Answer by Brian for How can I combine two commands to tally data from compressed and uncompressed log files?

Can use zgrep which will decompress if necessary and therefore works with both straight text and compressed input. As well grep/zgrep can process multiple files directly which is needed in this case since mixed compressed and text to standard input doesn't always work as intended. Supress filenames in the grep output with -h or --no-filename.

sudo zgrep -h 'Failed password' /var/log/auth.* | grep sshd | awk '{print $1,$2}' | sort -k 1,1M -k 2n | uniq -c

Man page:

ZGREP(1)                                                              ZGREP(1)NAME       zgrep - search possibly compressed files for a regular expressionSYNOPSIS       zgrep [ grep_options ] [ -e ] pattern filename...DESCRIPTION       Zgrep  invokes grep on compressed or gzipped files.  All options specified       are passed directly to grep.  If no file is specified, then  the  standard       input  is  decompressed if necessary and fed to grep.  Otherwise the given       files are uncompressed if necessary and fed to grep.       If the GREP environment variable is set, zgrep uses it as the grep program       to be invoked.AUTHOR       Charles Levert (charles@comm.polymtl.ca)SEE ALSO       grep(1), gzexe(1), gzip(1), zdiff(1), zforce(1), zmore(1), znew(1)