If monitoring Oracle databases is part of your job, then some supervision programs need Oracle sqlplus command-line to access remote databases and perform some health status checks.
In order to have it on your systems, just download Oracle instant client. It is available on many platforms (Windows 32 and x64, Linux x86 and x86-64, AIX) and free of charge.You can download it as a rpm file or zip one according to your needs. To proceed the download, an Oracle account is required. The subscription is free and very easy to do.
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