FGELEV(1)

👑 FGELEV(1) — the FlightGear man pages, but make it a group chat

okay bestie, sit down, hydrate, and let me tell you about fgelev 💅 she lives in the FlightGear manual pages and she is so much more useful than her boring name suggests.

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✨ NAME ✨

fgelev — compute FlightGear scenery elevation for a given list of points 🏔️

like. she takes your points. she tells you how high up they are. no cap.

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🦋 SYNOPSIS 🦋

fgelev [--expire num] [--print-solidness] [--fg-root rootdir]
[--fg-scenery scenerydir] [--tile-file osgbfilename] [--use-vpb]

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💖 DESCRIPTION 💖

so fgelev is a standalone utility, right? you hand her a list of points on standard input, and she prints the corresponding elevation for each of them on standard output. that's the whole gig. she's an icon, she's a legend, she does one thing.

and because she's generous 💅 she can optionally also tell you whether the material covering that point is solid or not. the range. the versatility.

🌸 the input, bestie

the list of points has to look exactly like this:

id lon lat

where:

• id — an arbitrary identifier for the point (you make it up, she doesn't care, she's not judging 🫶)
• lon — the longitude of the point
• lat — the latitude of the point

and the hemisphere lore: positive longitudes (latitudes) correspond to points located in the Eastern (Northern) hemisphere, while negative ones correspond to points located in the Western (Southern) hemisphere. it's giving compass energy 🧭

🎀 the output, bestie

the list of elevations she hands back looks like this:

id: elev solid

where:

• id — the identifier of the point you passed as input (she returns it, she remembers, she's thoughtful)
• elev — the elevation of the point in meters, or -1000 if the elevation of the given point was not found 😭
• solid — and this one's conditional, so pay attention:
  • the string solid if the parameter --print-solidness was passed to fgelev and the material covering the point is solid
  • the string - if the parameter --print-solidness was passed to fgelev and the material covering the point is not solid
  • absent if the parameter --print-solidness was not passed to fgelev (she simply doesn't bring it up, periodt)

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💅 OPTIONS 💅

• --expire num — to speed up elevation data retrieval, fgelev uses an internal cache. this option lets you specify the number of requests after which, if a point was not queried in them, it should be marked as expired. by default, fgelev expires points not queried in the last 10 requests. she's cleaning house, respectfully 🧹
• --print-solidness — require fgelev to print the solidness of the material covering the queried point. see the DESCRIPTION section for more details. yes the section you just read. go back. it's fine. 💖
• --fg-root rootdir — set the FlightGear data root directory ($FG_ROOT) to rootdir. if this option is not set, fgelev uses the path specified in the FG_ROOT environment variable or, absent that, the FlightGear data directory chosen at the time the program was compiled. the fallback chain is giving eldest-sibling energy 🫶
• --fg-scenery scenerydir — set the FlightGear scenery directory ($FG_SCENERY) to scenerydir. if this option is not set, fgelev uses the path specified in the FG_SCENERY environment variable or, absent that, the Scenery subdirectory inside $FG_ROOT. iconic nesting behaviour 🌈
• --tile-file osgbfilename — use a specific tile file when searching for elevation details, instead of scanning through the whole world. like, why search the entire planet when you already know where to look? main character efficiency ⭐
• --use-vpb — if specified, enables WS3.0 scenery behaviour, searching under the vpb/ subdirectory. new scenery era unlocked 🔥

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💀 EXIT STATUS 💀

• fgelev exits with EXIT_SUCCESS on success 💖
• fgelev exits with EXIT_FAILURE if it is unable to read data from standard input or to load the scenery 😭

ngl bestie, those are the only two outcomes. she either ate or she didn't. no in-between, no grey area.

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🌸 ENVIRONMENT 🌸

• FG_ROOT — if FG_ROOT is set and --fg-root is not set, it specifies the root data directory to use.
• FG_SCENERY — if FG_SCENERY is set and --fg-scenery is not set, it specifies the scenery directory to use.

reminder: the command-line option always wins the vibe check. the env var is only stepping in when the flag didn't show up 👑

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🫶 SEE ALSO 🫶

• fgfs(1)

like, go say hi to the big one. she's the whole flight sim. fgelev is just her extremely competent little sister 🧚

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mwah 💋 that's the page! brought to you by the FlightGear girlies, dated 2020-11-15, in the FGELEV(1) era of the manual. stay elevated, bestie 🎀✨