The utilities available with the operating system or available from third parties are often very useful in providing additional information that can complete the diagnostic picture or indeed identify specific problems directly, for example, with the environment setup or network.
Tools such as strace and truss might be provided as optional installation components, or are otherwise available for download and installation.
The following external utilities have proved useful in providing supporting information when a problem occurs, or in investigating problems that would be exposed directly to the operating system: