Bliss is a computer virus, introduced in 1997, which aims to infect Linux systems.
In the case of the alpha version, this prevents the executables from running, so users notice it immediately.
The Bliss virus never became widespread, and remains chiefly a research curiosity.
[1] When the Bliss virus was released, antivirus software vendors and Linux distributions released security advisories to notify users of the potential risks.
However, due to the requirement for infection to occur under the root user, the risk is listed as minimal.