git-fsmonitor—​daemon - A Built-in Filesystem Monitor

A daemon to watch the working directory for file and directory changes using platform-specific filesystem notification facilities.

This daemon communicates directly with commands like git status using the simple IPC interface instead of the slower githooks[5] interface.

This daemon is built into Git so that no third-party tools are required.

This daemon is a long running process used to watch a single working directory and maintain a list of the recently changed files and directories. Performance of commands such as git status can be increased if they just ask for a summary of changes to the working directory and can avoid scanning the disk.

When core.fsmonitor is set to true (see git-config[1]) commands, such as git status, will ask the daemon for changes and automatically start it (if necessary).

For more information see the "File System Monitor" section in git-update-index[1].

The fsmonitor daemon does not currently know about submodules and does not know to filter out filesystem events that happen within a submodule. If fsmonitor daemon is watching a super repo and a file is modified within the working directory of a submodule, it will report the change (as happening against the super repo). However, the client will properly ignore these extra events, so performance may be affected but it will not cause an incorrect result.

By default, the fsmonitor daemon refuses to work with network-mounted repositories; this may be overridden by setting fsmonitor.allowRemote to true. Note, however, that the fsmonitor daemon is not guaranteed to work correctly with all network-mounted repositories, so such use is considered experimental.

On Mac OS, the inter-process communication (IPC) between various Git commands and the fsmonitor daemon is done via a Unix domain socket (UDS) — a special type of file — which is supported by native Mac OS filesystems, but not on network-mounted filesystems, NTFS, or FAT32. Other filesystems may or may not have the needed support; the fsmonitor daemon is not guaranteed to work with these filesystems and such use is considered experimental.

By default, the socket is created in the .git directory. However, if the .git directory is on a network-mounted filesystem, it will instead be created at $HOME/.git-fsmonitor-* unless $HOME itself is on a network-mounted filesystem, in which case you must set the configuration variable fsmonitor.socketDir to the path of a directory on a Mac OS native filesystem in which to create the socket file.

If none of the above directories (.git, $HOME, or fsmonitor.socketDir) is on a native Mac OS file filesystem the fsmonitor daemon will report an error that will cause the daemon and the currently running command to exit.

Everything below this line in this section is selectively included from the git-config[1] documentation. The content is the same as what’s found there:

Part of the git[1] suite