wolfcw/libfaketime

Health v2 · maintenance only

Adoption not part of the score

3106 stars · 377 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-29, confidence not recorded

libfaketime is an LD_PRELOAD library that intercepts system calls retrieving the current date and time, reporting faked times to a single application without changing the system clock. It ships with a 'faketime' command-line wrapper and supports absolute dates, relative offsets, and deterministic time sequences.

Use cases

• fake the system time for a single program
• make builds reproducible with fixed timestamps
• debug expired SSL certificate issues
• test software for year-2038 compliance
• run an application with a date in the past or future
• mock time in tests without changing the system clock

When to choose

• you need to control the time a single process sees without root or system-wide changes
• you want reproducible builds with deterministic timestamps
• you are debugging time-dependent behavior like certificate expiry

When to avoid

• the target binary is statically linked or setuid, since LD_PRELOAD cannot intercept it
• you need to fake time on Windows or non-UNIX platforms
• you need monotonic clock faking for JVM apps without extra configuration

Facets

library · maturity active

date-time testing developer-tools developer-tools testing cli cpp c ld-preload time-mocking reproducible-builds system-call-interception faketime command-line linux macos

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