pattern attr1 attr2 ...
That is, a pattern followed by an attributes list,
-separated by whitespaces. When the pattern matches the
-path in question, the attributes listed on the line are given to
-the path.
+separated by whitespaces. Leading and trailing whitespaces are
+ignored. Lines that begin with '#' are ignored. Patterns
+that begin with a double quote are quoted in C style.
+When the pattern matches the path in question, the attributes
+listed on the line are given to the path.
Each attribute can be in one of these states for a given path:
Attributes for all users on a system should be placed in the
`$(prefix)/etc/gitattributes` file.
-Sometimes you would need to override an setting of an attribute
+Sometimes you would need to override a setting of an attribute
for a path to `Unspecified` state. This can be done by listing
the name of the attribute prefixed with an exclamation point `!`.
This attribute sets a specific line-ending style to be used in the
working directory. It enables end-of-line conversion without any
-content checks, effectively setting the `text` attribute.
+content checks, effectively setting the `text` attribute. Note that
+setting this attribute on paths which are in the index with CRLF line
+endings may make the paths to be considered dirty. Adding the path to
+the index again will normalize the line endings in the index.
Set to string value "crlf"::
-------------------------------------------------
$ echo "* text=auto" >.gitattributes
-$ rm .git/index # Remove the index to force Git to
-$ git reset # re-scan the working directory
+$ git add --renormalize .
$ git status # Show files that will be normalized
-$ git add -u
-$ git add .gitattributes
$ git commit -m "Introduce end-of-line normalization"
-------------------------------------------------
fed the blob object from its standard input, and its standard
output is used to update the worktree file. Similarly, the
`clean` command is used to convert the contents of worktree file
-upon checkin.
+upon checkin. By default these commands process only a single
+blob and terminate. If a long running `process` filter is used
+in place of `clean` and/or `smudge` filters, then Git can process
+all blobs with a single filter command invocation for the entire
+life of a single Git command, for example `git add --all`. If a
+long running `process` filter is configured then it always takes
+precedence over a configured single blob filter. See section
+below for the description of the protocol used to communicate with
+a `process` filter.
One use of the content filtering is to massage the content into a shape
that is more convenient for the platform, filesystem, and the user to use.
into a usable content by setting the filter.<driver>.required configuration
variable to `true`.
+Note: Whenever the clean filter is changed, the repo should be renormalized:
+$ git add --renormalize .
+
For example, in .gitattributes, you would assign the `filter`
attribute for paths.
should not try to access the file on disk, but only act as filters on the
content provided to them on standard input.
+Long Running Filter Process
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+If the filter command (a string value) is defined via
+`filter.<driver>.process` then Git can process all blobs with a
+single filter invocation for the entire life of a single Git
+command. This is achieved by using a packet format (pkt-line,
+see technical/protocol-common.txt) based protocol over standard
+input and standard output as follows. All packets, except for the
+"*CONTENT" packets and the "0000" flush packet, are considered
+text and therefore are terminated by a LF.
+
+Git starts the filter when it encounters the first file
+that needs to be cleaned or smudged. After the filter started
+Git sends a welcome message ("git-filter-client"), a list of supported
+protocol version numbers, and a flush packet. Git expects to read a welcome
+response message ("git-filter-server"), exactly one protocol version number
+from the previously sent list, and a flush packet. All further
+communication will be based on the selected version. The remaining
+protocol description below documents "version=2". Please note that
+"version=42" in the example below does not exist and is only there
+to illustrate how the protocol would look like with more than one
+version.
+
+After the version negotiation Git sends a list of all capabilities that
+it supports and a flush packet. Git expects to read a list of desired
+capabilities, which must be a subset of the supported capabilities list,
+and a flush packet as response:
+------------------------
+packet: git> git-filter-client
+packet: git> version=2
+packet: git> version=42
+packet: git> 0000
+packet: git< git-filter-server
+packet: git< version=2
+packet: git< 0000
+packet: git> capability=clean
+packet: git> capability=smudge
+packet: git> capability=not-yet-invented
+packet: git> 0000
+packet: git< capability=clean
+packet: git< capability=smudge
+packet: git< 0000
+------------------------
+Supported filter capabilities in version 2 are "clean", "smudge",
+and "delay".
+
+Afterwards Git sends a list of "key=value" pairs terminated with
+a flush packet. The list will contain at least the filter command
+(based on the supported capabilities) and the pathname of the file
+to filter relative to the repository root. Right after the flush packet
+Git sends the content split in zero or more pkt-line packets and a
+flush packet to terminate content. Please note, that the filter
+must not send any response before it received the content and the
+final flush packet. Also note that the "value" of a "key=value" pair
+can contain the "=" character whereas the key would never contain
+that character.
+------------------------
+packet: git> command=smudge
+packet: git> pathname=path/testfile.dat
+packet: git> 0000
+packet: git> CONTENT
+packet: git> 0000
+------------------------
+
+The filter is expected to respond with a list of "key=value" pairs
+terminated with a flush packet. If the filter does not experience
+problems then the list must contain a "success" status. Right after
+these packets the filter is expected to send the content in zero
+or more pkt-line packets and a flush packet at the end. Finally, a
+second list of "key=value" pairs terminated with a flush packet
+is expected. The filter can change the status in the second list
+or keep the status as is with an empty list. Please note that the
+empty list must be terminated with a flush packet regardless.
+
+------------------------
+packet: git< status=success
+packet: git< 0000
+packet: git< SMUDGED_CONTENT
+packet: git< 0000
+packet: git< 0000 # empty list, keep "status=success" unchanged!
+------------------------
+
+If the result content is empty then the filter is expected to respond
+with a "success" status and a flush packet to signal the empty content.
+------------------------
+packet: git< status=success
+packet: git< 0000
+packet: git< 0000 # empty content!
+packet: git< 0000 # empty list, keep "status=success" unchanged!
+------------------------
+
+In case the filter cannot or does not want to process the content,
+it is expected to respond with an "error" status.
+------------------------
+packet: git< status=error
+packet: git< 0000
+------------------------
+
+If the filter experiences an error during processing, then it can
+send the status "error" after the content was (partially or
+completely) sent.
+------------------------
+packet: git< status=success
+packet: git< 0000
+packet: git< HALF_WRITTEN_ERRONEOUS_CONTENT
+packet: git< 0000
+packet: git< status=error
+packet: git< 0000
+------------------------
+
+In case the filter cannot or does not want to process the content
+as well as any future content for the lifetime of the Git process,
+then it is expected to respond with an "abort" status at any point
+in the protocol.
+------------------------
+packet: git< status=abort
+packet: git< 0000
+------------------------
+
+Git neither stops nor restarts the filter process in case the
+"error"/"abort" status is set. However, Git sets its exit code
+according to the `filter.<driver>.required` flag, mimicking the
+behavior of the `filter.<driver>.clean` / `filter.<driver>.smudge`
+mechanism.
+
+If the filter dies during the communication or does not adhere to
+the protocol then Git will stop the filter process and restart it
+with the next file that needs to be processed. Depending on the
+`filter.<driver>.required` flag Git will interpret that as error.
+
+After the filter has processed a command it is expected to wait for
+a "key=value" list containing the next command. Git will close
+the command pipe on exit. The filter is expected to detect EOF
+and exit gracefully on its own. Git will wait until the filter
+process has stopped.
+
+Delay
+^^^^^
+
+If the filter supports the "delay" capability, then Git can send the
+flag "can-delay" after the filter command and pathname. This flag
+denotes that the filter can delay filtering the current blob (e.g. to
+compensate network latencies) by responding with no content but with
+the status "delayed" and a flush packet.
+------------------------
+packet: git> command=smudge
+packet: git> pathname=path/testfile.dat
+packet: git> can-delay=1
+packet: git> 0000
+packet: git> CONTENT
+packet: git> 0000
+packet: git< status=delayed
+packet: git< 0000
+------------------------
+
+If the filter supports the "delay" capability then it must support the
+"list_available_blobs" command. If Git sends this command, then the
+filter is expected to return a list of pathnames representing blobs
+that have been delayed earlier and are now available.
+The list must be terminated with a flush packet followed
+by a "success" status that is also terminated with a flush packet. If
+no blobs for the delayed paths are available, yet, then the filter is
+expected to block the response until at least one blob becomes
+available. The filter can tell Git that it has no more delayed blobs
+by sending an empty list. As soon as the filter responds with an empty
+list, Git stops asking. All blobs that Git has not received at this
+point are considered missing and will result in an error.
+
+------------------------
+packet: git> command=list_available_blobs
+packet: git> 0000
+packet: git< pathname=path/testfile.dat
+packet: git< pathname=path/otherfile.dat
+packet: git< 0000
+packet: git< status=success
+packet: git< 0000
+------------------------
+
+After Git received the pathnames, it will request the corresponding
+blobs again. These requests contain a pathname and an empty content
+section. The filter is expected to respond with the smudged content
+in the usual way as explained above.
+------------------------
+packet: git> command=smudge
+packet: git> pathname=path/testfile.dat
+packet: git> 0000
+packet: git> 0000 # empty content!
+packet: git< status=success
+packet: git< 0000
+packet: git< SMUDGED_CONTENT
+packet: git< 0000
+packet: git< 0000 # empty list, keep "status=success" unchanged!
+------------------------
+
+Example
+^^^^^^^
+
+A long running filter demo implementation can be found in
+`contrib/long-running-filter/example.pl` located in the Git
+core repository. If you develop your own long running filter
+process then the `GIT_TRACE_PACKET` environment variables can be
+very helpful for debugging (see linkgit:git[1]).
+
+Please note that you cannot use an existing `filter.<driver>.clean`
+or `filter.<driver>.smudge` command with `filter.<driver>.process`
+because the former two use a different inter process communication
+protocol than the latter one.
+
+
Interaction between checkin/checkout attributes
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^