O comportamento padrão do
yum é perguntar sim / on antes de realmente instalar. Há um "--assumeyes", principalmente porque você bugs você com "sim / não" prompts.
Por exemplo:
# yum install s3cmd
# stuff removed
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package s3cmd.noarch 0:1.0.1-1.el6 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
=========================================================================================================================
Package Arch Version Repository Size
=========================================================================================================================
Installing:
s3cmd noarch 1.0.1-1.el6 epel 94 k
Transaction Summary
=========================================================================================================================
Install 1 Package(s)
Total download size: 94 k
Installed size: 320 k
Is this ok [y/N]: n
Similarmente, apenas para "yum update".