Interview › Scripting (Bash, Groovy)
How do you schedule a script with cron, and what do the five cron fields mean? [Advanced]
Answer
I schedule a script with cron by adding an entry to a user's crontab or /etc/cron.d. The five fields are minute, hour, day of month, month, and day of week, followed by the command.
Technical explanation
Cron has a limited environment, so use absolute paths and set required environment variables explicitly.
Redirect output to logs or monitoring; otherwise cron may mail output depending on system configuration.
Use flock or another lock if overlapping runs would be unsafe.
Hands-on example
# Edit current user's crontab
crontab -e
# Run every 5 minutes
*/5 * * * * /usr/local/bin/health-check.sh >> /var/log/health-check.log 2>&1
# Run daily at 02:30
30 2 * * * /usr/local/bin/backup.sh
Check how well your resume matches the role with our free resume checker— match score, ATS check, and the skills you're missing.
More Scripting (Bash, Groovy) interview questions
- What is the purpose of the shebang line, and what does #!/bin/bash do? [Basic]
- What is the difference between sh and bash? [Basic]
- How do you make a script executable and run it? [Basic]
- What is the difference between running a script with ./script.sh, bash script.sh, and source script.sh? [Basic]
- What does sourcing a script do differently from executing it? [Basic]
- How do you declare a variable in Bash, and why are spaces around = not allowed? [Basic]
- What is the difference between $var and ${var}? [Basic]
- What is the difference between single quotes and double quotes in Bash? [Basic]