usr: touch, tr, rev, cut, uniq

    /# ls -l /bin > b
    /# cut -d \s -f 1 b | uniq -c
    52 -

- touch FILE...: gbfs has no timestamps (an MBC5 cart has no RTC), so touch
  does the half that means something here - make an empty file. O_APPEND is
  exactly right: it creates, and it does not truncate what is already there.
- tr [-d] SET1 [SET2]: ranges (a-z), -d to delete, and a short SET2 padded
  with its last character, like tr(1). ASCII only - a 128-entry map.
- rev, uniq [-c]: one line each, from a file or stdin like the other filters.

Two things the tests caught. A bare "-" is a SET, not a flag, so `tr . -`
has to skip flag-matching only when a letter follows the dash. And uniq
compared an empty "line" against the last run at EOF and flushed a phantom
blank one - a stray "1" in uniq -c output.

tr and cut also take \s \t \n \r escapes, because the shell has no quoting:
`-d ' '` arrives as three tokens, so a space or tab delimiter was simply
untypeable. Shell quoting would be the better fix; this makes the tools
usable today without touching the parser.

Banks 49-53; 10 program slots left in the 1 MB ROM.

1 files changed, 26 insertions, 0 deletions

diff --git a/usr/touch.c b/usr/touch.c
new file mode 100644
index 0000000..4f5ba89
--- /dev/null
+++ b/usr/touch.c
@@ -0,0 +1,26 @@
+#include "gbos.h"
+/* touch FILE...: create FILE if it does not exist, leave it alone if it does.
+ *
+ * There are no timestamps in gbfs (no RTC on an MBC5 cart), so touch only does
+ * the half that means anything here: make an empty file. O_APPEND is exactly
+ * right for it - it creates, and it does NOT truncate what is already there. */
+void main(void) {
+    char *argv[8];
+    unsigned char argc = argv_parse(argv, 8);
+    unsigned char i, fd;
+    if (argc < 1) {
+        puts("usage: touch FILE...");
+        nl();
+        sexit(2);
+    }
+    for (i = 0; i < argc; i++) {
+        fd = open(argv[i], O_APPEND);
+        if (fd > 3) {
+            puts("touch: cannot create ");
+            puts(argv[i]);
+            nl();
+            continue;
+        }
+        close(fd);
+    }
+}