Linux command that is comes built in with shell is called built in command and the other command in Linux usually comes in separates program that reside on your Linux system. The whereis command can be use to specify the location or find the location of these Linux command. The whereis command usually display the location of the command binary file, location of command source code and location of command manual pages.
Find location of Linux command example:
Using whereis command to locate command binary file.
[root@fedora ~]# whereis rm
rm: /bin/rm /usr/share/man/man1p/rm.1p.gz /usr/share/man/man1/rm.1.gz
[root@fedora ~]# whereis ls
ls: /bin/ls /usr/share/man/man1p/ls.1p.gz /usr/share/man/man1/ls.1.gz
Using the whereis command on alias command and cd command did not show any binary file... this is because the alias and cd command is the bash built in command.
[root@fedora ~]# whereis alias
alias: /usr/share/man/man1p/alias.1p.gz /usr/share/man/man1/alias.1.gz
[root@fedora ~]# whereis cd
cd: /usr/share/man/mann/cd.n.gz /usr/share/man/man1p/cd.1p.gz /usr/share/man/man1/cd.1.gz