Question

In bash, one can use

env
printev

to print environment(global) variables, or use

set

to print local variables.
However, how could one know, if this variable is from bash scripting environment, or, from the unix operation system?

similar questions to the commands, how could one know

ls
grep
od

etc, is from the Ubuntu OS or from the bash environment?

Answer 1

You can use the type builtin.

[cnicutar@fresh ~]$ type ps
ps is /bin/ps
[cnicutar@fresh ~]$ type type
type is a shell builtin
[cnicutar@fresh ~]$ type ls
ls is aliased to `ls --color=auto'
[cnicutar@fresh ~]$ type if
if is a shell keyword