Running a Compiled Rust Binary with Cron
A compiled Rust binary needs no runtime — just give cron the absolute path (e.g. `/opt/app/target/release/mytask`). `cd` first only if it reads relative files, and export any env vars it expects.
The crontab line
0 4 * * * /opt/app/target/release/mytask >> /var/log/mytask.log 2>&1
There is no interpreter to source — a release build is a self-contained executable. Point cron straight at it.
Environment variables
Cron starts with an almost-empty environment. If your program reads config via env::var (database URLs, API keys), set them in the crontab: 0 4 * * * DATABASE_URL=postgres://... /opt/app/target/release/mytask.
Working directory
If the binary opens files by relative path (a .env or data file), cd into its directory first: cd /opt/app && ./target/release/mytask.
FAQ
How do I run a Rust program from cron?
Build with cargo build --release and point cron at the binary: 0 4 * * * /opt/app/target/release/mytask. No runtime needed.
Why can't my Rust cron job find its environment variables?
Cron doesn't load your shell profile. Set the vars inline in the crontab line or load a .env from the working directory.
Should I use the debug or release binary in cron?
Use target/release (built with cargo build --release) — it's optimized and the path is stable for scheduled runs.