tallge / Reference

Reference

Plain pages for things that are easier to look up than to remember. They work without JavaScript and print cleanly. The sheets listed on the downloads page are also available as PDF.

Git by task

Everyday git commands grouped by what you are trying to do, including how to undo things.

Regular expression syntax

JavaScript regex syntax: classes, anchors, quantifiers, groups, lookaround, flags and replacement tokens.

Cron syntax

The five crontab fields, special characters, shortcuts, and the mistakes that make jobs silently not run.

HTTP status codes

The status codes you actually meet, with the situations that produce them.

HTTP headers

Common request and response headers: caching, content, ranges, cookies, CORS and security headers.

Linux commands by task

Shell commands for files, text, processes, disks and basic network diagnostics, grouped by task.

Signals and exit codes

Unix signals with their numbers and default actions, shell exit codes such as 126, 127 and 137, and how services are stopped.

File permissions (chmod)

Unix permission bits in octal and symbolic form, common modes, special bits and umask.

CIDR and subnet sizes

IPv4 prefix sizes and masks, private and special ranges, and the IPv6 prefixes in common use.

Date and time formats

ISO 8601, RFC 3339, Unix time and HTTP dates, with the parsing traps in JavaScript and SQL.