Originally Posted by Huamin
It is fine now. Do you think it is due to files accidentally deleted or any other reasons for this problem?
That depends on how the oracle user was set up. It may have been set up manually or during oracle software package installation. If it was set up during oracle package installation it may derive from Oracle themselves or it may have been added by the packagers.
Judging from questions seen at LQ and elsewhere on the Internet about oracle login shell customisation (like this one) and shell integration generally (including shell scripting), Oracle themselves do not provide much. I get the distinct impression that they have done the minimum necessary with the shell to get their specialised software products working. The oracle user's shell configuration seems to be basic rather than convenient, the shell scripts are simple rather than well styled and error trapped. Maybe Oracle favour KISS to avoid the maintenance burden of maintaining a lot of sophisticated software for use in a variety of environments.
The most likely explanation for the experience you have had is that the files were not created when the oracle user was set up.