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rewrite so it's understandable without knowing about the related command-line options

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Joey Hess 2015-06-16 20:17:17 -04:00
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@ -39,8 +39,8 @@ files that `git annex get --auto` will want to get, and `git annex find
will want to drop. will want to drop.
The expressions are very similar to the matching options documented The expressions are very similar to the matching options documented
on the [[git-annex]] man page. At the command line, you can use those on the [[git-annex-matching-options]] man page.
options in commands like this: At the command line, you can use those options in commands like this:
git annex get --include='*.mp3' --and -'(' --not --largerthan=100mb -')' git annex get --include='*.mp3' --and -'(' --not --largerthan=100mb -')'
@ -48,152 +48,208 @@ The equivalent preferred content expression looks like this:
include=*.mp3 and (not largerthan=100mb) include=*.mp3 and (not largerthan=100mb)
So, just remove the dashes, basically. However, there are some differences So, just remove the dashes, basically. But, there are some differences
from the command line options to keep in mind: between the command line options and expressions, so see the documentation
below to get the full story.
### difference: file matching ## expressions
While --include and --exclude match files relative to the current * `include=glob` and `exclude=glob`
directory, preferred content expressions always match files relative to the
top of the git repository.
For example, suppose you put files into `archive` directories Match files to include, or exclude.
when you're done with them. Then you could configure your laptop to prefer
to not retain those files, like this: While --include=glob and --exclude=glob match files relative to the current
directory, preferred content expressions always match files relative to the
top of the git repository.
For example, suppose you put files into `archive` directories
when you're done with them. Then you could configure your laptop to prefer
to not retain those files, like this:
exclude=*/archive/* exclude=*/archive/*
### difference: no "in=" * `copies=number`
Preferred content expressions have no direct equivalent to `--in`. Matches only files that git-annex believes to have the specified number
of copies, or more. Note that it does not check remotes to verify that
the copies still exist.
Often, it's best to add repositories to groups, and match against To decide if content should be dropped, git-annex evaluates the preferred
the groups in a preferred content expression. So rather than content expression under the assumption that the content has *already* been
`--in=usbdrive`, put all the USB drives into a "transfer" group, dropped. If the content would not be wanted then, the drop can be done.
and use "copies=transfer:1" So, for example, `copies=2` in a preferred content expression lets
content be dropped only when there are currently 3 copies of it, including
the repo it's being dropped from. This is different than running `git annex
drop --copies=2`, which will drop files that currently have 2 copies.
### difference: dropping * `copies=trustlevel:number`
To decide if content should be dropped, git-annex evaluates the preferred Matches only files that git-annex believes have the specified number
content expression under the assumption that the content has *already* been copies, on remotes with the specified trust level. For example,
dropped. If the content would not be wanted then, the drop can be done. `copies=trusted:2`
So, for example, `copies=2` in a preferred content expression lets
content be dropped only when there are currently 3 copies of it, including
the repo it's being dropped from. This is different than running `git annex
drop --copies=2`, which will drop files that currently have 2 copies.
### difference: "present" To match any trust level at or higher than a given level,
use 'trustlevel+'. For example, `--copies=semitrusted+:2`
There's a special "present" keyword you can use in a preferred content * `copies=groupname:number`
expression. This means that content is wanted if it's present,
and not otherwise. This leaves it up to you to use git-annex manually Matches only files that git-annex believes have the specified number of
to move content around. You can use this to avoid preferred content copies, on remotes in the specified group. For example,
settings from affecting a subdirectory. For example: `copies=archive:2`
Preferred content expressions have no equivilant to the `--in`
option, but groups can accomplish similar things. You can add
repositories to groups, and match against the groups in a
preferred content expression. So rather than `--in=usbdrive`,
put all the USB drives into a "transfer" group, and use
`copies=transfer:1`
* `lackingcopies=number`
Matches only files that git-annex believes need the specified number or
more additional copies to be made in order to satisfy their numcopies
settings.
* `approxlackingcopies=number`
Like lackingcopies, but does not look at .gitattributes annex.numcopies
settings. This makes it significantly faster.
* `inbackend=name`
Matches only files whose content is stored using the specified key-value
backend.
* `inallgroup=groupname`
Matches only files that git-annex believes are present in all repositories
in the specified group.
* `smallerthan=size` and `largerthan=size`
Matches only files whose content is smaller than, or larger than the
specified size.
The size can be specified with any commonly used units, for example,
"0.5 gb" or "100 KiloBytes"
* `metadata=field=glob`
Matches only files that have a metadata field attached with a value that
matches the glob. The values of metadata fields are matched case
insensitively.
To match a tag "done", use `metadata=tag=done`
To match author metadata, use `metadata=author=* Smith"
* `present`
Makes content be wanted if it's present, but not otherwise.
This leaves it up to you to use git-annex manually
to move content around. You can use this to avoid preferred content
settings from affecting a subdirectory. For example:
auto/* or (include=ad-hoc/* and present) auto/* or (include=ad-hoc/* and present)
Note that `not present` is a very bad thing to put in a preferred content Note that `not present` is a very bad thing to put in a preferred content
expression. It'll make it want to get content that's not present, and expression. It'll make it want to get content that's not present, and
drop content that is present! Don't go there.. drop content that is present! Don't go there..
### difference: "inpreferreddir" * `inpreferreddir`
There's a special "inpreferreddir" keyword you can use in a Makes content be preferred if it's in a directory (located anywhere
preferred content expression of a special remote. This means that the in the tree) with a particular name.
content is preferred if it's in a directory (located anywhere in the tree)
with a special name.
The name of the directory can be configured using The name of the directory can be configured using
`git annex enableremote $remote preferreddir=$dirname` `git annex enableremote $remote preferreddir=$dirname`
(If no directory name is configured, it uses "public" by default.) (If no directory name is configured, it uses "public" by default.)
### difference: "standard" * `standard`
git-annex comes with some built-in preferred content expressions, that git-annex comes with some built-in preferred content expressions, that
can be used with repositories that are in some [[standard_groups]]. can be used with repositories that are in some [[standard_groups]].
When a repository is in exactly one such group, you can use the "standard" When a repository is in exactly one such group, you can use the "standard"
keyword in its preferred content expression, to match whatever content keyword in its preferred content expression, to match whatever content
the group's expression matches. the group's expression matches.
(If a repository is put into multiple standard (If a repository is put into multiple standard
groups, "standard" will match anything.. so don't do that!) groups, "standard" will match anything.. so don't do that!)
Most often, the whole preferred content expression is simply "standard". Most often, the whole preferred content expression is simply "standard".
But, you can do more complicated things, for example: But, you can do more complicated things, for example:
"`standard or include=otherdir/*`" `standard or include=otherdir/*`
### difference: "groupwanted" * `groupwanted`
The "groupwanted" keyword can be used to refer to a preferred content The "groupwanted" keyword can be used to refer to a preferred content
expression that is associated with a group. This is like the "standard" expression that is associated with a group. This is like the "standard"
keyword, but you can configure the preferred content expressions keyword, but you can configure the preferred content expressions
using `git annex groupwanted`. using `git annex groupwanted`.
Note that when writing a groupwanted preferred content expression, Note that when writing a groupwanted preferred content expression,
you can use all of the keywords listed above, including "standard". you can use all of the keywords listed above, including "standard".
(But not "groupwanted".) (But not "groupwanted".)
For example, to make a variant of the standard client preferred content For example, to make a variant of the standard client preferred content
expression that does not want files in the "out" directory, you expression that does not want files in the "out" directory, you
could run: `git annex groupwanted client "standard and exclude=out/*"` could run: `git annex groupwanted client "standard and exclude=out/*"`
Then repositories that are in the client group and have their preferred Then repositories that are in the client group and have their preferred
content expression set to "groupwanted" will use that, while content expression set to "groupwanted" will use that, while
other client repositories that have their preferred content expression other client repositories that have their preferred content expression
set to "standard" will use the standard expression. set to "standard" will use the standard expression.
Or, you could make a new group, with your own custom preferred content Or, you could make a new group, with your own custom preferred content
expression tuned for your needs, and every repository you put in this expression tuned for your needs, and every repository you put in this
group and make its preferred content be "groupwanted" will use it. group and make its preferred content be "groupwanted" will use it.
For example, the archive group only wants to archive 1 copy of each file,
spread among every repository in the group.
Here's how to configure a group named redundantarchive, that instead
wants to contain 3 copies of each file:
For example, the archive group only wants to archive 1 copy of each file,
spread among every repository in the group.
Here's how to configure a group named redundantarchive, that instead
wants to contain 3 copies of each file:
git annex groupwanted redundantarchive "not (copies=redundantarchive:3)" git annex groupwanted redundantarchive "not (copies=redundantarchive:3)"
for repo in foo bar baz; do for repo in foo bar baz; do
git annex group $repo redundantarchive git annex group $repo redundantarchive
git annex wanted $repo groupwanted git annex wanted $repo groupwanted
done done
### difference: metadata matching * `unused`
This: Matches only keys that `git annex unused` has determined to be unused.
git annex get --metadata tag=done This is related the the --unused option.
However, putting `unused` in a preferred content expression
doesn't make git-annex consider those unused keys. So when git-annex is
only checking preferred content expressions against files in the
repository (which are obviously used), `unused` in a preferred
content expression won't match anything.
becomes So when is `unused` useful in a preferred content expression?
metadata=tag=done 1. Using `git annex sync --content --all` will operate on all files,
including unused ones, and take `unused` in preferred content expressions
into account.
2. The git-annex assistant periodically scans for unused files, and
moves them to some repository whose preferred content expression
matches "unused". (Or, if annex.expireunused is set, it may just delete
them.)
### difference: unused * `anything`
The --unused option makes git-annex operate on every key that `git annex Matches any version of any file.
unused` has determined to be unused. The corresponding `unused` keyword
in a preferred content expression also matches those keys.
However, using `unused` in a preferred content expression * `not expression`
doesn't make git-annex consider those keys. So when git-annex is
only checking preferred content expressions against files in the
repository (which are obviously used), `unused` in a preferred
content expression won't match anything.
So when is `unused` useful in a preferred content expression? Inverts what the expression matches. For example, `not include=archive/*`
is the same as `exclude=archive/*`
* The git-annex assistant periodically scans for unused files, and * `and` / `or` / `( expression )`
moves them to some repository whose preferred content expression
matches "unused". (Or, if annex.expireunused is set, it may just delete
them.)
* Using `git annex sync --content --all` will operate on all files,
including unused ones, and take `unused` in preferred content expressions
into account.
### difference: anything These can be used to build up more complicated expressions.
The "anything" keyword can be used in a preferred content expression
to match any version of any file.
## upgrades ## upgrades