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Manual Reference Pages  -  ISOINFO (8)


devdump, isoinfo, isovfy, isodump - Utility programs for dumping and verifying iso9660 images.


Future Improvements
See Also


devdump isoimage

isodump isoimage

isoinfo [ options ] [ [ find expression ]]

isovfy isoimage


devdump is a crude utility to interactively display the contents of device or filesystem images. The initial screen is a display of the first 256 bytes of the first 2048 byte sector. The commands are the same as with isodump.

isodump is a crude utility to interactively display the contents of iso9660 images in order to verify directory integrity. The initial screen is a display of the first part of the root directory, and the prompt shows you the extent number and offset in the extent.

You can use the ’a’ and ’b’ commands to move backwards and forwards within the image. The ’g’ command allows you to goto an arbitrary extent, and the ’f’ command specifies a search string to be used. The ’+’ command searches forward for the next instance of the search string, and the ’q’ command exits devdump or isodump.

isoinfo is a utility to perform directory like listings of iso9660 images.

isovfy is a utility to verify the integrity of an iso9660 image. Most of the tests in isovfy were added after bugs were discovered in early versions of mkisofs. It isn’t all that clear how useful this is anymore, but it doesn’t hurt to have this around.


The options common to all programs are -help,-h,-version, i=name,dev=name. The isoinfo program has additional command line options. The options are:
print a summary of all options.
-d Print information from the primary volume descriptor (PVD) of the iso9660 image. This includes information about Rock Ridge, Joliet extensions and Eltorito boot information if present.
-f generate output as if a ’find . -print’ command had been run on the iso9660 image. You should not use the -l image with the -f option. The same output is created by calling isoinfo with -find -print
  This option acts a separator. If it is used, all isoinfo options must be to the left of the -find option. To the right of the -find option, mkisofs accepts the find command line syntax only. If the find expression includes a -print or -ls promary, the -l to isoinfo is ignored. If the find expression evaluates as true, the selected action (e.g. list the ISO-9660 directory) is performed.
-i iso_image
  Specifies the path of the iso9660 image that we wish to examine. The options -i and dev=target are mutual exclusive.
  Ignore errors. The commands by default aborts on several errors, such as read errors. With this option in effect, the commands try to continue. Use with care.
  Sets the SCSI target for the drive, see notes above. A typical device specification is dev=6,0 . If a filename must be provided together with the numerical target specification, the filename is implementation specific. The correct filename in this case can be found in the system specific manuals of the target operating system. On a FreeBSD system without CAM support, you need to use the control device (e.g. /dev/rcd0.ctl). A correct device specification in this case may be dev=/dev/rcd0.ctl:@ .

On Linux, drives connected to a parallel port adapter are mapped to a virtual SCSI bus. Different adapters are mapped to different targets on this virtual SCSI bus.

If no dev option is present, the program will try to get the device from the CDR_DEVICE environment.

If the argument to the dev= option does not contain the characters ’,’, ’/’, ’@’ or ’:’, it is interpreted as an label name that may be found in the file /etc/default/cdrecord (see FILES section).

The options -i and dev=target are mutual exclusive.

-debug Print additional debug information. This enables e.g. printing of all directory entries if a file has more than one directory entry and printing of more information from the primary volume descriptor.

In debug mode, Rock Ridge information is parsed with -R even if it is not standard compliant.

-l generate output as if a ’ls -lR’ command had been run on the iso9660 image. You should not use the -f image with the -l option.

The numbers in square brackets are the starting sector number as decimal number (based on 2048 bytes per sector) and the iso9660 directory flags as hexadecimal number as follows:
0x00 A plain file (not really a flag).
0x01 Hide the file name from directory listings.
0x02 A directory.
0x04 An accociated file (e.g. an Apple resource fork).
0x08 Record format in extended attributes is used.
0x10 No read/execute permission in extended attributes.
0x20 reserved
0x40 reserved
0x80 Not the final entry of a multi extent file.

-N sector
  Quick hack to help examine single session disc files that are to be written to a multi-session disc. The sector number specified is the sector number at which the iso9660 image should be written when send to the cd-writer. Not used for the first session on the disc.
-p Print path table information.
-R Extract information from Rock Ridge extensions (if present) for permissions, file names and ownerships.
-s Print file size infos in multiples of sector size (2048 bytes).
-J Extract information from Joliet extensions (if present) for file names.
-j charset
  Convert Joliet file names (if present) to the supplied charset. See mkisofs(8) for details.
-T sector
  Quick hack to help examine multi-session images that have already been burned to a multi-session disc. The sector number specified is the sector number for the start of the session we wish to display.
-X Extract files from the image and put them into the filesystem. If the -find option is not used, all files are extracted.

The isoinfo program supports to extract all files, even multi extent files (files > 4 GB).

Before extracting files using the -X option, it is recommended to change the current directory to an empty directory in order to prevent to clobber existing files.

-x pathname
  Extract specified file to stdout. The pathname needs to start with a shlash (’/’) and in case of iso9660 names, must match the full pathname of the file inluding the version number (usually ’;1’). If the option -R has been specified and the filesystem carries Rock Ridge attributes, the pathname must match the full Rock Ridge pathname of the file.


The author of the original sources (1993 ... 1998) is Eric Youngdale <> or <> is to blame for these shoddy hacks. Schilling wrote the SCSI transport library and its adaptation layer to the programs and newer parts (starting from 1999) of the utilities, this makes them Copyright (C) 1999-2004 Schilling. Patches to improve general usability would be gladly accepted.


The user interface really sucks.


These utilities are really quick hacks, which are very useful for debugging problems in mkisofs or in an iso9660 filesystem. In the long run, it would be nice to have a daemon that would NFS export a iso9660 image.

The isoinfo program is probably the program that is of the most use to the general user.


These utilities come with the cdrtools package, and the primary download site is and many other mirror sites. Despite the name, the software is not beta.


  This may either hold a device identifier that is suitable to the open call of the SCSI transport library or a label in the file /etc/default/cdrecord.
RSH If the RSH environment is present, the remote connection will not be created via rcmd(3) but by calling the program pointed to by RSH. Use e.g. RSH=/usr/bin/ssh to create a secure shell connection.

Note that this forces the program to create a pipe to the rsh(1) program and disallows the program to directly access the network socket to the remote server. This makes it impossible to set up performance parameters and slows down the connection compared to a root initiated rcmd(3) connection.

RSCSI If the RSCSI environment is present, the remote SCSI server will not be the program /opt/schily/sbin/rscsi but the program pointed to by RSCSI. Note that the remote SCSI server program name will be ignored if you log in using an account that has been created with a remote SCSI server program as login shell.


  Default values can be set for the following options in /etc/default/cdrecord.
  This may either hold a device identifier that is suitable to the open call of the SCSI transport library or a label in the file /etc/default/cdrecord that allows to identify a specific drive on the system.
Any other label
  is an identifier for a specific drive on the system. Such an identifier may not contain the characters ’,’, ’/’, ’@’ or ’:’.

Each line that follows a label contains a TAB separated list of items. Currently, four items are recognized: the SCSI ID of the drive, the default speed that should be used for this drive, the default FIFO size that should be used for this drive and drive specific options. The values for speed and fifosize may be set to -1 to tell the program to use the global defaults. The value for driveropts may be set to "" if no driveropts are used. A typical line may look this way:

teac1= 0,5,0    4       8m      ""

yamaha= 1,6,0   -1      -1      burnfree

This tells the program that a drive named teac1 is at scsibus 0, target 5, lun 0 and should be used with speed 4 and a FIFO size of 8 MB. A second drive may be found at scsibus 1, target 6, lun 0 and uses the default speed and the default FIFO size.


mkisofs(8), cdrecord(1), readcd(1), scg(7), rcmd(3), ssh(1).
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Version 3.02 ISOINFO (8) 2015/11/02

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