sh: handle backspace in readline; prompt is now '#'

readc() returning $08/$7F now drops the last char from the command buffer
(and emits one $08 so the terminal erases it) instead of storing the raw
byte. Previously "lz<bksp>s" left the buffer as "lz\x08s", so the command
"ls" was reported "not found" even though the screen showed "ls".
Also change the shell prompt from '$' to '#'.

osk: B button types the selected key SHIFTED (uppercase a-z). A types the
key as shown (lowercase/digit/symbol); B on a letter subtracts 32 for the
uppercase glyph (the font already has A-Z). Non-letters are unchanged.

1 files changed, 5 insertions, 1 deletions

diff --git a/c/sh.c b/c/sh.c
index b1bf630..df2c5e9 100644
--- a/c/sh.c
+++ b/c/sh.c
@@ -104,13 +104,17 @@ void main(void) {
         unsigned char nt, i, pipepos, c, bg;
         /* reap finished background jobs */
         { unsigned char p; while ((p = reap())) { putc('['); putu(p); puts(" done]"); nl(); } }
-        puts(cwd); puts("$ ");
+        puts(cwd); puts("# ");
         /* read a line (echoing), stop at newline; exit on EOF */
         i = 0;
         for (;;) {
             c = readc();
             if (c == EOF) poweroff();
             if (c == '\r' || c == '\n') { nl(); break; }
+            if (c == 8 || c == 127) {            /* backspace: drop last char */
+                if (i > 0) { i--; putc(8); }
+                continue;
+            }
             if (i < 79) { line[i++] = c; putc(c); }
         }
         line[i] = 0;