When examining /etc/crontab, we see the standard system-wide cron jobs configuration:

# m h dom mon dow user  command
27 *    * * *   root    cd / && run-parts --report /etc/cron.hourly
58 15    * * *   root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )
0 15    * * 7   root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.weekly )
20 15    1 * *   root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.monthly )
#

To force execution of these jobs, you have several options:

Method 1: Directly Run the Commands

# For hourly jobs
sudo cd / && run-parts --report /etc/cron.hourly

# For daily jobs
sudo test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )

Method 2: Using Cron Debug Mode

# Add this line to temporarily debug all cron jobs
* * * * * /usr/bin/logger -t CRON "Testing cron job execution"

Checking System Logs

# Check cron logs on Debian/Ubuntu
grep CRON /var/log/syslog

# On CentOS/RHEL
grep CRON /var/log/cron

Adding Execution Logging

Modify your cron jobs to include logging:

# Original
27 * * * * root cd / && run-parts --report /etc/cron.hourly

# Modified with logging
27 * * * * root (cd / && run-parts --report /etc/cron.hourly) >> /var/log/cron_hourly.log 2>&1

• PATH issues: Cron jobs run with minimal environment variables
• Permission problems: Ensure scripts are executable (chmod +x)
• Time zone mismatches: Check system time vs. cron time

For production systems, consider implementing:

# Sample monitoring script
#!/bin/bash
LOG_FILE="/var/log/cron_monitor.log"
LAST_RUN=$(stat -c %Y /etc/cron.hourly)
CURRENT_TIME=$(date +%s)
DIFF=$((CURRENT_TIME - LAST_RUN))

if [ $DIFF -gt 4000 ]; then
    echo "$(date) - Cron jobs not running!" >> $LOG_FILE
fi

The cron configuration you're showing in /etc/crontab follows the standard Linux format:

# m h dom mon dow user  command
27 *    * * *   root    cd / && run-parts --report /etc/cron.hourly
58 15    * * *   root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )
0 15    * * 7   root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.weekly )
20 15    1 * *   root    test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.monthly )

To check if your cron jobs are running as scheduled:

# Check cron logs (systemd systems)
journalctl -u cron -n 50 --no-pager

# Traditional syslog approach
grep CRON /var/log/syslog | tail -20

# For specific user's jobs
crontab -l -u username

While you can't directly "execute crontab" as a whole, you can manually trigger the scripts:

# For hourly jobs
sudo run-parts --test /etc/cron.hourly
sudo run-parts --verbose /etc/cron.hourly

# For daily jobs (bypassing anacron check)
sudo bash -c "cd / && run-parts --report /etc/cron.daily"

Modify your jobs to include explicit logging:

# Sample modified cron.daily entry
58 15 * * * root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily >> /var/log/cron.daily.log 2>&1 )

Here's a script to verify job execution timestamps:

#!/bin/bash
# cron-verify.sh

LOG_DIR="/var/log/cron"
mkdir -p "$LOG_DIR"

verify_job() {
  local job_name=$1
  local job_path=$2
  local timestamp=$(date +"%Y-%m-%d_%H-%M-%S")
  
  echo "[$timestamp] Verifying $job_name" >> "$LOG_DIR/cron_verify.log"
  
  if [ -d "$job_path" ]; then
    for script in "$job_path"/*; do
      if [ -x "$script" ]; then
        echo "Executing: $script" >> "$LOG_DIR/cron_verify.log"
        "$script" >> "$LOG_DIR/${job_name}_exec.log" 2>&1
      fi
    done
  fi
}

verify_job "hourly" "/etc/cron.hourly"
verify_job "daily" "/etc/cron.daily"
verify_job "weekly" "/etc/cron.weekly"
verify_job "monthly" "/etc/cron.monthly"

Consider these tools for better cron management:

# Install testcron (Debian/Ubuntu)
sudo apt-get install cron-apt

# Sample testcron usage
testcron -f /etc/crontab -u root