Shell

The kernel shell runs inside kernel_main() and combines filesystem operations, diagnostics, development tools, and network inspection. It is currently a VGA text-mode interface.

Runtime loop

The shell polls Ethernet before reading keyboard input, so ARP and ICMP packets can be handled while the user is idle:

while (1) {
    eth_dispatch();
    if (!keyboard_available()) {
        asm volatile("hlt");
        continue;
    }
    char c = keyboard_getchar();
    /* append input and dispatch complete lines */
}

Network commands

pci

Scan PCI bus 0 and print vendor/device IDs, classes, IRQ values, and discovered devices. Use this first when the NIC is not detected.

nicinfo

Print RTL8139 I/O base, IRQ, MAC address, command state, interrupt state, current buffer pointer, and software RX position.

arp

Print valid entries in the eight-entry IP-to-MAC cache. The cache is initially empty and is populated by received ARP packets.

ping <ip>

Send four ICMP echo requests to a dotted IPv4 address. In the default QEMU setup, test the gateway with:

ping 10.0.2.2

Each request uses a 64-byte ICMP message and waits while the kernel polls Ethernet frames. A cache miss first sends an ARP broadcast. Invalid addresses print ping: invalid IP; missing ARP or transmit support prints a network error.

Filesystem and development commands

The remaining commands include ls, cd, pwd, mkdir, touch, rm, rmdir, cat, write, append, hexdump, edit, nasm, user, lex, parse, and occ. Use help or help more inside OaSis for the complete current list.

Diagnostics

• dmesg: dump the circular kernel log.
• uptime: print PIT tick-based uptime.
• meminfo: print physical memory usage.
• taskinfo: print task state.
• syscall: print the system call table.

The build and testing guide contains a complete networking smoke test.

Previous shell implementation notes

The sections below retain the detailed filesystem and application command notes.

shell runs as an infinite loop in kernel_main() (src/kernel/core/kernel.c).

Loop main

while (1) {
 char c = keyboard_getchar();

 if (c == '\n') {
 input[index] = 0; // null-terminate
 vga_putc('\n');
 vga_refresh_cursor();

 // parse command
 if (strcmp(input, "help") == 0) { ... }
 else if (starts_with(input, "edit ")) { ... }
 else if (starts_with(input, "cat ")) { ... }
 // ... all commands ...
 else if (index != 0) {
 vga_print("unknown command: ");
 vga_print(input);
 vga_print("\n");
 }

 index = 0;
 // print prompt lagi
 vga_print("oasis"); vga_putc('(');
 VFS_getcwd(cwd_buf, sizeof(cwd_buf));
 vga_print(cwd_buf); vga_putc(')'); vga_print("> ");
 vga_refresh_cursor();
 }
 else if (c == '\b') {
 if (index > 0) { index--; vga_putc('\b'); vga_refresh_cursor(); }
 }
 else {
 if (index < INPUT_MAX - 1) { input[index++] = c; vga_putc(c); vga_refresh_cursor(); }
 }
}

INTERNAL_MAX = 256.

Command reference

Help

print the command list. if help more show all commands, including less common commands.

Ls [path]

list directory. parse output from VFS_list():

• if type ‘d’ (directory): color kuning (VGA_color_YELLOW)
• if type ‘f’ (file): color putih

output from VFS_list format: d nama_dir\nf nama_file\n

if (out[j] == 'd') {
 vga_set_color(VGA_COLOR_YELLOW, VGA_COLOR_BLACK);
 j += 2; // skip "d "
 while (out[j] != 0 && out[j] != '\n') vga_putc(out[j++]);
 if (out[j] == '\n') j++;
 vga_set_color(15, VGA_COLOR_BLACK);
 vga_print(" "); // spacing antar item
}

Cd

call VFS_chdir(arg). if return != 0, print “cd: failed”.

Pwd

call VFS_getcwd(pathbuf, sizeof(pathbuf)), print the result.

Mkdir

call VFS_mkdir(arg).

Touch

call VFS_create(arg).

Rm

call VFS_unlink(arg).

Rmdir

call VFS_rmdir(arg).

Cat

int fd = VFS_open(arg, VFS_O_READ);
if (fd < 0) { vga_print("cat: open failed\n"); }
else {
 char rbuf[128]; int n;
 while ((n = VFS_read(fd, rbuf, sizeof(rbuf) - 1)) > 0) {
 rbuf[n] = 0;
 vga_print(rbuf);
 }
 vga_print("\n");
 VFS_close(fd);
}

Write

int fd = VFS_open(arg, VFS_O_WRITE | VFS_O_CREATE | VFS_O_TRUNC);
if (fd >= 0) {
 VFS_write(fd, text, strlen(text));
 VFS_close(fd);
}

Append

the same as write, but uses VFS_O_APPEND.

Echo

print text + newline.

Hexdump

read file, print tiap byte as hex.

Edit

call editor_run(arg).

Nasm

call asm_run_file(arg).

User

call run_user_test(arg).

Occ

call run_occ(arg).

Dmesg

call log_dump().

Syscall

print tabel syscall.

Uptime

timer_get_ticks() / 100 = detik sejak boot.

Meminfo

print PMM_get_free_pages() + total memory.

Taskinfo

print all task + status + stack + eip.