---
name: "cryptsetup-fvault2Dump"
section: "8"
platform: "linux"
package: "cryptsetup"
version: "2.8.8-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/cryptsetup-fvault2Dump"
---

# cryptsetup-fvault2Dump(8)

dump the header information of a FVAULT2 (FileVault2 compatible) device

## NAME

cryptsetup-fvault2Dump - dump the header information of a FVAULT2 (FileVault2 compatible) device

## SYNOPSIS

**cryptsetup** *fvault2Dump* **\[\<options\>\] \<device\>**

## DESCRIPTION

*Dump the header information of a FVAULT2 (FileVault2 compatible) device.*

*If the --dump-volume-key option is used, the FVAULT2 device volume key is dumped instead of header information.* *You have to provide a password or keyfile to dump the volume key.*

*Beware that the volume key can be used to decrypt the data stored in the container without a passphrase.* *This means that if the volume key is compromised, the whole device has to be erased to prevent further access.* *Use this option carefully.*

**\<options\>** *can be \[--dump-volume-key, --volume-key-file, --key-file, --keyfile-offset, --keyfile-size, --timeout\].*

## OPTIONS

**--batch-mode***,* **-q**

*Suppresses all confirmation questions.* *Use with care!*

*If the --verify-passphrase option is not specified, this option also switches off the passphrase verification.*

**--debug** *or* **--debug-json**

*Run in debug mode with full diagnostic logs.* *Debug output lines are always prefixed by* **#***.*

*If --debug-json is used, additional LUKS2 JSON data structures are printed.*

**--dump-volume-key***, --dump-master-key (OBSOLETE alias)*

*Print the volume key in the displayed information.* *Use with care, as the volume key can be used to bypass the passphrases, see also option --volume-key-file.*

**--help***,* **-?**

*Show help text and default parameters.*

**--key-file***,* **-d** *file*

*Read the passphrase from the file.*

*If the name given is "-", then the passphrase will be read from stdin.* *In this case, reading will not stop at newline characters.*

*See section NOTES ON PASSPHRASE PROCESSING in* **cryptsetup***(8) for more information.*

**--keyfile-offset** *value*

*Skip value bytes at the beginning of the key file.*

**--keyfile-size***,* **-l** *value*

*Read a maximum of value bytes from the key file.* *The default is to read the whole file up to the compiled-in maximum that can be queried with --help.* *Supplying more data than the compiled-in maximum aborts the operation.*

*This option is useful to cut trailing newlines, for example.* *If --keyfile-offset is also given, the size count starts after the offset.*

**--timeout***,* **-t** *seconds*

*The number of seconds to wait before a timeout on passphrase input via terminal.* *It is relevant every time a passphrase is asked.* *It has no effect if used in conjunction with --key-file.*

*This option is useful when the system should not stall if the user does not input a passphrase, e.g., during boot.* *The default is a value of 0 seconds, which means to wait forever.*

- **--usage**

  *Show short option help.*

**--version***,* **-V**

*Show the program version.*

**--volume-key-file** *file, --master-key-file file (OBSOLETE alias)*

*Use a volume key stored in a file.*

*The volume key is stored in a file instead of being printed out to standard output.*

## REPORTING BUGS

*Report bugs at* *cryptsetup mailing list \<cryptsetup@lists.linux.dev\>* *or in* *Issues project section \<https://gitlab.com/cryptsetup/cryptsetup/-/issues/new\>.*

*Please attach the output of the failed command with --debug option added.*

## SEE ALSO

*Cryptsetup FAQ \<https://gitlab.com/cryptsetup/cryptsetup/wikis/FrequentlyAskedQuestions\>*

**cryptsetup***(8),* **integritysetup***(8) and* **veritysetup***(8)*

## CRYPTSETUP

*Part of* *cryptsetup project \<https://gitlab.com/cryptsetup/cryptsetup/\>.*