#!/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  # */ 
                    [[ -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}"  # */ 

# 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 <

1.  #!/bin/bash 
2.   
3.  # System-wide crontab file and cron job directory. Change these for your system. 
4.  CRONTAB='/etc/crontab' 
5.  CRONDIR='/etc/cron.d' 
6.   
7.  # Single tab character. Annoyingly necessary. 
8.  tab=$(echo -en "\t") 
9.   
10.  # Given a stream of crontab lines, exclude non-cron job lines, replace 
11.  # whitespace characters with a single space, and remove any spaces from the 
12.  # beginning of each line. 
13.  function clean_cron_lines() { 
14.      while read line ; do 
15.          echo "${line}" | 
16.              egrep --invert-match '^($|\s*#|\s*[[:alnum:]_]+=)' | 
17.              sed --regexp-extended "s/\s+/ /g" | 
18.              sed --regexp-extended "s/^ //" 
19.      done; 
20.  } 
21.   
22.  # Given a stream of cleaned crontab lines, echo any that don't include the 
23.  # run-parts command, and for those that do, show each job file in the run-parts 
24.  # directory as if it were scheduled explicitly. 
25.  function lookup_run_parts() { 
26.      while read line ; do 
27.          match=$(echo "${line}" | egrep -o 'run-parts (-{1,2}\S+ )*\S+') 
28.   
29.          if [[ -z "${match}" ]] ; then 
30.              echo "${line}" 
31.          else 
32.              cron_fields=$(echo "${line}" | cut -f1-6 -d' ') 
33.              cron_job_dir=$(echo  "${match}" | awk '{print $NF}') 
34.   
35.              if [[ -d "${cron_job_dir}" ]] ; then 
36.                  for cron_job_file in "${cron_job_dir}"/* ; do  # */ 
37.                      [[ -f "${cron_job_file}" ]] && echo "${cron_fields} ${cron_job_file}" 
38.                  done 
39.              fi 
40.          fi 
41.      done; 
42.  } 
43.   
44.  # Temporary file for crontab lines. 
45.  temp=$(mktemp) || exit 1 
46.   
47.  # Add all of the jobs from the system-wide crontab file. 
48.  cat "${CRONTAB}" | clean_cron_lines | lookup_run_parts >"${temp}" 
49.   
50.  # Add all of the jobs from the system-wide cron directory. 
51.  cat "${CRONDIR}"/* | clean_cron_lines >>"${temp}"  # */ 
52.   
53.  # Add each user's crontab (if it exists). Insert the user's name between the 
54.  # five time fields and the command. 
55.  while read user ; do 
56.      crontab -l -u "${user}" 2>/dev/null | 
57.          clean_cron_lines | 
58.          sed --regexp-extended "s/^((\S+ +){5})(.+)$/\1${user} \3/" >>"${temp}" 
59.  done <