Cron Job Returns Success But Fails: Detect False Success

Your cron job exits with code 0 (success), but it didn't actually complete its work. Learn how to detect false success.

The Problem: False Success

Scripts can exit with success code (0) even when they fail:

Script catches all exceptions but doesn't verify results
Command succeeds but produces empty or wrong output
Network request returns 200 but contains error message
File operations succeed but files are empty or corrupted
Database query runs but returns no results when data expected
Script completes but doesn't perform intended work

Exit code alone doesn't verify that work was actually completed. You need to validate results.

Solution: Validate Results, Not Just Exit Codes

After running commands, verify that expected results exist. Check file sizes, validate output content, confirm data was written, or verify API responses. The validation must be inside your script, not in the cron line.

Bash Example: Verify Backup File Created

#!/bin/bash
BACKUP_FILE="/backups/db-$(date +%Y%m%d).sql"
# Run backup (might exit 0 even if it fails)
pg_dump mydb > "$BACKUP_FILE"
# Get backup file size (0 if file doesn't exist or is empty)
FILE_SIZE=$(stat -f%z "$BACKUP_FILE" 2>/dev/null || stat -c%s "$BACKUP_FILE" 2>/dev/null || echo 0)
# Single ping with file size in payload
# In DeadManPing panel: set validation rule "size" > 0 (or >= 1024 for minimum size)
# Panel will automatically detect if backup file is empty even though exit code was 0
curl -X POST "https://deadmanping.com/api/ping/backup-daily?size=$FILE_SIZE"

Python Example: Validate API Response

import requests
import sys
# API call might return 200 but with error
response = requests.get("https://api.example.com/data")
# Extract response data for payload
has_error = False
data_count = 0
try:
  data = response.json()
  has_error = "error" in data
  data_count = len(data.get("data", []))
except:
  has_error = True
# Single ping with response data in payload
# In DeadManPing panel: set validation rules:
#   - "status_code" == 200
#   - "has_error" == False
#   - "data_count" > 0
# Panel will automatically detect violations and alert
requests.post(f"https://deadmanping.com/api/ping/api-job?status_code={response.status_code}&has_error={has_error}&data_count={data_count}")

Node.js Example: Verify Database Query Results

const { execSync } = require('child_process');
const https = require('https');
// Query might succeed but return no rows
const output = execSync('psql -c "SELECT COUNT(*) FROM users"', { encoding: 'utf8' });
// Parse count from output
const match = output.match(/(\d+)/);
const count = match ? parseInt(match[1]) : 0;
// Single ping with count in payload
// In DeadManPing panel: set validation rules:
//   - "count" > 0 (to detect empty results)
//   - "count" >= 10 (minimum expected count, optional)
// Panel will automatically detect if count violates rules
https.request(`https://deadmanping.com/api/ping/db-check?count=${count}`, { method: 'POST' }).end();

Bash Example: Verify Multiple Conditions

#!/bin/bash
set -e
# Run sync (might exit 0 even if sync fails)
rsync -avz /data/ user@server:/backup/
# Verify sync actually worked by checking remote file
REMOTE_COUNT=$(ssh user@server "find /backup -type f | wc -l")
LOCAL_COUNT=$(find /data -type f | wc -l)
# Calculate count difference
DIFF=$(( LOCAL_COUNT - REMOTE_COUNT ))
DIFF_ABS=${DIFF#-}
# Single ping with sync data in payload
# In DeadManPing panel: set validation rules:
#   - "local_count" > 0
#   - "count_diff" <= 5 (tolerance)
# Panel will automatically detect if counts don't match
curl -X POST "https://deadmanping.com/api/ping/sync-job?local_count=$LOCAL_COUNT&remote_count=$REMOTE_COUNT&count_diff=$DIFF_ABS"

Detecting False Success with Validation

After adding result validation to your scripts, use a dead man switch to monitor whether validation completed successfully. If your script detects false success and exits with error code, the ping never arrives, and you get an alert.

Include validation details in your ping payload (e.g., file sizes, record counts) so you can track result quality over time and detect gradual degradation.

Working Examples

See complete, working code examples in our GitHub repository:

View Examples on GitHub →

Start Detecting False Success

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Learn more about cron job monitoring and troubleshooting:

Cron Job Returns Success But Fails: Detect False Success

The Problem: False Success

Solution: Validate Results, Not Just Exit Codes

Bash Example: Verify Backup File Created

Python Example: Validate API Response

Node.js Example: Verify Database Query Results

Bash Example: Verify Multiple Conditions

Detecting False Success with Validation

Working Examples

Start Detecting False Success

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