Unix 타임스탬프 이해: 개발자 안내서

If you've worked with databases, APIs, or any system that tracks time, you've encountered Unix timestamps. This simple yet powerful concept is fundamental to how computers handle time. Let's demystify it.

유닉스 타임스탬프란 무엇입니까?

A Unix timestamp (also called "epoch time" or "POSIX time") is the number of seconds that have elapsed since January 1, 1970, 00:00:00 UTC. This moment is called the "Unix epoch."

Example: The timestamp 1705276800 represents January 15, 2024, 00:00:00 UTC. It's simply the count of seconds since the epoch.

Why 1970? When Unix was being developed in the early 1970s, developers needed a starting point. January 1, 1970 was chosen as a convenient, recent date that predated the system's creation.

개발자가 타임스탬프를 좋아하는 이유

Language-agnostic: A timestamp means the same thing in JavaScript, Python, Java, or any language
Timezone-independent: Timestamps are always UTC, eliminating timezone confusion
Easy to compare: Comparing two timestamps is just comparing two numbers
Easy math: Add 86400 to get tomorrow. Subtract 3600 to go back an hour.
Compact storage: A 32-bit integer stores a date more efficiently than a string

타임스탬프 작업

자바스크립트

                // Current timestamp (in seconds)

                const timestamp = Math.floor(Date.now() / 1000);

                // Timestamp to Date

                const date = new Date(timestamp * 1000);

                // Date to timestamp

                const ts = Math.floor(new Date('2024-01-15').getTime() / 1000);

⚠️ JavaScript 문제

JavaScript's Date.now() returns milliseconds, not seconds. Always divide by 1000 for Unix timestamps.

파이썬

                import time

                from datetime import datetime

                # Current timestamp

                timestamp = int(time.time())

                # Timestamp to datetime

                dt = datetime.fromtimestamp(timestamp)

                # Datetime to timestamp

                ts = int(datetime(2024, 1, 15).timestamp())

PHP

                // Current timestamp

                $timestamp = time();

                // Timestamp to date

                $date = date('Y-m-d H:i:s', $timestamp);

                // Date to timestamp

                $ts = strtotime('2024-01-15');

2038년 문제

⚠️ Critical Issue: On January 19, 2038, at 03:14:07 UTC, 32-bit Unix timestamps will overflow. Systems still using 32-bit signed integers for time will see dates wrap around to 1901 or crash entirely.

The maximum value of a signed 32-bit integer is 2,147,483,647 seconds after the epoch, which equals January 19, 2038. After this moment, the counter overflows.

Modern systems address this by using 64-bit timestamps, which won't overflow for about 292 billion years. Most programming languages and databases have already transitioned.

일반적인 함정

1. 시간대 혼란

Timestamps are always UTC. When converting to local time, remember to apply the timezone offset:

                // Wrong: treats UTC timestamp as local time

                new Date(1705276800000) // may show wrong time

                // Right: explicitly handle timezone

                new Date(1705276800000).toLocaleString('en-US', {timeZone: 'America/New_York'})

2. 밀리초 대 초

JavaScript uses milliseconds. Unix traditionally uses seconds. Always check which your system expects:

Unix timestamp: 1705276800 (10 digits)
JavaScript timestamp: 1705276800000 (13 digits)

3. 부정적인 타임스탬프

Dates before 1970 have negative timestamps. December 31, 1969 at 23:59:59 UTC is timestamp -1. Some systems don't handle negative timestamps correctly.

4. 윤초

Unix time doesn't account for leap seconds. It assumes every day is exactly 86,400 seconds. For most applications this doesn't matter, but for high-precision time systems, consider NTP or TAI.

유용한 타임스탬프 값

                Seconds in a minute: 60

                Seconds in an hour: 3,600

                Seconds in a day: 86,400

                Seconds in a week: 604,800

                Seconds in a year: 31,536,000 (approximately)

                // Quick math

                tomorrow = now + 86400

                nextWeek = now + 604800

                yesterday = now - 86400

타임스탬프와 날짜 문자열을 사용하는 경우

Use timestamps for:

Database storage (consistent, sortable, efficient)
API communication (no timezone ambiguity)
Log files (easy to compare)
Session expiration, cache invalidation

Use date strings (ISO 8601) for:

Human-readable logs
User-facing interfaces
When timezone information must be preserved

🔧 타임스탬프를 변환해야 합니까?

Use our free Unix Timestamp Converter to convert between timestamps and human-readable dates.

타임스탬프 변환기 열기 →

결론

Unix timestamps are beautifully simple: count seconds from a fixed point. This simplicity makes them perfect for storing, comparing, and transmitting time data. Just remember the key conversions, watch out for the millisecond/second distinction, and always think in UTC.

With timestamps in your toolkit, handling time in any application becomes straightforward.

⏰ Unix 타임스탬프 이해: 개발자 가이드