From 3886749b1c8d79d4701bf6b8e66249c4e1491648 Mon Sep 17 00:00:00 2001
From: Richard Qin <richard.qin.x@gmail.com>
Date: Sun, 4 Jan 2026 18:06:31 +0800
Subject: dev(shell): implement basic shell tools fixed(file-system): fixed
 read and write bugs

---
 src/user/grep.cc | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 src/user/grep.cc

(limited to 'src/user/grep.cc')

diff --git a/src/user/grep.cc b/src/user/grep.cc
new file mode 100644
index 0000000..5ed61b4
--- /dev/null
+++ b/src/user/grep.cc
@@ -0,0 +1,68 @@
+#include "ulib/stdio.h"
+#include "ulib/stdlib.h"
+#include "ulib/string.h"
+#include "user/user.h"
+#include "common/fcntl.h"
+
+char buf[1024];
+
+void grep(char *pattern, int fd)
+{
+    int n, m;
+    char *p, *q;
+
+    m = 0;
+    while ((n = read(fd, buf + m, sizeof(buf) - m - 1)) > 0)
+    {
+        m += n;
+        buf[m] = '\0';
+        p = buf;
+        while ((q = strchr(p, '\n')) != 0)
+        {
+            *q = 0;
+            if (strstr(p, pattern) != 0)
+            {
+                printf("%s\n", p);
+            }
+            p = q + 1;
+        }
+        if (p == buf)
+            m = 0;
+        if (m > 0)
+        {
+            m -= p - buf;
+            memmove(buf, p, m);
+        }
+    }
+}
+
+int main(int argc, char *argv[])
+{
+    int fd, i;
+    char *pattern;
+
+    if (argc < 2)
+    {
+        printf("Usage: grep pattern [file...]\n");
+        exit(1);
+    }
+    pattern = argv[1];
+
+    if (argc == 2)
+    {
+        grep(pattern, 0); // stdin
+        exit(0);
+    }
+
+    for (i = 2; i < argc; i++)
+    {
+        if ((fd = open(argv[i], O_RDONLY)) < 0)
+        {
+            printf("grep: cannot open %s\n", argv[i]);
+            exit(1);
+        }
+        grep(pattern, fd);
+        close(fd);
+    }
+    exit(0);
+}
\ No newline at end of file
-- 
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