In this blog we will see how to run a child process from a zig program. There are two std lib functions that allows us to do this - std.process.run() and std.process.spawn(). Lets see how we can use both.
Method 1: std.process.run()
The run function allows us to run a process without much hassle. The following program runs ls -l and prints out the output in stdout. ls is a linux command. If you are on windows, you can use dir instead.
// runprocess__main.zig
const std = @import("std");
pub fn main(init: std.process.Init) !void {
const argv = [_][]const u8{ "ls", "-l" };
const result = try std.process.run(init.gpa, init.io, .{ .argv = &argv });
defer init.gpa.free(result.stderr);
defer init.gpa.free(result.stdout);
var buffer: [1024]u8 = undefined;
var file_writer = std.Io.File.Writer.init(.stdout(), init.io, &buffer);
var stdout_writer = &file_writer.interface;
try stdout_writer.print("{s}", .{result.stdout});
try stdout_writer.flush();
}
We can compile the program using zig build-exe runprocess__main.zig. Upon execution, this program will print the contents of current directory.
Method 2: std.process.spawn()
The spawn function gives us fine-grained control over the process.
// runprocessspawn_main.zig
const std = @import("std");
pub fn main(init: std.process.Init) !void {
const argv = [_][]const u8{
"ls",
"-l",
};
var child = try std.process.spawn(init.io, .{
.argv = &argv,
.stdin = .inherit,
.stdout = .inherit,
.stderr = .inherit,
});
_ = try child.wait(init.io);
}
We can compile the program using zig build-exe runprocessspawn__main.zig. Upon execution, this program will print the contents of current directory.
Thanks for reading. To be continued.
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