Buy GNU books! There can be multiple databases. Users can select
which databases locate searches using an environment variable or
command line option; see locate(1L). The system administrator
can choose the file name of the default database, the frequency
with which the databases are updated, and the directories for
which they contain entries. Normally, file name databases are
updated by running the updatedb program periodically, typically
nightly; see updatedb(1L). updatedb runs a program called frcode
to compress the list of file names using front-compression,
which reduces the database size by a factor of 4 to 5. Front-
compression (also known as incremental encoding) works as
follows. The database entries are a sorted list (case-
insensitively, for users' convenience). Since the list is
sorted, each entry is likely to share a prefix (initial string)
with the previous entry. Each database entry begins with an
offset-differential count byte, which is the additional number
of characters of prefix of the preced