Tmux

AI

Quick Reference Guide

The Ultimate Exit Code Encyclopedia

Stop guessing what 137 or 203 means. The most comprehensive reference for Linux, BSD, Systemd, and Protocol exit status.

55 Entries Tracked

7 Tool Families

Understanding Signals (128+n)

If an exit code is greater than 128, it often means the process was killed by a fatal signal. To find the signal number, subtract 128 from the exit code.

Code 137 - 128 = 9 (SIGKILL)Code 130 - 128 = 2 (SIGINT)

High Value Codes (>256)

Linux stores exit codes in 2-byte values. Bits 8-15 contain the actual code, while bits 0-6 represent the signal.

Code 32512 = 127 (Not Found)Calc: 32512 % 256

Bash Shell

5 entries

Misuse of Shell Builtins

Shell builtin used incorrectly or bad syntax.

Bash returns 2 for syntax errors or misuse of builtins.

Fix syntax or quoting.
Pass valid arguments to the builtin.

#syntax#bash#shell

Command Invoked Cannot Execute

Command exists but cannot be executed.

Shell found the file but execution failed.

chmod +x the file or use a valid binary.
Use the correct interpreter or rebuild for the platform.

#permission#bash#execution

Command Not Found

Shell cannot locate the command in PATH.

Returned by the shell when lookup fails.

Install the command.
Add its directory to PATH or use the full path.

#not-found#bash#path

Invalid Argument to Exit

Exit invoked with a non-integer status.

Shell expects an integer between 0 and 255.

Ensure exit receives an integer 0-255.

#scripting#bash

Program Interrupted (SIGINT)

Process interrupted by Ctrl+C (SIGINT).

128 + SIGINT (2) = 130.

Avoid sending SIGINT if you need graceful shutdown.
Handle SIGINT to clean up before exit.

#signal#interruption#sigint

Standard / Unix

9 entries

Successful Termination

The command finished successfully.

Standard success for Unix-like processes.

No action required unless the script logic is incorrect.

#success#bash#standard

General Error

Generic failure when no specific exit code applies.

Catch-all error used by many programs.

Correct inputs or environment and retry.
Fix the underlying error reported by the tool.

#error#bash#catch-all

No Such Device or Address

Invalid device, address, or host.

System call reported a bad device/address; some tools surface it as exit 6.

Correct the target address.
Ensure the device or host is reachable.

#network#dns#device

Program Abort (SIGABRT)

Process aborted itself (SIGABRT).

128 + SIGABRT (6) = 134.

Fix the underlying bug or assertion.
Update dependencies that triggered the abort.

#signal#abort#sigabrt

Arithmetic Error (SIGFPE)

Erroneous arithmetic operation (SIGFPE).

128 + SIGFPE (8) = 136.

Guard against invalid math.
Fix overflow/underflow bugs.

#signal#math#sigfpe

Killed (SIGKILL)

Process killed by SIGKILL, often OOM.

128 + SIGKILL (9) = 137.

Increase memory limits or reduce usage.
Find memory leaks and cap resource usage.

#oom#sigkill#crash#kubernetes#docker

Segmentation Fault (SIGSEGV)

Segmentation fault (SIGSEGV).

128 + SIGSEGV (11) = 139.

Fix memory safety bugs.
Update or roll back native dependencies.

#segfault#sigsegv#crash#bug

Terminated (SIGTERM)

Process terminated by SIGTERM.

128 + SIGTERM (15) = 143.

Handle SIGTERM for graceful shutdown.
Increase stop timeout if cleanup needs more time.

#signal#termination#sigterm

Maximum Exit Code

Exit status 255, often used for fatal errors.

Exit status wraps to 255 or indicates fatal failure (e.g., SSH).

Fix the underlying fatal error.
Resolve SSH auth, DNS, or network issues.

#standard#wrap-around

GNU Coreutils

2 entries

Command Timed Out

Command exceeded the time limit enforced by timeout.

Returned by GNU timeout when the child process times out.

Increase timeout or optimize the command.
Add retries or timeouts inside the process.

Command Failure

The timeout wrapper failed before running the command.

GNU timeout encountered an internal error.

Fix the timeout invocation.
Resolve system limits or permission issues.

Systemd Units

17 entries

EXIT_CHDIR

Changing to working directory failed.

Systemd could not enter WorkingDirectory=.

Create the directory or update permissions.

#systemd#config#directory

EXIT_NICE

Setting scheduling priority failed.

Systemd could not apply Nice=.

Use a valid nice level or adjust privileges.

#systemd#config#priority

EXIT_FDS

Failed to manage file descriptors.

Systemd could not close or set file descriptors.

Raise FD limits or fix the service config.

EXIT_EXEC

Process execution failed.

execve() failed for the configured command.

Fix the path/permissions or install the binary.

#systemd#error#execution

EXIT_MEMORY

Memory shortage.

Systemd could not allocate required memory.

Increase memory or reduce service footprint.

#systemd#oom#memory

EXIT_LIMITS

Failed to adjust resource limits.

Systemd could not apply Limit* settings.

Use limits supported by the OS.

#systemd#config#limits

EXIT_OOM_ADJUST

Failed to adjust OOM setting.

Systemd could not apply OOMScoreAdjust=.

Set a value between -1000 and 1000.

#systemd#config#oom

EXIT_STDIN

Failed to set up standard input.

StandardInput= is invalid or inaccessible.

Fix input configuration or permissions.

#systemd#config#io

EXIT_STDOUT

Failed to set up standard output.

StandardOutput= is invalid or inaccessible.

Fix output configuration or permissions.

#systemd#config#io

EXIT_CHROOT

Failed to change root directory.

RootDirectory= or RootImage= is invalid.

Fix RootDirectory= or RootImage= values.

#systemd#config#chroot

EXIT_SETSCHEDULER

Failed to set up CPU scheduling.

Scheduling policy/priority is invalid or unsupported.

Use supported scheduling values.

#systemd#config#cpu

EXIT_GROUP

Failed to change group credentials.

Configured group or supplementary group is invalid.

Create the group or fix Group= settings.

#systemd#config#auth

EXIT_USER

Failed to change user credentials.

Configured user is invalid or missing.

Create the user or fix User= settings.

#systemd#config#auth

EXIT_NETWORK

Failed to set up network namespace.

PrivateNetwork= could not be configured.

Disable PrivateNetwork= or update the kernel.

#systemd#config#network

EXIT_NAMESPACE

Failed to set up namespaces.

Namespace restrictions are invalid or conflicting.

Fix conflicting paths or namespace config.

#systemd#config#namespace

EXIT_NO_NEW_PRIVILEGES

Failed to disable new privileges.

Kernel does not support or rejects no_new_privs.

Upgrade kernel or disable the setting.

#systemd#config#security

EXIT_NUMA_POLICY

Failed to set NUMA policy.

NUMA policy or mask is invalid or unsupported.

Use valid NUMA settings or disable them.

#systemd#config#numa

BSD Sysexits

15 entries

EX_USAGE

Command line usage error.

Wrong flags or argument structure.

Correct the command syntax per documentation.

#bsd#syntax#usage

EX_DATAERR

Input data format error.

Data is malformed or incorrect.

Fix the data source or regenerate valid input.

EX_NOINPUT

Cannot open input.

Input file is missing or unreadable.

Provide the correct file path or permissions.

EX_NOUSER

Addressee unknown.

Specified user or address does not exist.

Use a valid user or create the account.

EX_NOHOST

Host name unknown.

Host cannot be resolved.

Fix the hostname or DNS settings.

#bsd#network#dns

EX_UNAVAILABLE

Service unavailable.

Required service or support program is missing.

Start the service or install the missing dependency.

EX_SOFTWARE

Internal software error.

Application bug or unhandled exception.

Fix the bug or update to a patched version.

#bsd#bug#software

EX_OSERR

System error.

Operating system failure (fork, pipe, etc.).

Free resources or raise system limits.

EX_OSFILE

Critical OS file missing.

Essential system file is missing or unreadable.

Restore the file or reinstall the package.

EX_CANTCREAT

Cannot create output.

Failed to create or write output file.

Free disk space or adjust permissions.

EX_IOERR

Input/output error.

Physical I/O error during file operations.

Repair storage or remount the filesystem.

EX_TEMPFAIL

Temporary failure.

Transient error; retry later.

Add retry/backoff or wait for recovery.

#bsd#temp#retry

EX_PROTOCOL

Remote protocol error.

Remote side sent invalid or unexpected protocol data.

Upgrade/downgrade to compatible versions.

#bsd#protocol#network

EX_NOPERM

Permission denied.

Insufficient privileges to perform the operation.

Use the correct user or sudo when appropriate.

#bsd#permission

EX_CONFIG

Configuration error.

Configuration is invalid or incomplete.

Fix configuration and restart the service.

Curl

4 entries

Could Not Resolve Host

Curl could not resolve the hostname.

DNS lookup failed for the given host.

Fix the hostname or DNS settings.
Use the correct domain or IP address.

#network#dns#curl

Failed to Connect

Failed to connect to host or proxy.

Host resolved, but TCP connection could not be established.

Open the port or start the service.
Fix firewall, proxy, or routing issues.

Operation Timeout

The request timed out.

The operation exceeded --max-time or connection timeouts.

Increase timeout values.
Optimize the server or reduce response size.

SSL Connect Error

SSL/TLS handshake failed.

TLS negotiation failed, often due to protocol or cert issues.

Use compatible TLS versions or ciphers.
Fix CA trust or server certificates.

#ssl#security#curl

HTTP

3 entries

Bad Request

Server cannot process the request.

Malformed syntax or invalid request data.

Fix the request format and resend.

#http#client-error

Not Found

Resource not found.

Server cannot find the requested path.

Correct the URL or restore the resource.

#http#not-found

Internal Server Error

Generic server-side error.

Server encountered an unexpected condition.

Fix the underlying server bug and redeploy.

#http#server-error

AI Powered, Non-Intrusive Terminal Assistant

TmuxAI enhances your terminal with AI-powered commands, automation, and contextual awareness while preserving your existing workflow. It's open-source, privacy-focused, and can be used with any terminal emulator.

curl -fsSL https://get.tmuxai.dev | bash