Tag

error fix

39 posts

Testing

ShellCheck SC2181 Check Exit Code Directly Explained

Fix ShellCheck SC2181: test a command's exit status directly with if cmd or if ! cmd instead of checking $? afterwards, and when $? is still right.

6 min read

Security

Security Error Sudo Is Not in the Sudoers File Fully

Fix user is not in the sudoers file: add the user to the sudo or wheel group as root, use su or recovery mode, and check sudoers syntax with visudo.

6 min read

Regular Expressions

Regex Error Invalid Preceding Regular Expression Fully

Fix grep and sed's invalid preceding regular expression error: a quantifier with nothing to repeat, BSD versus GNU differences, braces and macOS quirks.

6 min read

Debugging

Debugging Unexpected Output From Pipes and Buffers

Debug unexpected pipe output: stdio buffering with a pipe, stdbuf and unbuffer, python -u, grep --line-buffered, and interleaved stderr.

6 min read

SSH and Networking

SSH Connection Timed Out and Firewall Problems Fully

Fix SSH Connection timed out: tell it from refused, trace the path with nc and traceroute, check firewalls and security groups, and set ConnectTimeout.

6 min read

SSH and Networking

SSH Connection Refused and What to Check First Explained

Fix SSH connection refused: confirm sshd is running and listening, the port and address, firewall rules, and how it differs from a timeout.

6 min read

SSH and Networking

SSH Permission Denied Publickey Causes and Fixes Fully

Fix SSH Permission denied (publickey): read ssh -v output, check the key, the agent, file permissions on both sides, the user name and sshd logs.

6 min read

Go Exec Executable File Not Found in PATH Error Fully

Fix the Go error exec executable file not found in PATH: why exec.Command needs the program on PATH, LookPath, absolute paths, containers and services.

6 min read

Databases

PostgreSQL Error Peer Authentication Failed With Every Cause

Fix PostgreSQL peer authentication failed for user: pg_hba.conf rules, Unix socket versus TCP, matching OS and database user names, and a safe change.

6 min read

Testing

ShellCheck SC2046 Quote to Prevent Word Splitting Explained

Fix ShellCheck SC2046: quote command substitutions to prevent word splitting, with ls, find and git examples, and safer arrays and mapfile patterns.

6 min read

Testing

ShellCheck SC2155 Declare and Assign Separately Explained

Fix ShellCheck SC2155: why local x=$(cmd) hides the command's exit status, and how to declare and assign on separate lines so set -e and checks still work.

6 min read

CI/CD

Jenkins Error Script Returned Exit Code 127 With Every Cause

Fix Jenkins script returned exit code 127: command not found, agent PATH differences, missing tools, Windows line endings and wrong interpreters.

6 min read