157 lines
5.3 KiB
Bash
Executable file
157 lines
5.3 KiB
Bash
Executable file
#!/bin/sh
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#
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# 50-motd-news - print the live news from the Ubuntu wire
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# Copyright (C) 2016-2020 Canonical Ltd.
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# Copyright (C) 2016-2017 Dustin Kirkland
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#
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# Authors: Dustin Kirkland <kirkland@canonical.com>
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# Steve Langasek <steve.langasek@canonical.com>
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License along
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# with this program; if not, write to the Free Software Foundation, Inc.,
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# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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##############################################################################
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# This program could be rewritten in C or Golang for faster performance.
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# Or it could be rewritten in Python or another higher level language
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# for more modularity.
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# However, I've insisted on shell here for transparency!
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# - Dustin
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##############################################################################
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# Source the local configuration
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[ -r /etc/default/motd-news ] && . /etc/default/motd-news
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# Exit immediately, unless we're enabled
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# This makes this script very easy to disable in /etc/default/motd-news configuration
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[ "$ENABLED" = "1" ] || exit 0
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# Ensure sane defaults
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[ -n "$URLS" ] || URLS="https://motd.ubuntu.com"
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[ -n "$WAIT" ] || WAIT=5
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[ -n "$CACHE" ] || CACHE="/var/cache/motd-news"
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[ "$1" = "--force" ] && FORCED=1
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# Ensure we print safely, maximum of the first 10 lines,
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# maximum of the first 80 chars per line, no control chars
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safe_print() {
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cat "$1" | head -n 10 | tr -d '\000-\011\013\014\016-\037' | cut -c -80
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}
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# If we're not forcing an update, and we have a cached motd-news file,
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# then just print it and exit as quickly as possible, for login performance.
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# Note that systemd should keep this cache file up to date, asynchronously
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if [ "$FORCED" != "1" ]; then
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if [ -r $CACHE ]; then
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echo " * News:"
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safe_print $CACHE
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elif [ "$(id -u)" -eq 0 ]; then
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printf " * News:\n * No News\n"
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: > $CACHE
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fi
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exit 0
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fi
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# If we've made it here, we've been given the --force argument,
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# probably from the systemd motd-news.service. Let's update...
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# Abort early if wget is missing
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[ -x /usr/bin/wget ] || exit 0
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# Generate our temp files, clean up when done
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NEWS=$(mktemp) || exit 1
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ERR=$(mktemp) || exit 1
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CLOUD=$(mktemp) || exit 1
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trap "rm -f $NEWS $ERR $CLOUD" HUP INT QUIT ILL TRAP KILL BUS TERM
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# Construct a user agent, similar to Firefox/Chrome/Safari/IE to
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# ensure a proper, tailored, accurate message of the day
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# wget browser version, for debug purposes
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wget_ver="$(dpkg -l wget | awk '$1 == "ii" { print($3); exit(0); }')"
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# Distribution version, for messages releated to this Ubuntu release
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. /etc/lsb-release
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lsb=$(echo "$DISTRIB_DESCRIPTION" | sed -e "s/ /\//g")
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codename="$DISTRIB_CODENAME"
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# Kernel version and CPU type, for messages related to a particular revision or hardware
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platform="$(uname -o)/$(uname -r)/$(uname -m)"
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arch="$(uname -m)"
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cpu="$(grep -m1 "^model name" /proc/cpuinfo | sed -e "s/.*: //" -e "s:\s\+:/:g")"
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cloud_id="unknown"
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if [ -x /usr/bin/cloud-id ]; then
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/usr/bin/cloud-id > "$CLOUD" 2>/dev/null
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if [ "$?" -eq "0" ]; then
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# sanitize it a bit, just in case
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cloud_id=$(cut -c -40 "${CLOUD}" | tr -c -d '[:alnum:]')
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if [ -z "${cloud_id}" ]; then
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cloud_id="unknown"
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fi
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fi
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fi
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# Piece together the user agent
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USER_AGENT="wget/$wget_ver $lsb $platform $cpu cloud_id/$cloud_id"
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# Loop over any configured URLs
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for u in $URLS; do
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# Ensure https:// protocol, for security reasons
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case $u in
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https://*)
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true
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;;
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https://motd.ubuntu.com)
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u="$u/$codename/$arch"
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;;
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call*)
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cmd=$(echo $u|cut -c 6-)
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response=$($cmd)
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title=$(echo "$response"|grep -E " \* " --color=never)
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url=$(echo "$response"|tail -1)
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echo "$title\n\n$url" > "$CACHE"
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continue
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;;
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*)
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continue
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;;
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esac
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# If we're forced, set the wait to much higher (1 minute)
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[ "$FORCED" = "1" ] && WAIT=60
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# Fetch and print the news motd
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result=0
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not_found_is_ok=0
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wget --timeout "$WAIT" -U "$USER_AGENT" -O- --content-on-error "$u" >"$NEWS" 2>"$ERR" || result=$?
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# from wget's manpage: 8 Server issued an error response.
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if [ $result -eq 8 ]; then
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if grep -q "ERROR 404" "$ERR"; then
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# The server's 404 document is the generic, non cloud-specific, motd-news
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# content present in the index.txt file
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not_found_is_ok=1
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fi
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fi
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if [ $result -eq 0 ] || [ $not_found_is_ok -eq 1 ]; then
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echo
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# At most, 10 lines of text, remove control characters, print at most 80 characters per line
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echo " * News:"
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safe_print "$NEWS"
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# Try to update the cache
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safe_print "$NEWS" 2>/dev/null >$CACHE || true
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else
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printf " * News:\n * No News"
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echo " * No News" > "$CACHE"
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fi
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done
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rm -f "$NEWS" "$ERR" "$CLOUD"
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exit 0
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