cat

cat/cat.zig

@@ -0,0 +1,57 @@
+const std = @import("std");
+
+fn print(comptime format: []const u8, args: anytype) void {
+    const stdout = std.io.getStdOut().writer();
+    nosuspend stdout.print(format, args) catch return;
+}
+
+fn print_input() !void {
+   const stdin = std.io.getStdIn().reader();
+   var buffer: [4096]u8 = undefined;
+   while (true) {
+       const nbytes = try stdin.read(&buffer);
+       print("{s}", .{buffer[0..nbytes]});
+       if (nbytes == 0) break;
+   }
+}
+
+fn fatal(comptime format: []const u8, args: anytype) noreturn {
+    std.log.err(format, args);
+    std.process.exit(1);
+}
+
+const usage = "usage: cat [files]";
+
+pub fn main() anyerror!void {
+    const args = try std.process.argsAlloc(std.heap.page_allocator);
+
+    if (args.len <= 1) {
+        std.log.info("{s}", .{usage});
+        fatal("expected command argument", .{});
+    }
+
+    const files = args[1..];
+    for (files) |f| {
+        if (std.mem.eql(u8, f, "-")) {
+            try print_input();
+        }
+        else {
+            try print_file (f);
+        }
+    }
+}
+
+fn print_file(dest: []const u8) !void {
+   // open file and defer closing
+   var file = try std.fs.cwd().openFile(dest, .{ .mode = .read_only });
+   defer file.close();
+
+   // read file content and print everything
+   var buffer: [4096]u8 = undefined;
+   var nbytes : u64 = 0;
+   while (true) {
+       nbytes = try file.read(&buffer);
+       print("{s}", .{buffer[0..nbytes]});
+       if (nbytes == 0) break;
+   }
+}