eatmydata(1)eatmydata(1)NAMEeatmydata - transparently disable fsync() and other data-to-disk syn‐
chronization calls
SYNOPSISeatmydata [--] command [ command arguments ... ]
DESCRIPTIONeatmydata runs a command in the environment where data-to-disk synchro‐
nization calls (like fsync(), fdatasync(), sync(), msync() and open()
O_SYNC / O_DSYNC flags) have no effect. LD_PRELOAD library libeatmydata
overrides respective C library calls with custom functions that don't
trigger synchronization but return success nevertheless.
You may use eatmydata in two ways. In normal mode, just execute eatmy‐
data directly and pass a command-to-be-run and its arguments via com‐
mand line. In order to use symlink mode, create a symlink to
/usr/bin/eatmydata with the filename (a.k.a basename) of another pro‐
gram in the PATH and execute eatmydata via that symlink. Then eatmydata
will find that program in the PATH and run it in the libeatmydata envi‐
ronment repassing all command line options.
OPTIONS
Please note that eatmydata does not process any command line options in
symlink mode. All command line options will be repassed to the underly‐
ing executable as-is.
command
The command to execute. It may be either a full path or the name
of the command in PATH. In case command cannot be found in PATH,
eatmydata will fail.
command arguments
Arbitrary number of arguments to pass to the command being exe‐
cuted.
-- Optional command separator for compatibility with similar utili‐
ties. Ignored at the moment.
EXAMPLES
Given PATH is /usr/bin and both /usr/bin/aptitude and /usr/bin/eatmy‐
data are installed, the following:
$ ln -s /usr/bin/eatmydata ./aptitude
$ ./aptitude moo
is equivalent to:
$ eatmydata-- aptitude moo
Therefore, you may use symlink mode to automatically run specific pro‐
grams in the libeatmydata environment whenever you run them from PATH.
For example, given standard PATH settings, just do:
# ln -s /usr/bin/eatmydata /usr/local/bin/aptitude
and enjoy sync-free aptitude system-wide.
CAVEAT
When using eatmydata with setarch (including alias such as linux32), or
anyway with chroots with a different architectures than the host's,
make sure to install the matching architecture of libeatmydata1 both in
the setarch environment and host's.
Trying to load libeatmydata manually (without using the wrapper script)
and using it through a chroot, especially if the eatmydata version dif‐
fer between outside and inside, is probably going to fail do the dif‐
ferent position of the library on the file system.
The safest way to manually load libeatmydata is by setting the follow‐
ing two environment variables (shell syntax):
LD_LIBRARY_PATH=${LD_LIBRARY_PATH:+"$LD_LIBRARY_PATH:"}/usr/lib/libeatmydata
LD_PRELOAD=${LD_PRELOAD:+"$LD_PRELOAD "}libeatmydata.so
These two variables accounts the case of a Debian Jessie host with a
Debian Wheezy chroot, where the position of the library changed.
November 2014 eatmydata(1)
