Date & Time Formatting Cheat Sheet (PHP vs Linux vs Ruby/Rails vs Standards)

data-format-cheatsheet.md

Date & Time Formatting Cheat Sheet (PHP vs Linux vs Ruby/Rails vs Standards)

This guide provides equivalent date/time format strings across popular environments (PHP, Linux, Ruby, etc.), with examples and tips. Also includes standard formats like ISO 8601 and RFC 2822.

Common Display Formats

Format Purpose	PHP Format	Linux/Ruby/POSIX Format	Example Output
Full Date/Time	d-m-Y H:i T	%d-%m-%Y %H:%M %Z	05-07-2025 14:23 CEST
Short Date	d-m-Y	%d-%m-%Y	05-07-2025
Long Date	l, j F Y	%A, %-d %B %Y	Saturday, 5 July 2025
Time Only	H:i T	%H:%M %Z	14:23 CEST

Use %e (or %-d) instead of %d for day without leading zero in POSIX-based formats. PHP uses j.

Format Specifier Reference

Description	PHP	POSIX strftime (Linux, Ruby, Python)
Year (4-digit)	Y	%Y
Year (2-digit)	y	%y
Month (2-digit)	m	%m
Month (short name)	M	%b
Month (full name)	F	%B
Day (2-digit)	d	%d
Day (no leading zero)	j	%e or %-d
Weekday (short)	D	%a
Weekday (full)	l	%A
Hour (24h)	H	%H
Hour (12h)	h	%I
Minutes	i	%M
Seconds	s	%S
AM/PM	A/a	%p
Timezone (abbreviation)	T	%Z
Timezone (offset)	P	%z

Standardized Formats

Format Name	Format String / Spec	Example Output	Notes
ISO 8601	Y-m-d\TH:i:sP (PHP) %Y-%m-%dT%H:%M:%S%z (POSIX)	2025-07-05T14:23:00+02:00	Canonical international format (sortable)
RFC 2822	r (PHP) %a, %d %b %Y %H:%M:%S %z	Sat, 05 Jul 2025 14:23:00 +0200	Used in email headers
Unix Timestamp	U (PHP) %s (GNU date only)	1751814180	Seconds since 1970-01-01 UTC

Usage Examples

PHP

echo date("d-m-Y H:i T"); // 05-07-2025 14:23 CEST
echo date("c");           // ISO 8601
echo date("r");           // RFC 2822

Linux

date "+%d-%m-%Y %H:%M %Z"
date --iso-8601=seconds

Ruby

Time.now.strftime("%d-%m-%Y %H:%M %Z")
Time.now.iso8601
Time.now.rfc2822

Tip

For maximum clarity, always show timezone abbreviation (%Z) or offset (%z), especially in global apps or transactional logs.