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NAME | DESCRIPTION | THE [options] STANZA | THE [defaults] STANZA | THE [problems] STANZA | THE [scratch_files] STANZA | LOGGING | EXAMPLES | FILES | SEE ALSO | COLOPHON |
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e2fsck.conf(5) File Formats Manual e2fsck.conf(5)
e2fsck.conf - Configuration file for e2fsck
e2fsck.conf is the configuration file for e2fsck(8). It controls
the default behavior of e2fsck(8) while it is checking ext2, ext3,
or ext4 file systems.
The e2fsck.conf file uses an INI-style format. Stanzas, or top-
level sections, are delimited by square braces: [ ]. Within each
section, each line defines a relation, which assigns tags to
values, or to a subsection, which contains further relations or
subsections. An example of the INI-style format used by this
configuration file follows below:
[section1]
tag1 = value_a
tag1 = value_b
tag2 = value_c
[section 2]
tag3 = {
subtag1 = subtag_value_a
subtag1 = subtag_value_b
subtag2 = subtag_value_c
}
tag1 = value_d
tag2 = value_e
}
Comments are delimited by a semicolon (';') or a hash ('#')
character at the beginning of the comment, and are terminated by
the end of line character.
Tags and values must be quoted using double quotes if they contain
spaces. Within a quoted string, the standard backslash
interpretations apply: "\n" (for the newline character), "\t" (for
the tab character), "\b" (for the backspace character), and "\\"
(for the backslash character).
The following stanzas are used in the e2fsck.conf file. They will
be described in more detail in future sections of this document.
[options]
This stanza contains general configuration parameters for
e2fsck's behavior.
[defaults]
Contains relations which define the default parameters used
by e2fsck(8). In general, these defaults may be overridden
by command-line options provided by the user.
[problems]
This stanza allows the administrator to reconfigure how
e2fsck handles various file system inconsistencies.
[scratch_files]
This stanza controls when e2fsck will attempt to use
scratch files to reduce the need for memory.
The following relations are defined in the [options] stanza.
allow_cancellation
If this relation is set to a boolean value of true, then if
the user interrupts e2fsck using ^C, and the file system is
not explicitly flagged as containing errors, e2fsck will
exit with an exit status of 0 instead of 32. This setting
defaults to false.
accept_time_fudge
Unfortunately, due to Windows' unfortunate design decision
to configure the hardware clock to tick localtime, instead
of the more proper and less error-prone UTC time, many
users end up in the situation where the system clock is
incorrectly set at the time when e2fsck is run.
Historically this was usually due to some distributions
having buggy init scripts and/or installers that didn't
correctly detect this case and take appropriate
countermeasures. Unfortunately, this is occasionally true
even today, usually due to a buggy or misconfigured
virtualization manager or the installer not having access
to a network time server during the installation process.
So by default, we allow the superblock times to be fudged
by up to 24 hours. This can be disabled by setting
accept_time_fudge to the boolean value of false. This
setting defaults to true.
broken_system_clock
The e2fsck(8) program has some heuristics that assume that
the system clock is correct. In addition, many system
programs make similar assumptions. For example, the UUID
library depends on time not going backwards in order for it
to be able to make its guarantees about issuing universally
unique ID's. Systems with broken system clocks, are well,
broken. However, broken system clocks, particularly in
embedded systems, do exist. E2fsck will attempt to use
heuristics to determine if the time can not be trusted; and
to skip time-based checks if this is true. If this boolean
is set to true, then e2fsck will always assume that the
system clock can not be trusted.
buggy_init_scripts
This boolean relation is an alias for accept_time_fudge for
backwards compatibility; it used to be that the behavior
defined by accept_time_fudge above defaulted to false, and
buggy_init_scripts would enable superblock time field to be
wrong by up to 24 hours. When we changed the default, we
also renamed this boolean relation to accept_time_fudge.
clear_test_fs_flag
This boolean relation controls whether or not e2fsck(8)
will offer to clear the test_fs flag if the ext4 file
system is available on the system. It defaults to true.
defer_check_on_battery
This boolean relation controls whether or not the interval
between file system checks (either based on time or number
of mounts) should be doubled if the system is running on
battery. This setting defaults to true.
indexed_dir_slack_percentage
When e2fsck(8) repacks a indexed directory, reserve the
specified percentage of empty space in each leaf nodes so
that a few new entries can be added to the directory
without splitting leaf nodes, so that the average fill
ratio of directories can be maintained at a higher, more
efficient level. This relation defaults to 20 percent.
inode_count_fullmap
If this boolean relation is true, trade off using memory
for speed when checking a file system with a large number
of hard-linked files. The amount of memory required is
proportional to the number of inodes in the file system.
For large file systems, this can be gigabytes of memory.
(For example a 40TB file system with 2.8 billion inodes
will consume an additional 5.7 GB memory if this
optimization is enabled.) This setting defaults to false.
log_dir
If the log_filename or problem_log_filename relations
contains a relative pathname, then the log file will be
placed in the directory named by the log_dir relation.
log_dir_fallback
This relation contains an alternate directory that will be
used if the directory specified by log_dir is not available
or is not writable.
log_dir_wait
If this boolean relation is true, them if the directories
specified by log_dir or log_dir_fallback are not available
or are not yet writable, e2fsck will save the output in a
memory buffer, and a child process will periodically test
to see if the log directory has become available after the
boot sequence has mounted the requested file system for
reading/writing. This implements the functionality
provided by logsave(8) for e2fsck log files.
log_filename
This relation specifies the file name where a copy of
e2fsck's output will be written. If certain problem
reports are suppressed using the max_count_problems
relation, (or on a per-problem basis using the max_count
relation), the full set of problem reports will be written
to the log file. The filename may contain various percent-
expressions (%D, %T, %N, etc.) which will be expanded so
that the file name for the log file can include things like
date, time, device name, and other run-time parameters.
See the LOGGING section for more details.
max_count_problems
This relation specifies the maximum number of problem
reports of a particular type will be printed to stdout
before further problem reports of that type are squelched.
This can be useful if the console is slow (i.e., connected
to a serial port) and so a large amount of output could end
up delaying the boot process for a long time (potentially
hours).
no_optimize_extents
If this boolean relation is true, do not offer to optimize
the extent tree by reducing the tree's width or depth.
This setting defaults to false.
problem_log_filename
This relation specifies the file name where a log of
problem codes found by e2fsck be written. The filename may
contain various percent-expressions (%D, %T, %N, etc.)
which will be expanded so that the file name for the log
file can include things like date, time, device name, and
other run-time parameters. See the LOGGING section for
more details.
readahead_mem_pct
Use this percentage of memory to try to read in metadata
blocks ahead of the main e2fsck thread. This should reduce
run times, depending on the speed of the underlying storage
and the amount of free memory. There is no default, but
see readahead_kb for more details.
readahead_kb
Use this amount of memory to read in metadata blocks ahead
of the main checking thread. Setting this value to zero
disables readahead entirely. By default, this is set the
size of two block groups' inode tables (typically 4MiB on a
regular ext4 file system); if this amount is more than
1/50th of total physical memory, readahead is disabled.
report_features
If this boolean relation is true, e2fsck will print the
file system features as part of its verbose reporting
(i.e., if the -v option is specified)
report_time
If this boolean relation is true, e2fsck will run as if the
options -tt are always specified. This will cause e2fsck
to print timing statistics on a pass by pass basis for full
file system checks.
report_verbose
If this boolean relation is true, e2fsck will run as if the
option -v is always specified. This will cause e2fsck to
print some additional information at the end of each full
file system check.
The following relations are defined in the [defaults] stanza.
undo_dir
This relation specifies the directory where the undo file
should be stored. It can be overridden via the
E2FSPROGS_UNDO_DIR environment variable. If the directory
location is set to the value none, e2fsck will not create
an undo file.
Each tag in the [problems] stanza names a problem code specified
with a leading "0x" followed by six hex digits. The value of the
tag is a subsection where the relations in that subsection
override the default treatment of that particular problem code.
Note that inappropriate settings in this stanza may cause e2fsck
to behave incorrectly, or even crash. Most system administrators
should not be making changes to this section without referring to
source code.
Within each problem code's subsection, the following tags may be
used:
description
This relation allows the message which is printed when this
file system inconsistency is detected to be overridden.
preen_ok
This boolean relation overrides the default behavior
controlling whether this file system problem should be
automatically fixed when e2fsck is running in preen mode.
max_count
This integer relation overrides the max_count_problems
parameter (set in the options section) for this particular
problem.
no_ok This boolean relation overrides the default behavior
determining whether or not the file system will be marked
as inconsistent if the user declines to fix the reported
problem.
no_default
This boolean relation overrides whether the default answer
for this problem (or question) should be "no".
preen_nomessage
This boolean relation overrides the default behavior
controlling whether or not the description for this file
system problem should be suppressed when e2fsck is running
in preen mode.
no_nomsg
This boolean relation overrides the default behavior
controlling whether or not the description for this file
system problem should be suppressed when a problem forced
not to be fixed, either because e2fsck is run with the -n
option or because the force_no flag has been set for the
problem.
force_no
This boolean option, if set to true, forces a problem to
never be fixed. That is, it will be as if the user problem
responds 'no' to the question of 'should this problem be
fixed?'. The force_no option even overrides the -y option
given on the command-line (just for the specific problem,
of course).
not_a_fix
This boolean option, it set to true, marks the problem as
one where if the user gives permission to make the
requested change, it does not mean that the file system had
a problem which has since been fixed. This is used for
requests to optimize the file system's data structure, such
as pruning an extent tree.
The following relations are defined in the [scratch_files] stanza.
directory
If the directory named by this relation exists and is
writeable, then e2fsck will attempt to use this directory
to store scratch files instead of using in-memory data
structures.
numdirs_threshold
If this relation is set, then in-memory data structures
will be used if the number of directories in the file
system are fewer than amount specified.
dirinfo
This relation controls whether or not the scratch file
directory is used instead of an in-memory data structure
for directory information. It defaults to true.
icount This relation controls whether or not the scratch file
directory is used instead of an in-memory data structure
when tracking inode counts. It defaults to true.
E2fsck has the facility to save the information from an e2fsck run
in a directory so that a system administrator can review its
output at their leisure. This allows information captured during
the automatic e2fsck preen run, as well as a manually started
e2fsck run, to be saved for posterity. This facility is
controlled by the log_filename, log_dir, log_dir_fallback, and
log_dir_wait relations in the [options] stanza.
The filename in log_filename may contain the following percent-
expressions that will be expanded as follows.
%d The current day of the month
%D The current date; this is a equivalent of %Y%m%d
%h The hostname of the system.
%H The current hour in 24-hour format (00..23)
%m The current month as a two-digit number (01..12)
%M The current minute (00..59)
%N The name of the block device containing the file system,
with any directory pathname stripped off.
%p The pid of the e2fsck process
%s The current time expressed as the number of seconds since
1970-01-01 00:00:00 UTC
%S The current second (00..59)
%T The current time; this is equivalent of %H%M%S
%u The name of the user running e2fsck.
%U This percent expression does not expand to anything, but it
signals that any following date or time expressions should
be expressed in UTC time instead of the local timezone.
%y The last two digits of the current year (00..99)
%Y The current year (i.e., 2012).
The following recipe will prevent e2fsck from aborting during the
boot process when a file system contains orphaned files. (Of
course, this is not always a good idea, since critical files that
are needed for the security of the system could potentially end up
in lost+found, and starting the system without first having a
system administrator check things out may be dangerous.)
[problems]
0x040002 = {
preen_ok = true
description = "@u @i %i. "
}
The following recipe will cause an e2fsck logfile to be written to
the directory /var/log/e2fsck, with a filename that contains the
device name, the hostname of the system, the date, and time: e.g.,
"e2fsck-sda3.server.INFO.20120314-112142". If the directory
containing /var/log is located on the root file system which is
initially mounted read-only, then the output will be saved in
memory and written out once the root file system has been
remounted read/write. To avoid too much detail from being
written to the serial console (which could potentially slow down
the boot sequence), only print no more than 16 instances of each
type of file system corruption.
[options]
max_count_problems = 16
log_dir = /var/log/e2fsck
log_filename = e2fsck-%N.%h.INFO.%D-%T
log_dir_wait = true
/etc/e2fsck.conf
The configuration file for e2fsck(8).
e2fsck(8)
This page is part of the e2fsprogs (utilities for ext2/3/4
filesystems) project. Information about the project can be found
at ⟨http://e2fsprogs.sourceforge.net/⟩. It is not known how to
report bugs for this man page; if you know, please send a mail to
man-pages@man7.org. This page was obtained from the project's
upstream Git repository
⟨git://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git⟩ on
2025-08-11. (At that time, the date of the most recent commit
that was found in the repository was 2025-07-31.) If you discover
any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page,
or you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a
mail to man-pages@man7.org
E2fsprogs version 1.47.3 July 2025 e2fsck.conf(5)
Pages that refer to this page: e2fsck(8)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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