---
name: "etdump"
section: "1"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/etdump"
---

# etdump(1)

dump ISO-9660 El Torito boot catalog information

## NAME

**etdump** – dump ISO-9660 El Torito boot catalog information

## SYNOPSIS

**etdump** \[**-f** *format*\] \[**-o** *file*\] *file ...*

## DESCRIPTION

This program reads El Torito boot catalog information from an ISO-9660 image and outputs it in various formats. It can be used to check the catalog in an image or to output catalog data in a format that can be used by other tools such as shell scripts.

Supported options are:

- **-f** *format* \| **--format** *format*

  Select the output format. Supported output formats are:

  - **text**

    Human-readable text (default)

  - **shell**

    Each boot entry is emitted as a string suitable for passing to a sh-compatible eval command. The variables emitted are:

    - et\_platform

      The platform ID from the section header. Set to 'default' for the initial (default) entry.

    - et\_system

      The system ID from the boot entry.

    - et\_lba

      The starting LBA (2048-byte blocks) of the boot image.

    - et\_sectors

      The number of sectors (512-byte sectors) that comprise the boot image.

- **-o** *file* \| **--output** *file*

  Write output to *file*. If ‘-’ is specified then standard out is used.

## EXAMPLES

To see what entries are in a given boot catalog run **etdump** passing the filename of the image as an argument like so:

```
% etdump bootonly.iso
Image in bootonly.iso
Default entry
	System i386
	Start LBA 420 (0x1a4), sector count 4 (0x4)
	Media type: no emulation
Section header: efi, final
	Section entry
		System i386
		Start LBA 20 (0x14), sector count 1600 (0x640)
		Media type: no emulation
```

To use the output in a shell script a for loop can be used to iterate over the entries returned using eval:

```
for entry in `etdump --format shell bootonly.iso`; do
	eval $entry
	echo $et_platform $et_system $et_lba $et_sectors
done
```

## SEE ALSO

[cd9660(4)](/cd9660/4.md)

## HISTORY

The **etdump** utility first appeared in FreeBSD 11.2