先来一个小示例，查看pyqt这个包的编译时间：
genlop -t pyqt
全部参数和使用方法：
#genlop
Usage: genlop [options] [-f logfile] [category/package]
Options:
-c display the currently compiling packages (if any)
-e display package history; default if any option is used.
-f read emerge log information from "logfile" instead of /var/log/emerge.log
-h print this help
-i extra infos for the selected package (build specific USE and CFLAGS
variables, average build time, etc)
-g display GMT/UTC, not localized time.
-l show full merge history.
-n no color in output
-p estimate build time from a piped "emerge -p" output
-q query gentoo.linuxhowtos.org database if no local emerge was found
-r search for portage tree sync/rsync history.
-s use (case insensitive) regular expressions to match package names
-S use case sensitive regular expressions to match package names
-t calculate merge time for the specific package(s).
-u show when packages have been unmerged.
-v display genlop version and exit.
–date datestring1 [ –date datestring2] only shows results between datestring1
and datestring2. datestring2 dafaults to "now" if not explicitly set.
(e.g. genlop –list –date 3 days ago)
This program is licensed under the GPL v2. See COPYING.
For further info about genlop please read the man page.