Usage:

mgstat -l mod_gzip_log -d output_dir [-s server_name] [-f b|k|m|g] [-q]

mod_gzip_log - full path to a log file produced by mod_gzip or '-'
if data should be readed from stdin.

output_dir - directory where html, gif and history files are stored.

server_name - server name to print on reports.

f - specify data count format (b - bytes, k - kilobytes, m - megabytes, g - gigabytes).

q - quiet: do not print messages.

Below directives (in httpd.conf) produces desired log file:

LogFormat "%h %l %u %t \"%V %r\" %>s %b mod_gzip: %{mod_gzip_result}n In:%{mod_gzip_input_size}n Out:%{mod_gzip_output_size}n:%{mod_gzip_compression_ratio}npct." common_with_mod_gzip_info2
CustomLog /var/log/httpd/mod_gzip_log common_with_mod_gzip_info2


Usage examples:

mgstat -l /var/log/httpd/mod_gzip.log -d /some/output/dir

cat /var/log/httpd/mod_gzip.log | mstat -l - -d /some/output/dir -q
(read from stdin and be quiet)