10 Practical Bash Script Examples Every Linux Server Admin Should Know

2. Disk usage alert

Check disk usage and send a warning if any partition exceeds 80%:

#!/bin/bash
set -euo pipefail
THRESHOLD=80
df -h | grep -vE '^Filesystem|tmpfs|cdrom' | awk '{ print $5 " " $1 }' |
while read -r output; do
  usage=$(echo "$output" | awk '{ print $1 }' | sed 's/%//')
  partition=$(echo "$output" | awk '{ print $2 }')
  if [ "$usage" -ge "$THRESHOLD" ]; then
    echo "WARNING: $partition at ${usage}% capacity"
  fi
done

Pipe the warning to mail, a Slack webhook, or a monitoring service.

3. Service health watchdog

Restart a service if it stops responding. Useful for critical processes:

#!/bin/bash
set -euo pipefail
SERVICE="nginx"
if ! systemctl is-active --quiet "$SERVICE"; then
  systemctl restart "$SERVICE"
  echo "$SERVICE was down and has been restarted" | logger
fi

Run every minute from cron to keep core services alive without human intervention.

4. Remove old log files

Keep the last 7 days' worth of application logs and purge the rest:

#!/bin/bash
set -euo pipefail
LOG_DIR="/var/log/myapp"
find "$LOG_DIR" -name "*.log" -type f -mtime +7 -delete
echo "Cleaned logs older than 7 days in $LOG_DIR"

Adjust the +7 to match your retention policy.

5. Website health check

Check if a site returns HTTP 200; log failures for review:

#!/bin/bash
set -euo pipefail
URL="https://example.com"
HTTP_CODE=$(curl -o /dev/null -s -w "%{http_code}" "$URL")
if [ "$HTTP_CODE" -ne 200 ]; then
  echo "$URL returned HTTP $HTTP_CODE at $(date)" >> /var/log/healthcheck.log
fi

Extend it to hit multiple sites: loop over a list of URLs in a config file.

6. Database dump with rotation

Dump all databases on a server and keep the newest 30 files:

#!/bin/bash
set -euo pipefail
OUTPUT="/var/db-backups"
mkdir -p "$OUTPUT"
mysqldump --all-databases | gzip > "$OUTPUT/alldb-$(date +%F-%H%M).sql.gz"
find "$OUTPUT" -name "*.sql.gz" -type f -mtime +30 -delete

For PostgreSQL, substitute pg_dumpall.

7. Monitor failed SSH logins

Check recent failed authentication attempts and flag a high threshold:

#!/bin/bash
set -euo pipefail
THRESHOLD=10
FAILED=$(journalctl -u sshd --since "24 hours ago" | grep "Failed password" | wc -l)
if [ "$FAILED" -ge "$THRESHOLD" ]; then
  echo "ALERT: $FAILED failed SSH logins in the last 24 hours"
fi

Combine with a ban script or a notification to check your auth log.

8. Scheduled log rotation

Archive and compress yesterday's access log instead of waiting for logrotate:

#!/bin/bash
set -euo pipefail
LOG="/var/log/nginx/access.log"
ARCHIVE="/var/log/nginx/archive/access-$(date -d yesterday +%F).log.gz"
mv "$LOG" "/tmp/access-rotate"
kill -USR1 $(cat /var/run/nginx.pid)
gzip -c "/tmp/access-rotate" > "$ARCHIVE"
rm "/tmp/access-rotate"

Sending the USR1 signal tells nginx to reopen its log file without dropping connections.

9. Resource snapshot

Log CPU, memory and disk load to a file at intervals — useful for diagnosing intermittent problems:

#!/bin/bash
set -euo pipefail
LOGFILE="/var/log/resource-snapshot.log"
{
  echo "=== $(date) ==="
  echo "LOAD: $(uptime | awk -F'load average:' '{print $2}')"
  echo "MEM: $(free -m | awk '/^Mem:/ {print $3"MB used / "$2"MB total"}')"
  echo "DISK: $(df -h / | awk 'NR==2 {print $5}')"
} >> "$LOGFILE"

10. Simple deployment script

Pull the latest code, install dependencies and restart the application:

#!/bin/bash
set -euo pipefail
DEPLOY_DIR="/var/www/myapp"
cd "$DEPLOY_DIR"
git pull origin main
npm install
npm run build
pm2 restart myapp
echo "Deployed revision $(git rev-parse --short HEAD) at $(date)"

Adapt the build step for your stack — Rails, Laravel, Python — and guard the script with SSH key access only.

Running scripts with cron

To run any script automatically, make it executable (chmod +x script.sh) and add a cron job with crontab -e:

# Every day at 3am
0 3 * * * /usr/local/bin/backup.sh
# Every 5 minutes
*/5 * * * * /usr/local/bin/healthcheck.sh

Always test a new script by hand once before trusting it to cron. A typo that looks harmless in interactive mode can become destructive when repeated automatically.

The bottom line

Bash scripting is the simplest force multiplier available to any server admin. The ten examples here — backups, monitoring health, log rotation, alerts, deployment — cover the tasks that most people either forget to do manually or waste hours repeating. Each can be written, tested and deployed in minutes on your PakiWebHost VPS, and together they turn a hands-on server into something that mostly runs itself.