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<H1>E2UNDO</H1>
Section: Maintenance Commands (8)<BR>Updated: January 2020<BR><A HREF="#index">Index</A>
<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
<A NAME="lbAB">&nbsp;</A>
<H2>NAME</H2>
e2undo - Replay an undo log for an ext2/ext3/ext4 filesystem
<A NAME="lbAC">&nbsp;</A>
<H2>SYNOPSIS</H2>
<B>e2undo</B>
[
<B>-f</B>
]
[
<B>-h</B>
]
[
<B>-n</B>
]
[
<B>-o</B>
<I>offset</I>
]
[
<B>-v</B>
]
[
<B>-z</B>
<I>undo_file</I>
]
<I>undo_log device</I>
<A NAME="lbAD">&nbsp;</A>
<H2>DESCRIPTION</H2>
<B>e2undo</B>
will replay the undo log
<I>undo_log</I>
for an ext2/ext3/ext4 filesystem found on
<I>device</I>.
This can be
used to undo a failed operation by an e2fsprogs program.
<A NAME="lbAE">&nbsp;</A>
<H2>OPTIONS</H2>
<DL COMPACT>
<DT id="1"><B>-f</B>
<DD>
Normally,
<B>e2undo</B>
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</B>
will refuse to apply the undo log as a safety mechanism. The
<B>-f</B>
option disables this safety mechanism.
<DT id="2"><B>-h</B>
<DD>
Display a usage message.
<DT id="3"><B>-n</B>
<DD>
Dry-run; do not actually write blocks back to the filesystem.
<DT id="4"><B>-o</B><I> offset</I>
<DD>
Specify the filesystem's
<I>offset</I>
(in bytes) from the beginning of the device or file.
<DT id="5"><B>-v</B>
<DD>
Report which block we're currently replaying.
<DT id="6"><B>-z</B><I> undo_file</I>
<DD>
Before overwriting a file system block, write the old contents of the block to
an undo file. This undo file can be used with <A HREF="/cgi-bin/man/man2html?8+e2undo">e2undo</A>(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-<I>device</I>.e2undo in the directory specified via the
<I>E2FSPROGS_UNDO_DIR</I> environment variable.
<P>
WARNING: The undo file cannot be used to recover from a power or system crash.
</DL>
<A NAME="lbAF">&nbsp;</A>
<H2>AUTHOR</H2>
<B>e2undo</B>
was written by Aneesh Kumar K.V. (<A HREF="mailto:aneesh.kumar@linux.vnet.ibm.com">aneesh.kumar@linux.vnet.ibm.com</A>)
<A NAME="lbAG">&nbsp;</A>
<H2>AVAILABILITY</H2>
<B>e2undo</B>
is part of the e2fsprogs package and is available from
<A HREF="http://e2fsprogs.sourceforge.net.">http://e2fsprogs.sourceforge.net.</A>
<A NAME="lbAH">&nbsp;</A>
<H2>SEE ALSO</H2>
<B><A HREF="/cgi-bin/man/man2html?8+mke2fs">mke2fs</A></B>(8),
<B><A HREF="/cgi-bin/man/man2html?8+tune2fs">tune2fs</A></B>(8)
<P>
<P>
<HR>
<A NAME="index">&nbsp;</A><H2>Index</H2>
<DL>
<DT id="7"><A HREF="#lbAB">NAME</A><DD>
<DT id="8"><A HREF="#lbAC">SYNOPSIS</A><DD>
<DT id="9"><A HREF="#lbAD">DESCRIPTION</A><DD>
<DT id="10"><A HREF="#lbAE">OPTIONS</A><DD>
<DT id="11"><A HREF="#lbAF">AUTHOR</A><DD>
<DT id="12"><A HREF="#lbAG">AVAILABILITY</A><DD>
<DT id="13"><A HREF="#lbAH">SEE ALSO</A><DD>
</DL>
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