Checking if file exists and creating if not | Zig Programming Language | Page 1

foggy garnet Jun 21, 2024, 3:25 PM

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Could I get a quick sanity check on this? Thanks.

    const agent_file = fs.openFileAbsolute(agent_path, .{ .mode = .read_only }) catch |err| switch (err) {
        error.FileNotFound => blk: {
            const file = try fs.createFileAbsolute(agent_path, .{});
            errdefer file.close();
            try file.writeAll(y3_plist);
            log.info("y3 service installed: {s}", .{agent_path});
            break :blk file;
        },
        else => {
            log.err("failed to open {s}: {s}", .{ agent_path, @errorName(err) });
            return err;
        },
    };
    defer agent_file.close();

floral solar Jun 21, 2024, 3:27 PM

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std.fs.cwd().createFile(path, .{ ... })

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The create in the name means that it will create it if it doesn't exist.

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Whereas the open versions error in that case.

foggy garnet Jun 21, 2024, 3:29 PM

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oh and i don't need to capture the happy path, edited

foggy garnet Jun 21, 2024, 3:34 PM

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floral solar `std.fs.cwd().createFile(path, .{ ... })`

this overwrites, correct?

visual juniper Jun 21, 2024, 6:35 PM

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foggy garnet this overwrites, correct?

yea but it wont if you do .truncate = false

stiff plank Jun 21, 2024, 6:54 PM

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fyi .truncate = false won't append

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you'll need to seek to the end of the file manually

foggy garnet Jun 21, 2024, 8:37 PM

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so if I don't want to modify a file that already exists, open first is the correct approach?

#Checking if file exists and creating if not