EA descriptions

What do all of these attributes mean?


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Descriptions for what some EA mean

General information

The below tables do not take into account all EA for the system. They are designed as a guide to the libferris 1.1.40+ EA. Once an EA is in the system it rarely changes so these tables should be suitable for future versions of libferris.

Some EA generated from libextractor, native kernel EA and RDF sources are impossible to fully enumerate here in a timely manner. Also when you mount a relational database or XML file/database attributes are created to export information of interest. For example a relational database when mounted shows its rows as files and its columns as EA on those files. One should keep this in mind and consider the tables as a reference to only some of the EAs in the system.

Another section that is only briefly mentioned is the emblem EAs. This is because each user is expected to have their own emblem collection with their own partial ordering over their emblems. See the ADCS03 paper in the papers section of the site for a starting guide to emblems and one of their considered uses.

The EAs everyone should be aware of

This table describes important EA.

Important EA
EA namedescription
as-rdfAll the EA for the file presented as an RDF/XML document
as-xmlAll the EA for the file presented as an XML document
as-textA plain text representation of the file. May loose formatting information.
contentThe file's contents.
urlThe file's URL. eg. file://tmp/foobar.tar
pathPath for this file. eg. /tmp/foobar.tar
name-extensionFile's extension. eg. tar
atimeTime of last access. In seconds since UNIX epoch (1/Jan/1970)
atime-ctimectime(3) formated string showing the atime EA
atime-displayatime EA shown in a user selectable presentation format
atime-day-granularityatime EA rounded down to nearest day
atime-month-granularityatime EA rounded down to nearest month
atime-year-granularityatime EA rounded down to nearest year
ctimeSame collection of EA as for atime
ferris-current-timeSame collection of EA as for atime
mtimeSame collection of EA as for atime
attribute-countTotal number of EAs for this file
ea-namesA list of the names of all EA for this file.
recommended-eaThe names of EA which should be interesting to the user for this file.
recommended-ea-shortA shortened version of recommended-ea
recommended-ea-unionThe union of recommended-ea for all files/dirs in a directory.
treeiconThe URL of an image that is appropriate for this file.
emblem:listA complete listing of all emblems as a comma seperated list
emblem:list-uiA listing of all important emblems as a comma seperated list
emblem:x-mtimeThe last time data about the "x" emblem was changed. This also has the "-ctime", "-display" EA for accessing this time in a formatted manner.
emblem:has-xIs this file associated with emblem "x"
emblem:has-fuzzy-xBased on supervised machine learning should this file be associated with emblem "x"
is-active-viewWill this directory update itself to reflect changes made by other apps
is-animation-objectIs the MIME major type animation
is-audio-objectIs the MIME major type audio
is-image-objectIs the MIME major type image
is-source-objectIs this file source code
is-dirUnderlying kernel object is a directory
is-fileUnderlying kernel object is a file
language-humanWhat is the human language for this file. eg. english
mimetypeMIME type of the file perhaps based on quick guessing
mimetype-from-contentMIME type of the file definately based on inspecting file bytes.
is-nativeUsing kernel based filesystem (a file:// URL)
is-remoteIs this file remote to this machine
sizeSize of the file
size-human-readableSize of the file in human readable format (similar to ls -lh)
md2Checksums calculated from the file's byte content when the EA are read.
mdc2Checksums calculated from the file's byte content when the EA are read.
md5Checksums calculated from the file's byte content when the EA are read.
sha1Checksums calculated from the file's byte content when the EA are read.




Native file:// EAs

This table describes various EA which are likely to be only found for file:// URLs. For file:// URLs there is also a "dontfollow-" prefixed version of some EA which present the values found from a lstat(2) call. By default the stat(2) call values are shown which means that the EA values for link files are for the link target not the link itself.

native file:// metadata
EA namedescription
devicest_dev from stat(2)
device-typest_rdev from stat(2)
filesystem-filetypestring describing the type of this file.
force-passive-viewHas the user elected not to monitor this directory for changes
fs-available-block-countf_bavail from statfs(2)
fs-block-countf_blocks from statfs(2)
fs-block-sizef_bsize from statfs(2)
fs-file-name-length-maximumf_namelen from statfs(2)
fs-file-nodes-freef_ffree from statfs(2)
fs-file-nodes-totalf_files from statfs(2)
fs-free-block-countf_bfree from statfs(2)
fs-idf_fsid from statfs(2)
fs-nameName of filesystem this file is on. eg. ext2
fs-typef_type from statfs(2)
group-executableFile mode has g+x
group-readableFile mode has g+r
group-writableFile mode has g+w
group-owner-nameName of group owning file
group-owner-numberNumber of group owning file
hard-link-countst_nlink from stat(2)
has-holesDoes the file contain holes?
has-subcontexts-guessA quick guess if this object has children
has-valid-signatureIs there a valid digital signature for this file
inodeINode for this file
is-linkUnderlying kernel object is a link
is-specialUnderlying kernel object is a special object
modest_mode from stat(2)
protection-lsmode EA formatted for ls(1) display
other-executableFile mode has o+x
other-readableFile mode has o+r
other-writableFile mode has o+w
readableCan the user reading this EA read the file?
writableCan the user reading this EA write to the file?
realpathFor links returns the realpath(3) string
runableCan the user reading this EA run this file?
deletableCan the user reading this EA delete this file? eg. A directory with +wx permissions set for other implicitly allows all users to delete any file in that directory.
user-executableFile mode has u+x
user-readableFile mode has u+r
user-writableFile mode has u+w
user-owner-nameName of owner of this file
user-owner-numberNumber for owner of this file
block-countNumber of disk blocks occupied by this file
block-sizeSize of the disk blocks used by this file


Image related EAs

These will be likely available for many image formats depending on what support for images your build of libferris was created with. Note that some EAs such as the EXIF and XMP generated EAs are not described here but have similar names to the attributes of the underlying specification where spaces and underscores are replaced with "-".

Image EA
EA namedescription
aspect-ratioImage data's width to height ratio
depthNumber of bits per pixel
depth-per-colorNumber of bits per colour
gammaGamma adjustment for this image
has-alphatrue if there is an alpha channel
heightHeight of the image
widthWidth of the image
rgba-32bppDecoded image data in RGBA 32 bit per pixel format
exif:has-thumbnailIs there an EXIF thumbnal in this image
exif:thumbnail-updateEchoing 1 into this will recreate the EXIF thumbnail
exif:thumbnail-heightEXIF thumbnal height
exif:thumbnail-widthEXIF thumbnal width
exif:thumbnail-rgba-32bppDecoded thumbnail image. Same format as rgba-32bpp
exif:...All EXIF tag metadata is exported with logical EA names
been-downloadedHas this image been downloaded from the digital camera already
deletableCan we delete this image from the digital camera.


Audio related EAs

These will be available on some or all of your audio files providing interesting metadata about them.

Audio EA
EA namedescription
a52-bit-ratebit rate of an ac3/a52 audio stream. The a52-* information is also provided for mpeg2 files that have such audio embedded in them.
a52-sample-rate
a52-has-baseIs there a base channel
a52-frame-length
a52-channelsNumber of audio channels
a52-channels-frontNumber of 'front' audio channels
a52-channels-rear
titleID3: track title
artistID3: artist for track
albumID3: Name of album containing track
yearID3: Year the album/single containing this track was released
trackID3: Number of this track from its album. eg. 7


Video related EAs

These will be available on some or all of your video files providing interesting metadata about them.

Video EA
EA namedescription
pgmpipeA stream of YUV images containing the decoded images from the video file
widthWidth of the video file
heightHeight of the video file
frame-countnumber of video frames in file
durationDuration of video in seconds
aspect-ratioRatio of width to height of how video should be shown
letterboxIs video letterboxed


EA which relate to branch filesystems

Branch filesystems present information about a file via a virtual filesystem. For example for a digitally signed file the people who have signed the file, when they signed it and if the signature is valid are all expressed via a branch filesystem.

EA which relate to branch filesystems
EA namedescription
associated-branchesList of all "branchfs-" EA for this file
associated-branches-urlURL for a filesystem showing all "branchfs-" EA for this file
branchfs-attributesURL which will show this file's EA as directory containing files
branchfs-medallionsURL which will show this file's emblems as a directory containing files
branchfs-parentsURL which will show All the parents of this file
branchfs-signaturesURL which will show the people who have signed this file and when


RPM EA

These EAs are available on RPM based Linux distributions. They provide information about each file that is taken from the rpm database on the machine. See rpm(8) for more information.

RPM EA
EA namedescription
rpm-info-url
rpm-is-config
rpm-is-doc
rpm-is-ghost
rpm-is-license
rpm-is-pubkey
rpm-is-readme
rpm-packageRPM package which installed this file
rpm-releaserelease of rpm-package that installed this file
rpm-verify-device
rpm-verify-group
rpm-verify-md5true if the file has not been changed since it was installed.
rpm-verify-mode
rpm-verify-mtime
rpm-verify-owner
rpm-verify-size
rpm-version

Miscellaneous EA which are very handy for specific use cases

These have been added to the system over time usually to solve specific problems.

Miscellaneous EA
EA namedescription
parent-nameName of the parent dir. eg. for /tmp/foobar.tar, parent-name=tmp
download-if-mtime-sinceBefore reading a document from HTTP/FTP a time can be written to this EA and an exception will be thrown if the remove document has not been modified since the written time. Also has the same collection of EA as for atime
size-cdrom-countNumber of 700Mb CDROMs required for this file
size-dvd-countNumber of 4.4Gb DVDs required for this file
recursive-subcontext-*The "recursive-" prefix EA return similar information for a whole tree. They can be slow to read as a full traversal of all children may be required.
subcontext-*The "subcontext-" EA return information about direct children.