Linux and UNIX Man Pages

Linux & Unix Commands - Search Man Pages

ureadahead(8) [linux man page]

ureadahead(8)						      System Manager's Manual						     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 rotational 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 out- put 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 contend with other pro- cesses 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 location, 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/ureadahead and are named mountpoint.pack When tracing, these will be automatically generated. FILES
/var/lib/ureadahead/pack AUTHOR
Written by Scott James Remnant <scott@netsplit.com> BUGS
Report bugs at <https://launchpad.net/ubuntu/+source/ureadahead/+bugs> 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 PARTICU- LAR PURPOSE. SEE ALSO
readahead(2) ureadahead 2009-09-29 ureadahead(8)

Check Out this Related Man Page

GIT-INDEX-PACK(1)						    Git Manual							 GIT-INDEX-PACK(1)

NAME
git-index-pack - Build pack index file for an existing packed archive SYNOPSIS
git index-pack [-v] [-o <index-file>] <pack-file> git index-pack --stdin [--fix-thin] [--keep] [-v] [-o <index-file>] [<pack-file>] DESCRIPTION
Reads a packed archive (.pack) from the specified file, and builds a pack index file (.idx) for it. The packed archive together with the pack index can then be placed in the objects/pack/ directory of a git repository. OPTIONS
-v Be verbose about what is going on, including progress status. -o <index-file> Write the generated pack index into the specified file. Without this option the name of pack index file is constructed from the name of packed archive file by replacing .pack with .idx (and the program fails if the name of packed archive does not end with .pack). --stdin When this flag is provided, the pack is read from stdin instead and a copy is then written to <pack-file>. If <pack-file> is not specified, the pack is written to objects/pack/ directory of the current git repository with a default name determined from the pack content. If <pack-file> is not specified consider using --keep to prevent a race condition between this process and git repack. --fix-thin Fix a "thin" pack produced by git pack-objects --thin (see git-pack-objects(1) for details) by adding the excluded objects the deltified objects are based on to the pack. This option only makes sense in conjunction with --stdin. --keep Before moving the index into its final destination create an empty .keep file for the associated pack file. This option is usually necessary with --stdin to prevent a simultaneous git repack process from deleting the newly constructed pack and index before refs can be updated to use objects contained in the pack. --keep=<msg> Like --keep create a .keep file before moving the index into its final destination, but rather than creating an empty file place <msg> followed by an LF into the .keep file. The <msg> message can later be searched for within all .keep files to locate any which have outlived their usefulness. --index-version=<version>[,<offset>] This is intended to be used by the test suite only. It allows to force the version for the generated pack index, and to force 64-bit index entries on objects located above the given offset. --strict Die, if the pack contains broken objects or links. NOTE
Once the index has been created, the list of object names is sorted and the SHA1 hash of that list is printed to stdout. If --stdin was also used then this is prefixed by either "pack ", or "keep " if a new .keep file was successfully created. This is useful to remove a .keep file used as a lock to prevent the race with git repack mentioned above. GIT
Part of the git(1) suite Git 1.7.10.4 11/24/2012 GIT-INDEX-PACK(1)
Man Page