could not write bytes broken pipe

本文解决了一个在Ubuntu 12.04中遇到的问题,即登录时出现'couldnotwritebytesbrokenpipe'错误,并且在tt2终端下执行ls命令失败。问题原因在于/etc/profile文件中的PATH变量被误写为$PAHT。

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刚装好ubuntu,配置了下java

结果重启后进入到登录界面,

输入密码后就出现了如题所示错误:

could not write bytes broken pipe,

不过tt2还是可以进去的,

只是输入ls的时候提示没有找到,

瞬间觉醒,

查看了下/etc/profile:

$PATH被写成了$PAHT;

进入tt2修改之就搞定了。

引起该错的原因可能有多种,

所以要对好入座。


操作系统:Ubuntu 12.04

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/wait.h> #include <sys/types.h> #include <signal.h> #define MAX_INPUT_SIZE 1024 #define MAX_ARGS 64 void execute_command(char **args); /* 执行命令 */ int main() { char input[MAX_INPUT_SIZE] = {0}; /* 存储用户输入缓冲区 */ char *args[MAX_ARGS] = {NULL}; /* 命令参数 */ char *token = NULL; /* 分割字符串 */ int arg_count = 0; /* 参数计数器 */ while (1) { printf("myshell > "); fflush(stdout); /* 获取输入, 处理 EOF */ if (fgets(input, sizeof(input), stdin) == NULL) { break; } /* 移除换行符 */ input[strcspn(input, "\n")] = '\0'; /* 处理 exit 命令 */ if (strcmp(input, "exit") == 0) { printf("Exiting shell...\n"); break; } /* 解析命令和参数 */ token = strtok(input, " "); while (token != NULL && arg_count < MAX_ARGS - 1) { args[arg_count++] = token; token = strtok(NULL, " "); } args[arg_count] = NULL; /* 执行命令 */ execute_command(args); } return 0; } /* 执行命令函数 */ void execute_command(char **args) { /* 检查是否为内置命令 */ if (strcmp(args[0], "stop") == 0) { printf("Error: 'stop' is not a command. It should appear in program output.\n"); return; } pid_t pid = 0; int pipefd[2] = {0}; if (pipe(pipefd) == -1) { perror("pipe"); exit(EXIT_FAILURE); } pid = fork(); if (pid == -1) { perror("fork"); exit(EXIT_FAILURE); } else if (pid == 0)/* 子进程 */ { /* 关闭读取端 */ close(pipefd[0]); /* 重定向输出到管道 */ dup2(pipefd[1], STDOUT_FILENO); close(pipefd[1]); /* 执行命令 */ execvp(args[0], args); /* 执行失败 */ fprintf(stderr, "myshell: %s: command not found\n", args[0]); exit(EXIT_FAILURE); } else /* 父进程 */ { close(pipefd[1]); /* 关闭写入端 */ char buffer[MAX_INPUT_SIZE] = {0}; /* 输出缓冲区 */ ssize_t bytes_read = 0; /* 读取字节数 */ ssize_t total_printed = 0; /* 已打印字节数 */ char *stop_pos = strstr(buffer, "stop"); /* 检测输出中是否包含 stop */ /* 读取子进程输出 */ while ((bytes_read = read(pipefd[0], buffer, sizeof(buffer)-1)) > 0) { /* 确保字符串终止 */ buffer[bytes_read] = '\0'; /* 检测输出中是否包含 stop */ if (stop_pos) { /* 1、打印 stop 之前的内容 */ size_t keep_len = stop_pos - buffer; if (keep_len > 0) { printf("%.*s", (int)keep_len, buffer); fflush(stdout); } /* 2、打印stop本身 */ printf("stop"); fflush(stdout); /* 3、终止子进程并打印消息 */ kill(pid, SIGTERM); printf("\nReceived 'stop' in output. Terminating child process.\n"); fflush(stdout); /* 跳过后续处理 */ continue; } else /* 未检测到 stop 时正常打印输出 */ { printf("%s", buffer); fflush(stdout); } } close(pipefd[0]); /* 关闭读取端 */ waitpid(pid, NULL, 0); /* 等待子进程结束 */ } } 这是我的主要功能程序 #include <stdio.h> int main() { for (int i = 0; i < 5; i++) { printf("count: %d\n", i); if (i == 3) { printf("stop"); } } printf("This line should not be printed.\n"); return 0; } 这是我的测试程序 现在运行了./main后,输入以下内容: myshell > ./te myshell: ./te: command not found myshell > ./test count: 0 count: 1 count: 2 count: 3 stop Received 'stop' in output. Terminating child process. myshell > cat test.c cat: cat: No such file or directory cat: cat: No such file or directory #include <stdio.h> int main() { for (int i = 0; i < 5; i++) { printf("count: %d\n", i); if (i == 3) { printf("stop Received 'stop' in output. Terminating child process. myshell > 为什么会输出两个cat再输出test.c中的内容
08-08
/*! * ************************************************************************************************* * @copyright(c) 2008-2025 Shenzhen TP-LINK Technologies Co.Ltd. * * @file http.c * @brief * * @author huyushuai * @version 1.0.0 * @date 2025-08-08 * ************************************************************************************************* */ /**************************************************************************************************/ /* INCLUDE_FILES */ /**************************************************************************************************/ #include <stdio.h> #include <stdbool.h> #include <sys/socket.h> #include <sys/types.h> #include <netinet/in.h> #include <arpa/inet.h> #include <unistd.h> #include <ctype.h> #include <strings.h> #include <string.h> #include <sys/stat.h> #include <pthread.h> #include <sys/wait.h> #include <stdlib.h> #include <errno.h> #include <signal.h> #include <stdatomic.h> #include <sys/wait.h> /**************************************************************************************************/ /* DEFINES */ /**************************************************************************************************/ #define ISspace(x) isspace((int)(x)) #define SERVER_STRING "Server: jdbhttpd/0.1.0\r\n" #define MAX_PROCESSES 100 // 最大子进程数量限制 #define DOCUMENT_ROOT "htdocs" /**************************************************************************************************/ /* LOCAL_PROTOTYPES */ /**************************************************************************************************/ void accept_request(int client_sock); void bad_request(int client); void cat(int, FILE *); void cannot_execute(int); void error_die(const char *); void execute_cgi(int, const char *, const char *, const char *); int get_line(int, char *, int); void headers(int, const char *); void not_found(int); void serve_file(int, const char *); int startup(u_short *); void unimplemented(int); void normalize_path(char *path); const char *get_content_type(const char *path); void handle_sigpipe(int sig); /**************************************************************************************************/ /* LOCAL_FUNCTIONS */ /**************************************************************************************************/ /*! * @brief 路径规范函数 * * @param[in] path 文件路径 */ void normalize_path(char *path) { char *p = path; char *q = path; while (*p) { if (strncmp(p, "/../", 4) == 0) { p += 3; while (q > path && *--q != '/') { ; } } else if (strncmp(p, "/./", 3) == 0) { p += 2; } else if (strncmp(p, "//", 2) == 0) { p += 1; } else { *q++ = *p++; } } *q = '\0'; } /*! * @brief 忽略SIGPIPE信号处理 * * @param[in] sig SIGPIPE信号 */ void handle_sigpipe(int sig) { } /*! * @brief * * @param[in] ctx Comment */ void accept_request(int client_sock) { int client = client_sock; char buf[1024]; char method[255]; char url[255]; char path[512]; struct stat st; int cgi = 0; char *query_string = NULL; int numchars = get_line(client, buf, sizeof(buf)); size_t i = 0; size_t j = 0; while (!ISspace(buf[j]) && (i < sizeof(method) - 1)) { method[i] = buf[j]; i++; j++; } method[i] = '\0'; // 只支持GET和POST方法 if (strcasecmp(method, "GET") && strcasecmp(method, "POST")) { unimplemented(client); close(client); return; } // POST请求启用CGI if (strcasecmp(method, "POST") == 0) { cgi = 1; } i = 0; while (ISspace(buf[j]) && (j < sizeof(buf))) { j++; } while (!ISspace(buf[j]) && (i < sizeof(url) - 1) && (j < sizeof(buf))) { url[i] = buf[j]; i++; j++; } url[i] = '\0'; // 处理GET查询参数 if (strcasecmp(method, "GET") == 0) { query_string = url; while ((*query_string != '?') && (*query_string != '\0')) query_string++; if (*query_string == '?') { cgi = 1; *query_string = '\0'; query_string++; } } // 构建安全路径 if (strlen(url) == 0 || strstr(url, "..") != NULL) { bad_request(client); close(client); return; } snprintf(path, sizeof(path), "%s%s", DOCUMENT_ROOT, url); normalize_path(path); // 确保路径在文档根目录内 if (strncmp(path, DOCUMENT_ROOT, strlen(DOCUMENT_ROOT)) != 0) { not_found(client); close(client); return; } if (path[strlen(path) - 1] == '/') { strncat(path, "index.html", sizeof(path) - strlen(path) - 1); } if (stat(path, &st) == -1) { while ((numchars > 0) && strcmp("\n", buf) != 0) { numchars = get_line(client, buf, sizeof(buf)); } not_found(client); } else { if (S_ISDIR(st.st_mode)) { strncat(path, "/index.html", sizeof(path) - strlen(path) - 1); stat(path, &st); } if ((st.st_mode & S_IXUSR) || (st.st_mode & S_IXGRP) || (st.st_mode & S_IXOTH)) { cgi = 1; } if (!cgi) { serve_file(client, path); } else { execute_cgi(client, path, method, query_string); } } /* 清理资源 */ close(client); } /**********************************************************************/ /* Inform the client that a request it has made has a problem. * Parameters: client socket */ /**********************************************************************/ void bad_request(int client) { char buf[1024]; sprintf(buf, "HTTP/1.0 400 BAD REQUEST\r\n"); send(client, buf, sizeof(buf), 0); sprintf(buf, "Content-type: text/html\r\n"); send(client, buf, sizeof(buf), 0); sprintf(buf, "\r\n"); send(client, buf, sizeof(buf), 0); sprintf(buf, "<P>Your browser sent a bad request, "); send(client, buf, sizeof(buf), 0); sprintf(buf, "such as a POST without a Content-Length.\r\n"); send(client, buf, sizeof(buf), 0); } /*! * @brief 将文件内容发送到网络客户端 * * @param[in] client 客户端套接字描述符 * @param[in] resource 文件指针(指向要发送的文件) */ void cat(int client, FILE *resource) { char buf[1024]; size_t bytes_read; while ((bytes_read = fread(buf, 1, sizeof(buf), resource)) > 0) { if (send(client, buf, bytes_read, 0) < bytes_read) { perror("send"); break; } } } /**********************************************************************/ /* Inform the client that a CGI script could not be executed. * Parameter: the client socket descriptor. */ /**********************************************************************/ void cannot_execute(int client) { char buf[1024]; sprintf(buf, "HTTP/1.0 500 Internal Server Error\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "Content-type: text/html\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "<P>Error prohibited CGI execution.\r\n"); send(client, buf, strlen(buf), 0); } /**********************************************************************/ /* Print out an error message with perror() (for system errors; based * on value of errno, which indicates system call errors) and exit the * program indicating an error. */ /**********************************************************************/ void error_die(const char *sc) { perror(sc); exit(1); } /**********************************************************************/ /* Execute a CGI script. Will need to set environment variables as * appropriate. * Parameters: client socket descriptor * path to the CGI script */ /**********************************************************************/ void execute_cgi(int client, const char *path, const char *method, const char *query_string) { // 缓冲区 char buf[1024]; int cgi_output[2]; int cgi_input[2]; pid_t pid; int status; int i = 0; char c; int numchars = 1; int content_length = -1; // 默认字符 buf[0] = 'A'; buf[1] = '\0'; // 忽略大小写比较字符串 if (strcasecmp(method, "GET") == 0) { while ((numchars > 0) && strcmp("\n", buf)) /* read & discard headers */ { numchars = get_line(client, buf, sizeof(buf)); } } else /* POST */ { numchars = get_line(client, buf, sizeof(buf)); while ((numchars > 0) && strcmp("\n", buf)) { buf[15] = '\0'; if (strcasecmp(buf, "Content-Length:") == 0) { content_length = atoi(&(buf[16])); } numchars = get_line(client, buf, sizeof(buf)); } if (content_length == -1) { bad_request(client); return; } } sprintf(buf, "HTTP/1.0 200 OK\r\n"); send(client, buf, strlen(buf), 0); /* 建立output管道 */ if (pipe(cgi_output) < 0) { cannot_execute(client); return; } /* 建立input管道 */ if (pipe(cgi_input) < 0) { cannot_execute(client); return; } if ((pid = fork()) < 0) { cannot_execute(client); return; } if (pid == 0) /* child: CGI script */ { char meth_env[255]; char query_env[255]; char length_env[255]; // 子进程输出重定向到output管道的1端 dup2(cgi_output[1], 1); // 子进程输入重定向到input管道的0端 dup2(cgi_input[0], 0); // 关闭无用管道口 close(cgi_output[0]); close(cgi_input[1]); // CGI环境变量 sprintf(meth_env, "REQUEST_METHOD=%s", method); putenv(meth_env); if (strcasecmp(method, "GET") == 0) { sprintf(query_env, "QUERY_STRING=%s", query_string); putenv(query_env); } else { /* POST */ sprintf(length_env, "CONTENT_LENGTH=%d", content_length); putenv(length_env); } // 替换执行path execl(path, path, NULL); // int m = execl(path, path, NULL); // 如果path有问题,例如将html网页改成可执行的,但是执行后m为-1 // 退出子进程,管道被破坏,但是父进程还在往里面写东西,触发Program received signal SIGPIPE, Broken pipe. exit(0); } else { /* parent */ close(cgi_output[1]); close(cgi_input[0]); if (strcasecmp(method, "POST") == 0) { for (i = 0; i < content_length; i++) { recv(client, &c, 1, 0); ssize_t bytes_written = write(cgi_input[1], &c, 1); if (bytes_written <= 0) { perror("Failed to write to CGI"); close(cgi_input[1]); close(cgi_input[0]); break; } } } while (read(cgi_output[0], &c, 1) > 0) { send(client, &c, 1, 0); } close(cgi_output[0]); close(cgi_input[1]); waitpid(pid, &status, 0); } } /**********************************************************************/ /* Get a line from a socket, whether the line ends in a newline, * carriage return, or a CRLF combination. Terminates the string read * with a null character. If no newline indicator is found before the * end of the buffer, the string is terminated with a null. If any of * the above three line terminators is read, the last character of the * string will be a linefeed and the string will be terminated with a * null character. * Parameters: the socket descriptor * the buffer to save the data in * the size of the buffer * Returns: the number of bytes stored (excluding null) */ /**********************************************************************/ // 得到一行数据,只要发现c为\n,就认为是一行结束,如果读到\r,再用MSG_PEEK的方式读入一个字符,如果是\n,从socket用读出 // 如果是下个字符则不处理,将c置为\n,结束。如果读到的数据为0中断,或者小于0,也视为结束,c置为\n /*! * @brief 从socket中获取一行数据 * * @param[in] sock socket * @param[in] buf 用于保存数据的缓冲区 * @param[in] size 缓冲区的大小 * @return int 存储的字节数 */ int get_line(int sock, char *buf, int size) { int i = 0; char c = '\0'; int n; while ((i < size - 1) && (c != '\n')) { n = recv(sock, &c, 1, 0); if (n > 0) { if (c == '\r') { n = recv(sock, &c, 1, MSG_PEEK); if ((n > 0) && (c == '\n')) { recv(sock, &c, 1, 0); } else { c = '\n'; } } buf[i] = c; i++; } else c = '\n'; } buf[i] = '\0'; return (i); } /*! * @brief 根据文件路径的扩展名返回对应的 MIME 类型 * * @param[in] path 路径字符串 * @return const char* */ const char *get_content_type(const char *path) { const char *ext = strrchr(path, '.'); if (ext) { if (strcasecmp(ext, ".css") == 0) { return "text/css"; } if (strcasecmp(ext, ".js") == 0) { return "application/javascript"; } if (strcasecmp(ext, ".png") == 0) { return "image/png"; } if (strcasecmp(ext, ".jpg") == 0 || strcasecmp(ext, ".jpeg") == 0) { return "image/jpeg"; } if (strcasecmp(ext, ".gif") == 0) { return "image/gif"; } if (strcasecmp(ext, ".ico") == 0) { return "image/x-icon"; } if (strcasecmp(ext, ".svg") == 0) { return "image/svg+xml"; } if (strcasecmp(ext, ".woff") == 0) { return "font/woff"; } if (strcasecmp(ext, ".woff2") == 0) { return "font/woff2"; } } return "text/html"; } /*! * @brief 发送HTTP响应头 * * @param[in] client 客户端 * @param[in] filename 文件名 */ void headers(int client, const char *filename) { char buf[1024]; const char *content_type = get_content_type(filename); sprintf(buf, "HTTP/1.0 200 OK\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, SERVER_STRING); send(client, buf, strlen(buf), 0); sprintf(buf, "Content-Type: %s\r\n", content_type); send(client, buf, strlen(buf), 0); sprintf(buf, "\r\n"); send(client, buf, strlen(buf), 0); } /*! * @brief 404 * * @param[in] client 客户端 */ void not_found(int client) { char buf[1024]; sprintf(buf, "HTTP/1.0 404 NOT FOUND\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, SERVER_STRING); send(client, buf, strlen(buf), 0); sprintf(buf, "Content-Type: text/html\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "<HTML><TITLE>Not Found</TITLE>\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "<BODY><P>The server could not fulfill\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "your request because the resource specified\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "is unavailable or nonexistent.\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "</BODY></HTML>\r\n"); send(client, buf, strlen(buf), 0); } /*! * @brief 如果不是CGI文件,直接读取文件返回给请求的http客户端 * * @param[in] client 客户端 * @param[in] filename 文件名 */ void serve_file(int client, const char *filename) { FILE *resource = NULL; int numchars = 1; char buf[1024]; buf[0] = 'A'; buf[1] = '\0'; while ((numchars > 0) && strcmp("\n", buf)) { numchars = get_line(client, buf, sizeof(buf)); } resource = fopen(filename, "rb"); if (resource == NULL) { not_found(client); } else { headers(client, filename); cat(client, resource); } fclose(resource); } /**********************************************************************/ /* This function starts the process of listening for web connections * on a specified port. If the port is 0, then dynamically allocate a * port and modify the original port variable to reflect the actual * port. * Parameters: pointer to variable containing the port to connect on * Returns: the socket */ /**********************************************************************/ int startup(u_short *port) { int httpd = 0; struct sockaddr_in name; httpd = socket(PF_INET, SOCK_STREAM, 0); if (httpd == -1) { error_die("socket"); } memset(&name, 0, sizeof(name)); name.sin_family = AF_INET; name.sin_port = htons(*port); name.sin_addr.s_addr = htonl(INADDR_ANY); if (bind(httpd, (struct sockaddr *)&name, sizeof(name)) < 0) { error_die("bind"); } if (*port == 0) { socklen_t namelen = sizeof(name); if (getsockname(httpd, (struct sockaddr *)&name, &namelen) == -1) { error_die("getsockname"); } *port = ntohs(name.sin_port); } if (listen(httpd, 5) < 0) { error_die("listen"); } return (httpd); } /*! * @brief 没有实现请求 * * @param[in] client 客户端 */ void unimplemented(int client) { char buf[1024]; sprintf(buf, "HTTP/1.0 501 Method Not Implemented\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, SERVER_STRING); send(client, buf, strlen(buf), 0); sprintf(buf, "Content-Type: text/html\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "<HTML><HEAD><TITLE>Method Not Implemented\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "</TITLE></HEAD>\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "<BODY><P>HTTP request method not supported.\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "</BODY></HTML>\r\n"); send(client, buf, strlen(buf), 0); } int main(void) { int server_sock = -1; u_short port = 80; // 使用8080端口避免权限问题 struct sockaddr_in client_name; socklen_t client_name_len = sizeof(client_name); // 设置信号处理 signal(SIGPIPE, handle_sigpipe); server_sock = startup(&port); printf("HTTP server running on port %d\n", port); while (1) { int client_sock = accept(server_sock, (struct sockaddr *)&client_name, &client_name_len); if (client_sock == -1) { perror("accept failed"); continue; } pid_t pid = fork(); if (pid < 0) { perror("fork failed"); close(client_sock); } else if (0 == pid) { close(server_sock); accept_request(client_sock); exit(EXIT_SUCCESS); } else { close(client_sock); } } close(server_sock); return 0; } 实现以IO多路复用方式实现web server功能(必修) 要求尽可能少的修改代码,并列出要添加或者删除的部分
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