Thursday, August 12, 2010

CheckLog: A Utility for Reviewing the SAS Log

At my previous job, I worked on a SAS program that was intended to be run by someone who did not know SAS. So I needed a utility to tell the user whether the program completed successfully. The final result was a macro called CheckLog that checks a specified log, directory of logs, or the current log for error, warning, invalid, and other messages related to issues in a SAS program.

In order to accomplish this, I first needed a way to export the SAS log to a file so I could read it back in as a SAS data set and search for the terms and phrases associated with issues in the SAS program. Fortunately, there was already a utility available at work that exported the log to a file. The statement that exports the file is a simple DM statement, for example:

dm log "file 'C:\Directory\File.log' replace;" wpgm;

The next step required reading in the log into a data set. Initially, I used the import procedure (i.e., proc import) to import the text file into SAS. However, I needed to specify a delimiter that would not actually delimit the file. I wanted the file to be one large column. So I looked through the SAS font and found a character not common in English, the cedilla ( ¸ ). This character is also not usually found alone, even in languages that use it (like French). At least, I hope it isn't!

The last part is a continuing effort - identify and search for words and phrases associated with issues. The keywords were easy: error, warning, invalid, and uninitialized. The phrases, however, are elusive and open to interpretation. Sometimes phrases like "the data set has 0 observations" may be intended, and therefore should not be searched for. On the other hand, after completing an import, a data set with 0 observations is probably not intended. This type of issue requires the programmer to identify the problem.

Otherwise, the CheckLog macro can identify many common issues of varying levels of importance. Issues like the statement "numeric values have been converted to character values" or the statement "the query requires remerging summary statistics back with the original data" should be identified and resolved to avoid unintended consequences.

The macro includes several options. First, the macro can review a specified log, a directory of logs, or the current SAS log. As long as the file ends with ".log", it can be reviewed with this macro. Second, To enhance reviewing non-SAS logs, I added an argument to add additional keywords, like the word "caution" or "alert". Users could implement user-specified issues (instead of using put statements with the word ERROR or WARNING).

Third, the output can be renamed, with a default of "Log_issues". (When reviewing multiple logs from a directory, this option does not take effect, and the output is named "Logs_w_issues".) Fourth, an option to change the behavior of the pop-up message: always, never, and only when issues are found. Finally, an option to abort the currently executing SAS program if an issue is discovered. This allows the user to run code in production and end it prematurely if issues arise, so the code does not continue to execute with issues.

Readers interested in the macro can join a user group (see below) hosted by Google Groups to download the macro, view documentation, and receive emails when I updated the code. And please, send feedback! I would like to know if the macro works well and whether it checks for all of the issues users require.

CheckLog Site

CheckLog User Group


This group is a forum for the users of the SAS CheckLog macro to receive updates, ask questions, and post feedback. The CheckLog macro checks the SAS log(s) for issues, including lines with error, warning, invalid, or uninitialized messages. Additionally, other phrases associated with issues are checked, and specific phrases are ignored. The macro can also be used with non-SAS logs, as long as the log uses the same issue keywords.

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