Getty and Login relationship in AIX

Question
Explanation of the relationship between the getty and login programs in AIX.

Answer

In AIX the programs for getty and login are really the same binary: they are
hard or symbolic links to a program called "Terminal State Manager", or tsm.

The fileset that contains the tsm binary and creates some of these links
is bos.rte.security.

The tsm binary checks to see what name it was called by (arg 0) and behaves differently depending on this.

 $ ls -li /etc/getty /usr/sbin/getty /usr/bin/login /bin/login \
 /usr/sbin/login /usr/sbin/tsm

  4406 lrwxrwxrwx   1 root     security      13 Sep 06 09:09 /bin/login -> /usr/sbin/tsm
  1096 lrwxrwxrwx   1 root     security      13 Oct 04 10:35 /etc/getty -> /usr/sbin/tsm
  4406 lrwxrwxrwx   1 root     security      13 Sep 06 09:09 /usr/bin/login -> /usr/sbin/tsm
   204 -r-sr-xr-x   3 root     security   59422 May 18 15:09 /usr/sbin/getty
   204 -r-sr-xr-x   3 root     security   59422 May 18 15:09 /usr/sbin/login
   204 -r-sr-xr-x   3 root     security   59422 May 18 15:09 /usr/sbin/tsm


If the symbolic or hard links are broken, logins may not work correctly.


WHERE IS /ETC/GETTY?

By default most system installs will not include /etc/getty.  This file is
part of the fileset bos.compat.links.  This fileset simply provides symbolic
links.  For example:
 

root# lslpp -l bos.compat.links
bos.compat.links 5.3.0.30 COMMITTED AIX 3.2 to 4 Compatibility

root# lslpp -f bos.compat.links
Fileset File
-----------------------------------------------------------------
Path: /usr/lib/objrepos
bos.compat.links 5.3.0.30

/usr/ucb/fmt -> /usr/bin/fmt
/usr/bin/lsnamsv -> /usr/sbin/lsnamsv
/usr/bin/chroot -> /usr/sbin/chroot
/usr/ucb/fold -> /usr/bin/fold
... excess deleted ....