Where are default aliases defined in Amazon Linux?

Question

Playing with VM's (Amazon Linux) and I figured I wanted to add an alias la = "ls -al"

Sure, all good. But in the process, I noticed there were no aliases defined in my home directory (e.g. .bashrc, et. al.) nor in /etc/bashrc.

And yet, when I run alias, I get a bunch of pre-existing aliases...

Where do they come from?

Answer 1

grep alias /etc/*/*

says /etc/profile.d contains shell scripts with alias definitions.

Answer 2

Run PS4=':${BASH_SOURCE}:${LINENO}+' bash -x -l -i to log to stderr every command invoked during your shell's startup with the file name and line number where it came from. Searching this log should make the relevant location clear.