Implement echo

[kjloveless]

Mistakenly thought echo was a native program we could rely on...

Noticed that it functions like this currently:

echo $PATH
$PATH

Found this stackoverflow post when looking into this problem

Furthermore I found this function in Zig std

Looking at some other shells (bash & fish) we may want to expand environment variables before executing the utility.

[kjloveless]

const std = @import("std");

pub fn main() !void {
  var gpa = std.heap.GeneralPurposeAllocator(.{}){};
  const allocator = gpa.allocator();
  const env = try std.process.getEnvMap(allocator);

  var it = env.hash_map.iterator();
  while (it.next()) |entry| {
    const key = entry.key_ptr.*;
    const value = entry.value_ptr.*;
    std.debug.print("{s}: {s}\n", .{key, value});
  }
  std.debug.print("{s}", .{env.get("NAME").?});
}

Was messing around and came with the preceding snippet, should be useful in argument expansion.