Which command provides information about an entire library in SAS?

The command that provides information about an entire library in SAS is the one that uses PROC CONTENTS with the DATA= option set to libref.ALL. This command generates a comprehensive report that includes details about all datasets within the specified library reference, such as dataset names, types, variables, and their attributes.

Using PROC CONTENTS allows the user to gain insights into the structure and metadata of the datasets, which is essential for understanding the data available for analysis. When ALL is used as a suffix, it signifies that all datasets in the specified library will be included in the report, making it an effective way to explore the content of a library at a glance.

Other commands listed do not serve the same function. For instance, PROC PRINT focuses on displaying data contents, PROC SUMMARY performs statistical summaries, and PROC LIST is not a standard SAS procedure for obtaining library information. These alternative commands either target specific datasets or lack the capability to provide comprehensive metadata about an entire library, which reinforces why PROC CONTENTS is the appropriate choice in this scenario.