Microsoft SQL Server error logs had I/O errors in them. After transferring 4 months’ logs over to a UNIX machine to analyze them with grep/awk/sed, the grep command did not return any output when searching for strings which were present as indicated when viewing the file using the vi editor.
Background & Analysis:
On the UNIX host, I checked the file type of the SQL Server error log as follows:
$> file ERRORLOG.1 ERRORLOG.1: Little-endian UTF-16 Unicode English character data, with very long lines, with CRLF line terminators
So, the grep command couldn’t parse the UTF-16 Unicode file. Hence, the file had to be converted to a format which ‘grep’ could parse. The iconv program helps us perform this file format (character encoding) conversion.
Change the file’s character encoding from UTF-16 to UTF-8 and then perform the grep as follows:
$> iconv -f UTF-16 -t UTF-8 ERRORLOG.1 | grep "SQL Server has encountered.*I/O requests"
The grep program cannot parse files with certain character encodings like UTF-16.
(1) The solution above describes a successful problem-solving experience and may not be applicable to other problems with similar symptoms.
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