Added in 1.9.0

/alias [filename] <aliasname> <command>

Add/remove/replace any single line alias.

This will replace the first matching alias with the new command.

/alias /hello /me says hello

To remove an existing alias:

/alias /hello

If you want to add/remove/replace a alias in an existing file, use:

/alias hello.txt /alias /me says hello

If no filename is specified it will use the first match or the first loaded alias file.