I ended up writing a script (I'm trying to teach myself the finer points of bash scripting, so that's why you don't see something like Perl here). It's not exactly a simple affair, but it does most of what I need. It uses Kyle's suggestion for looking up individual users' crontabs, but also deals with /etc/crontab (including the scripts launched by run-parts in /etc/cron.hourly, /etc/cron.daily, etc.) and the jobs in the /etc/cron.d directory. It takes all of those and merges them into a display something like the following:
mi h d m w user command
09,39 * * * * root [ -d /var/lib/php5 ] && find /var/lib/php5/ -type f -cmin +$(/usr/lib/php5/maxlifetime) -print0 | xargs -r -0 rm
47 */8 * * * root rsync -axE --delete --ignore-errors / /mirror/ >/dev/null
17 1 * * * root /etc/cron.daily/apt
17 1 * * * root /etc/cron.daily/aptitude
17 1 * * * root /etc/cron.daily/find
17 1 * * * root /etc/cron.daily/logrotate
17 1 * * * root /etc/cron.daily/man-db
17 1 * * * root /etc/cron.daily/ntp
17 1 * * * root /etc/cron.daily/standard
17 1 * * * root /etc/cron.daily/sysklogd
27 2 * * 7 root /etc/cron.weekly/man-db
27 2 * * 7 root /etc/cron.weekly/sysklogd
13 3 * * * archiver /usr/local/bin/offsite-backup 2>&1
32 3 1 * * root /etc/cron.monthly/standard
36 4 * * * yukon /home/yukon/bin/do-daily-stuff
5 5 * * * archiver /usr/local/bin/update-logs >/dev/null
Note that it shows the user, and more-or-less sorts by hour and minute so that I can see the daily schedule.
So far, I've tested it on Ubuntu, Debian, and Red Hat AS.
#!/bin/bash
# System-wide crontab file and cron job directory. Change these for your system.
CRONTAB='/etc/crontab'
CRONDIR='/etc/cron.d'
# Single tab character. Annoyingly necessary.
tab=$(echo -en "\t")
# Given a stream of crontab lines, exclude non-cron job lines, replace
# whitespace characters with a single space, and remove any spaces from the
# beginning of each line.
function clean_cron_lines() {
while read line ; do
echo "${line}" |
egrep --invert-match '^($|\s*#|\s*[[:alnum:]_]+=)' |
sed --regexp-extended "s/\s+/ /g" |
sed --regexp-extended "s/^ //"
done;
}
# Given a stream of cleaned crontab lines, echo any that don't include the
# run-parts command, and for those that do, show each job file in the run-parts
# directory as if it were scheduled explicitly.
function lookup_run_parts() {
while read line ; do
match=$(echo "${line}" | egrep -o 'run-parts (-{1,2}\S+ )*\S+')
if [[ -z "${match}" ]] ; then
echo "${line}"
else
cron_fields=$(echo "${line}" | cut -f1-6 -d' ')
cron_job_dir=$(echo "${match}" | awk '{print $NF}')
if [[ -d "${cron_job_dir}" ]] ; then
for cron_job_file in "${cron_job_dir}"/* ; do # */ <not a comment>
[[ -f "${cron_job_file}" ]] && echo "${cron_fields} ${cron_job_file}"
done
fi
fi
done;
}
# Temporary file for crontab lines.
temp=$(mktemp) || exit 1
# Add all of the jobs from the system-wide crontab file.
cat "${CRONTAB}" | clean_cron_lines | lookup_run_parts >"${temp}"
# Add all of the jobs from the system-wide cron directory.
cat "${CRONDIR}"/* | clean_cron_lines >>"${temp}" # */ <not a comment>
# Add each user's crontab (if it exists). Insert the user's name between the
# five time fields and the command.
while read user ; do
crontab -l -u "${user}" 2>/dev/null |
clean_cron_lines |
sed --regexp-extended "s/^((\S+ +){5})(.+)$/\1${user} \3/" >>"${temp}"
done < <(cut --fields=1 --delimiter=: /etc/passwd)
# Output the collected crontab lines. Replace the single spaces between the
# fields with tab characters, sort the lines by hour and minute, insert the
# header line, and format the results as a table.
cat "${temp}" |
sed --regexp-extended "s/^(\S+) +(\S+) +(\S+) +(\S+) +(\S+) +(\S+) +(.*)$/\1\t\2\t\3\t\4\t\5\t\6\t\7/" |
sort --numeric-sort --field-separator="${tab}" --key=2,1 |
sed "1i\mi\th\td\tm\tw\tuser\tcommand" |
column -s"${tab}" -t
rm --force "${temp}"
