man ureadahead Command

Man page for apt-get ureadahead Command

Man Page for ureadahead in Linux

Ubuntu Man Command : man ureadahead

Man Ureadahead  Command

This tutorial shows the man page for man ureadahead in linux.

Open terminal with 'su' access and type the command as shown below:
man ureadahead

Result of the Command Execution shown below:

ureadahead(8)                                                    ureadahead(8)



NAME
ureadahead Read files in advance during boot

SYNOPSIS
ureadahead [OPTIONS]... [PACK]

DESCRIPTION
ureadahead (uber readahead) is used during boot to read files in
advance of when they are needed such that they are already in the page
cache, improving boot performance.

When started without any arguments, it checks for the existance and age
of the default pack file /var/lib/ureadahead/pack, and if not present
or older than a month, will discard it and retrace the boot sequence.
The pack will then contain information about the files opened during
boot, and the blocks that were in memory at the completion of the boot.

If the file exists and is newer than a month old, or an alternate PACK
path is given on the command line, the files listed in the pack are
opened and the blocks read into the page cache using the readahead(2)
system call.

Pack files are automatically optimised for Solid State Disks or rota
tional Hard Drives, depending on which you have.

OPTIONS
verbose
May be used to report on ureadahead's operation. In particular,
this causes information about the size of the pack file to be
output when reading and a complete dump of the contents of the
pack file after tracing.

daemon
Places ureadahead into the background once the pack file has
been read, or once tracing has been enabled.

This is ignored when reading on rotational hard drives, since
it's important for performance reasons not to content with other
processes for I/O.

force trace
Discards all pack files and forces re tracing.

timeout=SECONDS
Normally when tracing, ureadahead will wait for a TERM or INT
signal before concluding and generating the pack file. This
option instead sets a timeout after which tracing is terminated.

dump Dump the contents of the pack file to standard output in a
pretty format, does not trace or read the contents into memory.

sort=SORT
Used with dump to sort the output.

The default is open, which is the order that the files will be
opened. path sorts by path name, disk sorts by on disk loca
tion, and size sorts by the amount of data that will be read for
that file.

OTHER MOUNT POINTS
PACK need not be the filename of a pack, instead it may be the name of
a mount point (or indeed any non file within the filesystem), in which
case the pack for that device is read instead. This allows ureadahead
to be called in the style ureadahead /usr for filesystems split across
multiple devices.

Pack files for these other devices are also stored under /var/lib/ure
adahead and are named mountpoint.pack

When tracing, these will be automatically generated.

FILES
/var/lib/ureadahead/pack

AUTHOR
Written by Scott James Remnant

BUGS
Report bugs at

COPYRIGHT
Copyright (C) 2009 Canonical Ltd.

This is free software; see the source for copying conditions. There is
NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE.

SEE ALSO
readahead(2)



ureadahead 2009 09 29 ureadahead(8)


Related Topics

Apt Get Commands