lovelove工作

C13-Linux系统编程/fs/100days.c

@@ -0,0 +1,34 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+#define TIMESTRSIZE 128
+
+/**
+ * @brief    找出100天以后是哪一天
+ * @details
+ *
+ * @param    argc
+ * @param    argv
+ *
+ * @return  int
+ */
+int main(int argc, char **argv)
+{
+    time_t     stamp;
+    struct tm *tm;
+    char       timestr[TIMESTRSIZE];
+
+    time(&stamp);
+    tm = localtime(&stamp);
+    strftime(timestr, TIMESTRSIZE, "Now: %Y-%m-%d", tm);
+    puts(timestr);
+
+    tm->tm_mday += 100;
+    //  mktime 会先调整tm溢出的情况
+    mktime(tm);
+    strftime(timestr, TIMESTRSIZE, "100 days later: %Y-%m-%d", tm);
+    puts(timestr);
+
+    exit(0);
+}

C13-Linux系统编程/fs/atexit.c

@@ -0,0 +1,37 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+static void f1(void)
+{
+    puts("f1() is working!");
+}
+
+static void f2(void)
+{
+    puts("f2() is working!");
+}
+
+static void f3(void)
+{
+    puts("f3() is working!");
+}
+
+int main(int argc, char **argv)
+{
+    puts("Begin!");
+
+    atexit(f1);
+    atexit(f2);
+    atexit(f3);
+
+    puts("End!");
+
+    exit(0);
+}
+// out:
+// *[main][~/Linux-C-Notes/C13-Linux系统编程/fs]$ ./atexit
+// Begin!
+// End!
+// f3() is working!
+// f2() is working!
+// f1() is working!

C13-Linux系统编程/fs/check.c

@@ -0,0 +1,46 @@
+#include <crypt.h>
+#include <shadow.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+/**
+ * @brief    加密输入的密码并与shadow文件中的密码进行比较
+ * @details
+ *        !!! compile: gcc check.c -o check -lcrypt
+ *        !!! 需要root权限运行
+ *
+ * @param    argc
+ * @param    argv   [in]  用户名
+ *
+ * @return  int
+ */
+int main(int argc, char **argv)
+{
+    if (argc < 2)
+    {
+        fprintf(stderr, "Usage:...\n");
+        exit(1);
+    }
+
+    char        *input_pass;
+    struct spwd *shadowline;
+    char        *crypt_pass;
+
+    //* getpass()函数在输入密码时不会回显密码
+    input_pass = getpass("PassWord: ");
+
+    //* getspnam()函数通过用户名获取shadow文件中的密码
+    shadowline = getspnam(argv[1]);
+
+    //* 加密输入的密码
+    crypt_pass = crypt(input_pass, shadowline->sp_pwdp);
+
+    if (0 == strcmp(crypt_pass, shadowline->sp_pwdp))
+        puts("OK!");
+    else
+        puts("Error!");
+
+    exit(0);
+}

C13-Linux系统编程/fs/main1.c

@@ -0,0 +1,13 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, char **argv)
+{
+    printf("Hello, World!\n");
+
+    return 0;
+    /*
+     *  echo $?
+     *  0
+     */
+}

C13-Linux系统编程/fs/mydate.c

@@ -0,0 +1,109 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+#define TIMESTRSIZE 1024
+#define FMTSTRSIZE  1024
+
+/**
+ * @brief    mydate
+ * @details
+ *           Usage:
+ *               mydate [-H 12|24] [-y 2|4] [-m] [-d] [-M] [-S]
+ *           Options:
+ *               -y: year 2位,4位
+ *               -m: month
+ *               -d: day
+ *               -H: hour 12小时制,24小时制
+ *               -M: minute
+ *               -S: second
+ *
+ * @param    argc
+ * @param    argv
+ *
+ * @return  int
+ */
+int main(int argc, char **argv)
+{
+    time_t     stamp;
+    struct tm *tm;
+    char       timestr[TIMESTRSIZE];
+    int        c;
+    char       fmtstr[FMTSTRSIZE];
+    fmtstr[0] = '\0';
+    FILE *fp  = stdout;
+
+    time(&stamp);
+    tm = localtime(&stamp);
+
+    while (1)
+    {
+        //* 选项传参
+        // c = getopt(argc, argv, "H:y:MSmd");
+
+        //* 加'-'，接收非选项传参
+        c = getopt(argc, argv, "-H:y:MSmd");
+        if (c < 0)
+            break;
+
+        switch (c)
+        {
+            //* 非选项传参，返回1
+        case 1:
+            if (stdout == fp)   //! 先入为主
+            {
+                fp = fopen(argv[optind - 1], "w");
+                if (NULL == fp)
+                {
+                    perror("fopen()");
+                    fp = stdout;
+                }
+            }
+            break;
+
+        case 'H':
+            if (0 == strcmp(optarg, "12"))
+                strncat(fmtstr, "%I(%P) ", FMTSTRSIZE - 1);
+            else if (0 == strcmp(optarg, "24"))
+                strncat(fmtstr, "%H ", FMTSTRSIZE - 1);
+            else
+                fprintf(stderr,
+                        "Usage: %s [-H 12|24] [-y 2|4] [-m] [-d] [-M] [-S]\n",
+                        argv[0]);
+            break;
+
+        case 'M': strncat(fmtstr, "%M ", FMTSTRSIZE - 1); break;
+
+        case 'S': strncat(fmtstr, "%S ", FMTSTRSIZE - 1); break;
+
+        case 'y':
+            if (0 == strcmp(optarg, "2"))
+                strncat(fmtstr, "%y ", FMTSTRSIZE - 1);
+            else if (0 == strcmp(optarg, "4"))
+                strncat(fmtstr, "%Y ", FMTSTRSIZE - 1);
+            else
+                fprintf(stderr,
+                        "Usage: %s [-H 12|24] [-y 2|4] [-m] [-d] [-M] [-S]\n",
+                        argv[0]);
+            break;
+
+        case 'm': strncat(fmtstr, "%m ", FMTSTRSIZE - 1); break;
+
+        case 'd': strncat(fmtstr, "%d ", FMTSTRSIZE - 1); break;
+
+        default: break;
+        }
+    }
+
+    strncat(fmtstr, "\n", FMTSTRSIZE - 1);
+    strftime(timestr, TIMESTRSIZE, fmtstr, tm);
+
+    fputs(timestr, fp);
+
+    if (fp != stdout)
+        fclose(fp);
+
+    exit(0);
+}

C13-Linux系统编程/fs/timelog.c

@@ -0,0 +1,86 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <unistd.h>
+
+#define FNAME   "time.log"
+#define BUFSIZE 1024
+
+/**
+ * @brief    往文件里面输出时间戳
+ * @details
+ *           实例格式：2019-12-12 12:12:12
+ *
+ * @param    argc
+ * @param    argv
+ *
+ * @return  int
+ */
+int main(int argc, char **argv)
+{
+    FILE      *fp;
+    time_t     stamp;
+    struct tm *tm;
+    char       buf[BUFSIZE];
+    int        count = 0;
+
+    fp = fopen(FNAME, "a+");
+    if (fp == NULL)
+    {
+        perror("fopen()");
+        exit(1);
+    }
+
+    while (fgets(buf, BUFSIZE, fp) != NULL)
+        count++;
+
+    while (1)
+    {
+        stamp = time(NULL);
+
+        tm = localtime(&stamp);
+        if (NULL == tm)
+        {
+            perror("localtime()");
+            exit(1);
+        }
+
+        strftime(buf, BUFSIZE, "%Y-%m-%d %H:%M:%S", tm);
+
+        fprintf(fp, "%-4d%s\n", ++count, buf);
+
+        /*
+         *  加了sleep(1)之后就没有输出？
+         *  全缓冲
+         *  因为缓冲区没有满，没有刷新到文件里面
+         */
+        fflush(fp);
+
+        sleep(1);
+    }
+
+    fclose(fp);
+    exit(0);
+}
+
+//! 最终效果
+// *[main][~/Linux-C-Notes/C13-Linux系统编程/fs]$ ./test
+// ^C
+// *[main][~/Linux-C-Notes/C13-Linux系统编程/fs]$ cat time.log
+// 1   2024-05-11 21:53:26
+// 2   2024-05-11 21:53:27
+// 3   2024-05-11 21:53:28
+// 4   2024-05-11 21:53:29
+// 5   2024-05-11 21:53:30
+// *[main][~/Linux-C-Notes/C13-Linux系统编程/fs]$ ./test
+// ^C
+// *[main][~/Linux-C-Notes/C13-Linux系统编程/fs]$ cat time.log
+// 1   2024-05-11 21:53:26
+// 2   2024-05-11 21:53:27
+// 3   2024-05-11 21:53:28
+// 4   2024-05-11 21:53:29
+// 5   2024-05-11 21:53:30
+// 6   2024-05-11 21:53:35
+// 7   2024-05-11 21:53:36
+// 8   2024-05-11 21:53:37
+// 9   2024-05-11 21:53:38

C13-Linux系统编程/fs/username.c

@@ -0,0 +1,29 @@
+#include <pwd.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+/**
+ * @brief    用user id获取用户名
+ * @details
+ *
+ * @param    argc
+ * @param    argv
+ *
+ * @return  int
+ */
+int main(int argc, char **argv)
+{
+    if (argc < 2)
+    {
+        fprintf(stderr, "Usage: %s <user id>\n", argv[0]);
+        exit(1);
+    }
+
+    struct passwd *pwdline;
+
+    pwdline = getpwuid(atoi(argv[1]));
+
+    puts(pwdline->pw_name);
+
+    exit(0);
+}