First, if no -S flag was given, and if the file install-directory/lib/dbxrc exists and is readable, dbx reads it. (The path to the site-specific initialization file is derived from the path to the dbx executable.)
dbx searches for the file .dbxrc in the current directory, then in $HOME. If the file is not found, dbx searches for .dbxinit in the current directory, then in $HOME. A different startup file may be given explicitly via the -s command-line option. See The .dbxrc File for a sample .dbxrc file.
A startup file may contain any dbx command. Most commonly, it contains alias and function definitions. It may also source other files using the source or . command (see source Command and . Command). The startup file is also a good place to set various options via set -o and dbxenv.
If you have no startup file, or if you have .dbxrc in the current directory or in $HOME, then the alias command is aliased to kalias. If you have a .dbxinit file in the current directory or in $HOME and no .dbxrc' file, then alias is aliased to dalias. This is done to provide backward compatibility for users of previous versions of dbx. You may use your old .dbxinit file without changes by adding the following three lines to your .dbxrc file:
kalias alias=dalias
source ~/.dbxinit
kalias alias=kalias