maddl@NB-Maddl:~$ function a() { echo null; }
maddl@NB-Maddl:~$ a
null
maddl@NB-Maddl:~$ function a_desinfect() { echo desinfect; }
maddl@NB-Maddl:~$ a_desinfect 
desinfect
maddl@NB-Maddl:~$ alias a=a_desinfect
maddl@NB-Maddl:~$ a
desinfect
maddl@NB-Maddl:~$ alias --help
bash: alias: --: Ungültige Option
alias: Gebrauch: alias [-p] [Name[=Wert] ... ]
maddl@NB-Maddl:~$ man alias 
Kein Handbucheintrag für alias vorhanden
maddl@NB-Maddl:~$ alias a=a
maddl@NB-Maddl:~$ a
null
maddl@NB-Maddl:~$