Exit Codes — What 137 Means

~12 min · debug, lifecycle

Level 0Container Curious

0 XP0/36 lessons0/10 achievements

0/120 XP to next level120 XP to go0% complete

The codes you'll actually meet

Code	Meaning	Likely cause
0	Clean exit	Process finished — but maybe it shouldn't have. Long-running services should never exit 0 on their own.
1	Application error	Your code threw, your config is bad, your DB is unreachable. Read logs.
125	Docker daemon error	Bad flag, can't bind port, missing image.
126	Permission denied	CMD isn't executable, or USER lacks permission.
127	Command not found	CMD path is wrong; binary isn't in PATH inside the image.
137	SIGKILL (128+9)	OOM-killer killed it. Hit your --memory limit.
139	SIGSEGV (128+11)	Native crash. Often musl/glibc mismatch on alpine.
143	SIGTERM (128+15)	You stopped it normally — or k8s did during a rollout.

Code

Spot OOM the moment it happens·bash

# Run with too-tight memory
docker run --name greedy --memory=50m python:3.12-slim \
  python -c 'a = bytearray(100*1024*1024)'

# Inspect
docker inspect greedy --format 'state={{.State.Status}} exit={{.State.ExitCode}} oom_killed={{.State.OOMKilled}}'
# state=exited exit=137 oom_killed=true

External links

Docker — exit codes (community guide)

Exercise

Cause each of these exit codes deliberately and capture them: 0, 1, 126 (chmod -x your CMD), 127 (CMD path wrong), 137 (--memory too low). Document each cause and the diagnostic command that surfaced it.

Progress

Progress is local-only — sign in to sync across devices.

← PreviousThe 'Why Won't It Start?' Checklist Next →Network Debugging — netshoot, dig, curl, nslookup

Spotted a bug or have feedback on this page?Report an Issue

Comments 0

🔔 Reply notifications (sign in)

No comments yet — be the first.