How does one prepare the Oracle environment?

Oracle ships with two utilities to help users prepare the Oracle environment: oraenv and coraenv. One must run "oraenv" or "coraenv" as part of the current environment to set the necessary variables like ORACLE_HOME and ORACLE_SID. To switch from one database or instance to another, just re-execute either oraenv or coraenv.

The coraenv utility is appropriate for the UNIX C Shell:

$ source /usr/local/bin/coraenv
ORACLE_SID= [default]? orcl

oraenv should be used with the other shells like the Bourne, Korn, or Bash shells:

$ . /usr/local/bin/oraenv
ORACLE_SID= [default]? orcl

Never set the Oracle Home directory explicitly in a script. The following examples shows how to use oraenv and coraenv non-interactively from a script:

C-Shell example:

setenv PATH ${PATH}:/usr/local/bin
setenv ORACLE_SID orcl
setenv ORAENV_ASK NO
source /usr/local/bin/coraenv

Here is a SH, KSH or BASH example:

export PATH=${PATH}:/usr/local/bin
export ORACLE_SID=orcl
export ORAENV_ASK=NO
. oraenv

NOTE: the ". " in front of "oraenv" is required to run the script as part of the current shell.