Progress reporting in Gentoo

I have a bad habit where it comes to updating systems, I tend to do it less frequently than I should, and that can sometimes snowball like it has for my mail server.  Even if it’s a fresh install, sometimes there’s a large number of packages that need installing.

Now Portage does report where it’s up to, but often that has long scrolled past the buffer on your terminal.  You can look at /var/log/emerge.log for this information, but sometimes it’s nice to just see a percentage progress and a pseudo graphical representation.

With this in mind, I cooked up a little script which just tails /var/log/emerge.log and displays a progress bar along with the last message reported. The script is quite short:

#!/bin/bash

shopt -s checkwinsize

stdbuf -o L tail -n 0 -F /var/log/emerge.log | while read line; do
	changed=0
	eval $( echo ${line} | \
		sed -ne '/[0-9]\+ of [0-9]\+/ { s:^.*(\([0-9]\+\) of \([0-9]\+\)).*$:done=\1 total=\2 changed=1:; p; }' )

	if [ "${changed}" = 1 ]; then
		case "${line}" in
			*"::: completed emerge"*)
				;;
			*)
				done=$(( ${done} - 1 ))
				;;
		esac

		percent=$(( ( ${done}*100 ) / ${total} ))
		width=$(( ${COLUMNS:-80} - 8 ))
		progress=$(( ( ${done}*${width} ) / ${total} ))
		remain=$(( ${width} - ${progress} ))

		progressbar="$( for n in $( seq 1 ${progress} ); do echo -n '#'; done )"
		remainbar="$( for n in $( seq 1 ${remain} ); do echo -n ':'; done )"

		printf '\033[2A\033[2K%s\n\033[2K\033[1G[\033[1m%s\033[0m%s] \033[1m%3d%%\033[0m\n' \
			"${line:0:${COLUMNS:-80}}" "$progressbar" "$remainbar" "$percent"
	else
		printf '\033[2A\033[2K%s\n\n' "${line:0:${COLUMNS:-80}}"
	fi

	if echo "${line}" | grep -q '*** terminating.'; then
		exit
	fi
done

What’s it look like?

It works well with GNU Screen as seen above.