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49 lines
1.8 KiB
Markdown
49 lines
1.8 KiB
Markdown
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# Spawning Processes
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Whenever Lune does not have the API you need as part of its built-in libraries, or when you want to
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use a program that already exists but interact with it from within Lune, you can use
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[`process.spawn`](../../api-reference/process.md#spawn).
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## Example
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This example calls out to the native "ping" program found in many operating systems, and parses its
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output into something more usable to us.
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This may look scary with lots of weird symbols, but, it's just some Lua-style pattern matching to
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parse the lines of "min/avg/max/stddev = W/X/Y/Z ms" that the ping program gives back to us.
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```lua copy
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print("Sending 4 pings to google 🌏")
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local result = process.spawn("ping", {
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"google.com",
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"-c 4",
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})
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if result.ok then
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assert(#result.stdout > 0, "Result output was empty")
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local min, avg, max, stddev = string.match(
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result.stdout,
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"min/avg/max/stddev = ([%d%.]+)/([%d%.]+)/([%d%.]+)/([%d%.]+) ms"
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)
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print(string.format("Minimum ping time: %.3fms", tonumber(min)))
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print(string.format("Maximum ping time: %.3fms", tonumber(max)))
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print(string.format("Average ping time: %.3fms", tonumber(avg)))
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print(string.format("Standard deviation: %.3fms", tonumber(stddev)))
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else
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print("Failed to send ping to google!")
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print(result.stderr)
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process.exit(result.code)
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end
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```
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Note that if the result of the subprocess was non-zero, meaning it errored and `ok` was set to
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`false`, we will also propagate the exit code of that subprocess using
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[`process.exit`](../../api-reference/process.md#exit). This will ensure that if our subprocess
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fails, our script will do the same, and let the user know with a proper exit code.
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## Conclusion
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This is the last page of the introduction book, for more specific usage and a full overview of all
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of the APIs that Lune provides, please check out the API Reference section in the sidebar. Enjoy! 🚀
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