Debug: Application crashes on startup with no error message

Application crashes immediately on startup with no visible error, exit code, or stack trace.

Systematic debugging when the app dies silently:

# 1. Check exit code
./myapp; echo "Exit code: $?"
# 0 = normal exit (maybe main() returns too early)
# 1 = error
# 137 = killed (OOM)
# 139 = segfault
# 134 = abort

# 2. Check stderr (might be redirected)
./myapp 2>&1 | cat
# Or: ./myapp 2>error.log

# 3. Trace system calls
strace ./myapp 2>&1 | tail -50         # Linux
dtruss ./myapp 2>&1 | tail -50         # macOS
# Look for: failed open(), connect(), mmap()

# 4. Check for missing shared libraries
ldd ./myapp            # Linux
otool -L ./myapp       # macOS
# If 'not found' -> install the library

# 5. Check available memory and resources
ulimit -a
# Look for: max memory, open files, stack size limits

# 6. Environment issues
env | sort > env_dump.txt
# Compare with a working environment
# Common: missing PATH, wrong HOME, missing config dir

# 7. Config file issues
# App might exit if config is invalid
# Check: permissions, syntax, encoding (UTF-8 BOM?)
file config.yml
head -c 3 config.yml | xxd  # Check for BOM bytes

# 8. Port already in use
lsof -i :8080
# If occupied, app exits silently

# 9. Permission issues
namei -l /path/to/executable
# Shows permission chain for entire path

# 10. Add early logging
# If you can modify the code, add a print/log as the
# FIRST line of main() to confirm execution starts

Silent crashes usually mean the error happens before logging is initialized, in a signal handler, or the output goes somewhere unexpected. System-level tools (strace) catch what application logging misses.

Debugging application startup failures