Builtin commands, which were introduced in Chapter 7, do not fork a new process when you execute them. This section discusses the type, read, exec, trap, kill, and getopts builtins. Table 27-6 on page 971 lists many bash builtin commands.
The type builtin provides information about a command:
$ type cat echo who if ltcat is hashed (/bin/cat)echo is a shell builtinwho is /usr/bin/whoif is a shell keywordlt is aliased to 'ls -ltrh | tail'
The preceding output shows the files that would be executed if you gave cat or who as a command. Because cat has already been called from the current shell, it is in the hash table (page 1111) and type reports ...