When working with cron jobs, you can use specific patterns in the minute field to achieve odd/even execution:

# Odd minutes (1,3,5,...,59)
1-59/2 * * * * /path/to/odd-minute-script.sh

# Even minutes (0,2,4,...,58)
0-58/2 * * * * /path/to/even-minute-script.sh

For better readability and maintenance, consider these alternatives:

# Using comma-separated values (odd minutes)
1,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33,35,37,39,41,43,45,47,49,51,53,55,57,59 * * * * /path/to/odd-job

# Using step values (preferred method)
*/2 * * * * /path/to/even-job  # Runs at :00, :02, ..., :58
1-59/2 * * * * /path/to/odd-job # Runs at :01, :03, ..., :59

To test your cron jobs before deploying:

# Check next execution times
crontab -l | grep -v "^#" | while read -r line; do
  echo "Next run times for: $line"
  for i in {1..5}; do
    echo -n "$i. "
    echo "$line" | awk '{print $1" "$2" "$3" "$4" "$5}' | xargs -I {} date -d "now + {}" "+%Y-%m-%d %H:%M:%S"
  done
done

Here's a complete example for monitoring system resources:

# Even minute job - system monitoring
0-58/2 * * * * /usr/bin/printf "EVEN MINUTE: $(date) - CPU: $(grep 'cpu ' /proc/stat | awk '{usage=($2+$4)*100/($2+$4+$5)} END {print usage "%"}')" >> /var/log/system_mon.log

# Odd minute job - cleanup task
1-59/2 * * * * find /tmp -type f -mmin +60 -delete

• Ensure your system's cron daemon supports the step syntax (most modern systems do)
• Account for potential job overlap if tasks run longer than 1 minute
• Consider using flock for preventing concurrent execution
• Test thoroughly in non-production environments first

When working with cron jobs, sometimes we need more granular control than the standard */2 minute interval. The requirement here is to have:

• Job A: Runs at every odd minute (1,3,5,...,59)
• Job B: Runs at every even minute (0,2,4,...,58)

The most straightforward way to achieve this is by using step values and ranges in your crontab:

# For odd minutes (1-59, stepping by 2)
1-59/2 * * * * /path/to/odd_job.sh

# For even minutes (0-58, stepping by 2)
0-58/2 * * * * /path/to/even_job.sh

If you prefer a different approach, you can also use comma-separated values for even minutes:

# For even minutes
0,2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,32,34,36,38,40,42,44,46,48,50,52,54,56,58 * * * * /path/to/even_job.sh

However, the first method is more maintainable and easier to understand.

After setting up your cron jobs, you can verify them using:

crontab -l

To test the timing pattern without waiting, you can use tools like:

# For testing the odd minute job
for i in {1..59..2}; do echo "Testing minute $i"; /path/to/odd_job.sh; done

This alternating cron pattern is useful for:

• Load balancing between two processes
• Implementing round-robin processing
• Running maintenance tasks in staggered intervals
• A/B testing scheduled jobs