.\" -*- nroff -*-
.\" Copyright 2008 by Theodore Ts'o.  All Rights Reserved.
.\" This file may be copied under the terms of the GNU Public License.
.\"
.TH E2UNDO 8 "September 2019" "E2fsprogs version 1.45.4"
.SH NAME
e2undo \- Replay an undo log for an ext2/ext3/ext4 filesystem
.SH SYNOPSIS
.B e2undo
[
.B \-f
]
[
.B \-h
]
[
.B \-n
]
[
.B \-o
.I offset
]
[
.B \-v
]
[
.B \-z
.I undo_file
]
.I undo_log device
.SH DESCRIPTION
.B e2undo
will replay the undo log
.I undo_log
for an ext2/ext3/ext4 filesystem found on
.IR device .
This can be
used to undo a failed operation by an e2fsprogs program.
.SH OPTIONS
.TP
.B \-f
Normally,
.B e2undo
will check the filesystem superblock to make sure the undo log matches
with the filesystem on the device.  If they do not match,
.B e2undo
will refuse to apply the undo log as a safety mechanism.  The
.B \-f
option disables this safety mechanism.
.TP
.B \-h
Display a usage message.
.TP
.B \-n
Dry-run; do not actually write blocks back to the filesystem.
.TP
.BI \-o " offset"
Specify the filesystem's
.I offset
(in bytes) from the beginning of the device or file.
.TP
.B \-v
Report which block we're currently replaying.
.TP
.BI \-z " undo_file"
Before overwriting a file system block, write the old contents of the block to
an undo file.  This undo file can be used with e2undo(8) to restore the old
contents of the file system should something go wrong.  If the empty string is
passed as the undo_file argument, the undo file will be written to a file named
e2undo-\fIdevice\fR.e2undo in the directory specified via the
\fIE2FSPROGS_UNDO_DIR\fR environment variable.

WARNING: The undo file cannot be used to recover from a power or system crash.
.SH AUTHOR
.B e2undo
was written by Aneesh Kumar K.V. (aneesh.kumar@linux.vnet.ibm.com)
.SH AVAILABILITY
.B e2undo
is part of the e2fsprogs package and is available from
http://e2fsprogs.sourceforge.net.
.SH SEE ALSO
.BR mke2fs (8),
.BR tune2fs (8)