Abbreviations are user-defined character sequences or words that are replaced with longer phrases after they are entered. For example, a frequently-run command such as `git checkout` can be abbreviated to `gco`. After entering `gco` and pressing @key{Space} or @key{Enter}, the full text `git checkout` will appear in the command line. The `abbr` command manipulates those abbreviations.
Each abbreviation is stored in its own global or universal variable. The name consists of the prefix `_fish_abbr_` followed by the WORD after being transformed by `string escape style=var`. The WORD cannot contain a space but all other characters are legal.
Defining an abbreviation with global scope is slightly faster than universal scope (which is the default). But in general you'll only want to use the global scope when defining abbreviations in a startup script like `~/.config/fish/config.fish` like this:
You can create abbreviations interactively and they will be visible to other fish sessions if you use the `-U` or `--universal` flag or don't explicitly specify the scope and the abbreviation isn't already defined with global scope. If you want it to be visible only to the current shell use the `-g` or `--global` flag.
- `-a WORD EXPANSION` or `--add WORD EXPANSION` Adds a new abbreviation, causing WORD to be expanded to PHRASE. You can optionally specify `-g` or `--global` to avoid the overhead of universal variables at the expense of not having the definition being immediately visible to other fish shells that are already running. If you don't specify global scope it default to universal. For clarity you can also specify `-U` or `--universal`.
Add a new abbreviation where `gco` will be replaced with `git checkout` global to the current shell. This abbreviation will not be automatically visible to other shells unless the same command is run in those shells (such as when executing the commands in config.fish).