds /sounds \\
.br
 -map /home/me/pictures /pictures \\
.br
 -rm_r \\
.br
   /sounds/indecent \\
.br
   '/pictures/*private*' \\
.br
   /pictures/confidential \\
.br
   -- \\
.br
 -cd / \\
.br
 -add pictures/confidential/work*
.br
Note that '/pictures/*private*' is a pattern for iso_rr_paths
while pictures/confidential/work* gets expanded by the shell
with addresses from the hard disk.
.SS
.B A dialog session doing about the same
.br
-pathspecs is already given as start argument. The other activities
are done as dialog input. The pager gets set to 20 lines of 80 characters.
.br
The drive is aquired by option -dev rather than -outdev in order to see
the message about its current content. By option -blank this content is
made ready for being overwritten and the loaded ISO image is made empty.
.br
In order to be able to eject the media, the session needs to be committed
explicitely.
.br
.B $ xorriso -dialog on -page 20 80 -disk_pattern on
.br
enter option and arguments :
.br
.B \-dev /dev/sr2
.br
enter option and arguments :
.br
.B \-blank as_needed
.br
enter option and arguments :
.br
.B \-map /home/me/sounds /sounds -map /home/me/pictures /pictures
.br
enter option and arguments :
.br
.B \-rm_r /sounds/indecent /pictures/*private* /pictures/confidential
.br
enter option and arguments :
.br
.B \-cdx /home/me/pictures -cd /pictures
.br
enter option and arguments :
.br
.B \-add confidential/office confidential/factory
.br
enter option and arguments :
.br
.B \-du /
.br
enter option and arguments :
.br
.B \-commit -eject all -end
.br
.SS
.B Manipulating an existing ISO image on the same media
Load image from drive.
Remove (i.e. hide) directory /sounds and its subordinates.
Rename directory /pictures/confidential to /pictures/restricted.
Change access permissions of directory /pictures/restricted.
Add new directory trees /sounds and /movies. Burn to the same media and eject.
.br
\fB$\fR xorriso -dev /dev/sr2 \\
.br
 -rm_r /sounds -- \\
.br
 -mv \\
.br
   /pictures/confidential \\
.br
   /pictures/restricted \\
.br
   -- \\
.br
 -chmod go-rwx /pictures/restricted -- \\
.br
 -map /home/me/prepared_for_dvd/sounds_dummy /sounds \\
.br
 -map /home/me/prepared_for_dvd/movies /movies \\
.br
 -commit -eject all
.SS
.B Copy modified ISO image from one media to another
Load image from input drive. Do the same manipulations as in the previous
example. Aquire output drive and blank it. Burn the modified image as
first and only session to the output drive.
.br
\fB$\fR xorriso -indev /dev/sr2 \\
.br
 -rm_r /sounds -- \\
.br
 ...
.br
 -outdev /dev/sr0 -blank as_needed \\
.br
 -commit -eject all
.SS
.B Write a ISO image into a pipe (single-session only)
\fB$\fR xorriso -outdev - \\
.br
 ...
.br
 | gzip >image.iso.gz
.SS
.B Perform a single session run as of cdrtools traditions
This shall illustrate how xorriso can act in either role.
Between both processes there can be performed arbitrary transportation
or filtering.
.br
\fB$\fR xorriso -as mkisofs -J -R /home/prepared_for_iso/tree | \\
.br
 xorriso -as cdrecord -v dev=/dev/sr0 blank=fast -eject - 
.SS
.B Adjust thresholds for verbosity, exit value and program abort
Be quite verbous, exit 32 if severity "FAILURE" was encountered,
do not abort prematurely but forcibly go on until the end of commands.
.br
\fB$\fR xorriso ... \\
.br
 -report_about UPDATE \\
.br
 -return_with FAILURE 32 \\
.br
 -abort_on NEVER \\
.br
 ...
.SS
.B Examples of input timestrings
.br
As printed by program date:
.B 'Thu Nov  8 14:51:13 CET 2007'
.br
The same without ignored parts:
.B 'Nov 8 14:51:13 2007'
.br
The same as expected by date:
.B 110814512007.13
.br
Four weeks in the future:
.B +4w
.br
The current time:
.B +0
.br
Three hours ago:
.B \-3h
.br
Seconds since Jan 1 1970:
.B =1194531416
.SS
.B Incremental backup of a few directory trees
This does the following to directories /open_source_project and /personal_mail
in the ISO image:
create them if not existing yet,
compare them with their disk counterparts,
add disk file objects which are missing yet,
overwrite those which are different on disk,
and delete those which have vanished on disk.
But do not add or overwrite files matching *.o, *.swp.
.br
\fB$\fR xorriso -dev /dev/sr0 \\
.br
 -volid PROJECTS_MAIL_"$(date '+%Y_%m_%d_%H%M%S')" \\
.br
 -not_leaf '*.o' -not_leaf '*.swp' \\
.br
 -update_r /home/thomas/open_source_projects /open_source_projects \\
.br
 -update_r /home/thomas/personal_mail /personal_mail \\
.br
 -commit -toc -eject all
.br
To be used several times on the same media, whenever an update of
the two disk trees to the media is desired. Begin with blank media and start
a new blank media when the run fails due to lack of remaining space on
the old one.
.br
This makes most sense with backups on non-erasable media like CD-R,
DVD-R, DVD+R if the full backup leaves substantial remaining capacity
on media and if the expected changes are much smaller than the full backup.
An update run will probably save no time but last longer than a full backup.
Another good reason may be given if read speed is much higher than write speed.
.br 
.br
With \fBmount\fR option \fB"sbsector="\fR it is possible to access the session
trees which represent the older backup versions. With CD media, Linux mount
accepts session numbers directly by its option "session=".
.br
Multi-session media and most overwriteable media written by xorriso can tell
the sbsector of a session by xorriso option -toc.
Another way to keep track of incremental sessions is to
set before writing a suitable path for xorriso option -session_log where
the sbsector number gets recorded as the second word in each line.
.br
Independently of mount there is xorriso option \fB-osirrox on\fR which enables
the builtin restore commands -extract, -cpx and others. They operate on the
session eventually selected by option \fB-load\fR.
.br
\fBDo not write more than about 50 sessions\fR to one multi-session media.
Theoretical limits are higher but in practice the media deteriorate more early.
It might also be that your operating system has a session limit with mount.
An overview of sessions is given by option -toc.
.br
Sessions on multi-session media are separated by several MB of unused blocks.
So with small sessions the payload capacity can become substantially lower
than the overall media capacity. If the remaining space on media does not
suffice for the next gap, the drive is supposed to close the media
automatically.
.br
\fBBetter do not use your youngest backup for -update_r\fR.
Have at least two media which you use alternatingly. So only older backups
get endangered by the new write operation, while the newest backup is
stored safely on a different media.
Always have a blank media ready to perform a full backup in case the update
attempt fails due to insufficient remaining capacity.
.br 
If you have enough re-useable media for a round-robin scheme then better do
full backups with blank media each time. Blanking can be achieved by
either a separate run:
.br
\fB$\fR xorriso -outdev /dev/sr0 -blank as_needed -eject all
.br
or in the update run by using option -blank "as_needed" before
option -update_r.
.br
.SH FILES
.SS 
.B Startup files:
.br
If not -no_rc is given as the first argument then xorriso attempts on startup
to read and execute lines from the following files:
.br
   /etc/default/xorriso
.br
   /etc/opt/xorriso/rc
.br
   /etc/xorriso/xorriso.conf
.br
   $HOME/.xorrisorc
.br
The files are read in the sequence given above, but none of them is required
for xorriso to function properly.
.br
.SH SEE ALSO
.TP
For mounting xorriso generated ISO 9660 images
.br
.BR mount(8)
.TP
Libreadline, a comfortable input line facility
.BR readline(3)
.TP
Other programs which produce ISO 9660 images
.br
.BR mkisofs(8),
.BR genisoimage(8)
.TP
Other programs which burn sessions to optical media
.BR growisofs(1),
.BR cdrecord(1),
.BR wodim(1),
.BR cdrskin(1) 
.br
.SH AUTHOR
Thomas Schmitt <scdbackup@gmx.net>
.br
for libburnia-project.org
.SH CREDITS
xorriso is in part based on work by Vreixo Formoso who provides libisofs
together with Mario Danic who also leads the libburnia team.
Thanks to Andy Polyakov who invented emulated growing,
to Derek Foreman and Ben Jansens who once founded libburn.
.br
Compliments towards Joerg Schilling whose cdrtools served me for ten years.