slack_last_update.sh: new script, checks Slackware Changelog

1 files changed, 83 insertions, 0 deletions

diff --git a/slack_last_update.sh b/slack_last_update.sh
new file mode 100755
index 0000000..696bed5
--- /dev/null
+++ b/slack_last_update.sh
@@ -0,0 +1,83 @@
+#!/bin/sh
+
+# Get last update time from Slackware ChangeLog, print the date to
+# stdout in the form used by the ##slackware /topic. For now anyway,
+# we assume everything in the ChangeLog is a security fix.
+
+# Also, the output is compared to $DATEFILE if it exists. Exit
+# status is:
+
+# 0 if the date retrieved is the same as in the file,
+# 1 if the date changed (or the file didn't exist),
+# 2 if there was an error of some kind.
+
+# The file is always updated if status is 0 or 1. On status 2,
+# it depends on what the error actually was.
+
+# This script can be tested from the command line, but in production it
+# will be executed from an irssi script, which will use the exit status
+# to decide whether the channel /topic should be updated.
+
+# For the morbidly curious: I intend this to be executed by bash,
+# but it also works with Slackware 14.2's ash and ksh, and dash from
+# SBo. But *not* zsh: somehow $RANGE gets expanded to a quoted string,
+# so curl gets executed as:
+#   curl --silent '--range 0-28' http://...
+# and quite properly complains:
+#   curl: option --range 0-28: is unknown
+# I'm not a zsh guy, if you are & have a fix, let me know.
+
+### Config stuff.
+
+# Where the date get stored
+DATEFILE="$HOME/.slack_last_update"
+
+# Use the primary site, not a mirror.
+URL="http://ftp.slackware.com/pub/slackware/slackware64-14.2/ChangeLog.txt"
+
+# We only really care about the first line of the file. So long as Pat
+# follows his usual practice, the first line (including the newline)
+# is 29 characters long (also 29 bytes, since he uses ASCII). So that's
+# all we'll download from the server. We *could* just do a HEAD request
+# and take the last-modified header, but let's be consistent with the
+# actual content.
+RANGE="--range 0-28"
+
+# Other curl options.
+CURLOPTS="--silent --max-time 60"
+
+# For paranoia's sake:
+PATH=/bin:/usr/bin
+export PATH
+
+# OK, go! (I bet you didn't know 'date' can read from stdin, I didn't)
+DATE="$( curl $CURLOPTS $RANGE "$URL" | date -u -f- '+%F' )"
+
+# Sanity check the date, in case the download failed or Pat got bribed
+# to break this script (I wouldn't blame him, money's money).
+case "$DATE" in
+	[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]) : # OK
+	   ;;
+	*) echo "$0: got '$DATE' instead of a date, bailing" 1>&2
+	   exit 2
+	   ;;
+esac
+
+# Prepare to compare...
+echo "$DATE" > "$DATEFILE.old" || exit 2
+[ -e "$DATEFILE" ] || touch "$DATEFILE"
+[ -e "$DATEFILE" ] || exit 2
+
+# Compare. cmp's exit status is exactly what we want to return, save it.
+cmp -s "$DATEFILE" "$DATEFILE.old"
+RESULT="$?"
+
+# Thought about doing this only if cmp says it's different. Always updating
+# means the timestamp of the file shows us when the last check was, worth
+# the tiny bit of extra I/O.
+mv "$DATEFILE.old" "$DATEFILE" || exit 2
+
+echo "$DATE"
+
+# That's all, folx!
+exit "$RESULT"