linux下使用C或C++实现进程管理代码
一、前言：要在程序中启动某一程序，如果程序已经存在了，就不再启动。查找了N篇文档，有所收获，总结一下。
二、实现
大体分两种：
1、exec或popen执行ps的命令行，然后运用某几个字符串匹配函数。
#include#include #include <string.h> #include int main() { FILE *pstr; char cmd[128],buff[512],*p; pid_t pID; int pidnum; char *name= "ping ";//要查找的进程名 int ret=3; memset(cmd,0,sizeof(cmd)); sprintf(cmd, "ps -ef|grep %s ",name); pstr=popen(cmd, "r");// if(pstr==NULL) { return 1; } memset(buff,0,sizeof(buff)); fgets(buff,512,pstr); p=strtok(buff, " "); p=strtok(NULL, " "); //这句是否去掉，取决于当前系统中ps后，进程ID号是否是第一个字段 pclose(pstr); if(p==NULL) { return 1; } if(strlen(p)==0) { return 1; } if((pidnum=atoi(p))==0) { return 1; } printf("pidnum: %d\n",pidnum); pID=(pid_t)pidnum; ret=kill(pID,0);//这里不是要杀死进程，而是验证一下进程是否真的存在，返回0表示真的存在 printf("ret= %d \n",ret); if(0==ret) printf("process: %s exist!\n",name); else printf("process: %s not exist!\n",name); return 0; }
2、读取/proc文件
找到个代码如下：
读取/proc文件查找进程
#ifndef __cplusplus//识别C/C++的宏，望文生意 #define _GNU_SOURCE #endif #include#include #include // for opendir(), readdir(), closedir() #include // for stat() #ifdef __cplusplus #include #include #include #include #else #include #include #include <string.h> #include #endif #define PROC_DIRECTORY "/proc/" #define CASE_SENSITIVE 1 #define CASE_INSENSITIVE 0 #define EXACT_MATCH 1 #define INEXACT_MATCH 0 //是不是数字 int IsNumeric(const char* ccharptr_CharacterList) { for ( ; *ccharptr_CharacterList; ccharptr_CharacterList++) if (*ccharptr_CharacterList < '0' || *ccharptr_CharacterList > '9') return 0; // false return 1; // true } //intCaseSensitive=0大小写不敏感 int strcmp_Wrapper(const char *s1, const char *s2, int intCaseSensitive) { if (intCaseSensitive) return !strcmp(s1, s2); else return !strcasecmp(s1, s2); } //intCaseSensitive=0大小写不敏感 int strstr_Wrapper(const char* haystack, const char* needle, int intCaseSensitive) { if (intCaseSensitive) return (int) strstr(haystack, needle); else return (int) strcasestr(haystack, needle); } #ifdef __cplusplus pid_t GetPIDbyName(const char* cchrptr_ProcessName, int intCaseSensitiveness, int intExactMatch) #else pid_t GetPIDbyName_implements(const char* cchrptr_ProcessName, int intCaseSensitiveness, int intExactMatch) #endif { char chrarry_CommandLinePath[100] ; char chrarry_NameOfProcess[300] ; char* chrptr_StringToCompare = NULL ; pid_t pid_ProcessIdentifier = (pid_t) -1 ; struct dirent* de_DirEntity = NULL ; DIR* dir_proc = NULL ; int (*CompareFunction) (const char*, const char*, int) ; if (intExactMatch) CompareFunction = &strcmp_Wrapper; else CompareFunction = &strstr_Wrapper; dir_proc = opendir(PROC_DIRECTORY) ; if (dir_proc == NULL) { perror("Couldn't open the " PROC_DIRECTORY " directory") ; return (pid_t) -2 ; } // Loop while not NULL while ( (de_DirEntity = readdir(dir_proc)) ) { if (de_DirEntity->d_type == DT_DIR) { if (IsNumeric(de_DirEntity->d_name)) { strcpy(chrarry_CommandLinePath, PROC_DIRECTORY) ; strcat(chrarry_CommandLinePath, de_DirEntity->d_name) ; strcat(chrarry_CommandLinePath, "/cmdline") ; FILE* fd_CmdLineFile = fopen (chrarry_CommandLinePath, "rt") ; //open the file for reading text if (fd_CmdLineFile) { fscanf(fd_CmdLineFile, "%s", chrarry_NameOfProcess) ; //read from /proc/ /cmdline fclose(fd_CmdLineFile); //close the file prior to exiting the routine if (strrchr(chrarry_NameOfProcess, '/')) chrptr_StringToCompare = strrchr(chrarry_NameOfProcess, '/') +1 ; else chrptr_StringToCompare = chrarry_NameOfProcess ; //printf("Process name: %s\n", chrarry_NameOfProcess); //这个是全路径，比如/bin/ls //printf("Pure Process name: %s\n", chrptr_StringToCompare ); //这个是纯进程名，比如ls //这里可以比较全路径名，设置为chrarry_NameOfProcess即可 if ( CompareFunction(chrptr_StringToCompare, cchrptr_ProcessName, intCaseSensitiveness) ) { pid_ProcessIdentifier = (pid_t) atoi(de_DirEntity->d_name) ; closedir(dir_proc) ; return pid_ProcessIdentifier ; } } } } } closedir(dir_proc) ; return pid_ProcessIdentifier ; } #ifdef __cplusplus pid_t GetPIDbyName(const char* cchrptr_ProcessName) { return GetPIDbyName(cchrptr_ProcessName, CASE_INSENSITIVE, EXACT_MATCH) ; } #else // C cannot overload functions - fixed /*这里是原文的实现，但貌似需要某些牛X的设置，因不需要，删之 pid_t GetPIDbyName_Wrapper(const char* cchrptr_ProcessName, ... ) { int intTempArgument ; int intInputArguments[2] ; // intInputArguments[0] = 0 ; // intInputArguments[1] = 0 ; memset(intInputArguments, 0, sizeof(intInputArguments) ) ; int intInputIndex ; va_list argptr; va_start( argptr, cchrptr_ProcessName ); for (intInputIndex = 0; (intTempArgument = va_arg( argptr, int )) != 15; ++intInputIndex) { intInputArguments[intInputIndex] = intTempArgument ; } va_end( argptr ); return GetPIDbyName_implements(cchrptr_ProcessName, intInputArguments[0], intInputArguments[1]); } #define GetPIDbyName(ProcessName,...) GetPIDbyName_Wrapper(ProcessName, ##__VA_ARGS__, (int) 15) */ //简单实现 pid_t GetPIDbyName_Wrapper(const char* cchrptr_ProcessName) { return GetPIDbyName_implements(cchrptr_ProcessName, 0,0);//大小写不敏感 } #endif int main() { pid_t pid = GetPIDbyName_Wrapper("bash") ; // If -1 = not found, if -2 = proc fs access error printf("PID %d\n", pid); return EXIT_SUCCESS ; }
通过比较全路径，能一定程度上避免第1种方法的问题。
以下是整理后的C语言实现：
#include#include #include // for opendir(), readdir(), closedir() #include // for stat() #include #include #include <string.h> #include #define PROC_DIRECTORY "/proc/" #define CASE_SENSITIVE 1 #define CASE_INSENSITIVE 0 #define EXACT_MATCH 1 #define INEXACT_MATCH 0 //是不是数字 int IsNumeric(const char* ccharptr_CharacterList) { for ( ; *ccharptr_CharacterList; ccharptr_CharacterList++) if (*ccharptr_CharacterList < '0' || *ccharptr_CharacterList > '9') return 0; // false return 1; // true } //intCaseSensitive=0大小写不敏感 int strcmp_Wrapper(const char *s1, const char *s2, int intCaseSensitive) { if (intCaseSensitive) return !strcmp(s1, s2); else return !strcasecmp(s1, s2); } //intCaseSensitive=0大小写不敏感 int strstr_Wrapper(const char* haystack, const char* needle, int intCaseSensitive) { if (intCaseSensitive) return (int) strstr(haystack, needle); else return (int) strcasestr(haystack, needle); } pid_t GetPIDbyName_implements(const char* cchrptr_ProcessName, int intCaseSensitiveness, int intExactMatch) { char chrarry_CommandLinePath[100] ; char chrarry_NameOfProcess[300] ; char* chrptr_StringToCompare = NULL ; pid_t pid_ProcessIdentifier = (pid_t) -1 ; struct dirent* de_DirEntity = NULL ; DIR* dir_proc = NULL ; int (*CompareFunction) (const char*, const char*, int) ; if (intExactMatch) CompareFunction = &strcmp_Wrapper; else CompareFunction = &strstr_Wrapper; dir_proc = opendir(PROC_DIRECTORY) ; if (dir_proc == NULL) { perror("Couldn't open the " PROC_DIRECTORY " directory") ; return (pid_t) -2 ; } // Loop while not NULL while ( (de_DirEntity = readdir(dir_proc)) ) { if (de_DirEntity->d_type == DT_DIR) { if (IsNumeric(de_DirEntity->d_name)) { strcpy(chrarry_CommandLinePath, PROC_DIRECTORY) ; strcat(chrarry_CommandLinePath, de_DirEntity->d_name) ; strcat(chrarry_CommandLinePath, "/cmdline") ; FILE* fd_CmdLineFile = fopen (chrarry_CommandLinePath, "rt") ; //open the file for reading text if (fd_CmdLineFile) { fscanf(fd_CmdLineFile, "%s", chrarry_NameOfProcess) ; //read from /proc/ /cmdline fclose(fd_CmdLineFile); //close the file prior to exiting the routine if (strrchr(chrarry_NameOfProcess, '/')) chrptr_StringToCompare = strrchr(chrarry_NameOfProcess, '/') +1 ; else chrptr_StringToCompare = chrarry_NameOfProcess ; //printf("Process name: %s\n", chrarry_NameOfProcess); //这个是全路径，比如/bin/ls //printf("Pure Process name: %s\n", chrptr_StringToCompare ); //这个是纯进程名，比如ls //这里可以比较全路径名，设置为chrarry_NameOfProcess即可 if ( CompareFunction(chrptr_StringToCompare, cchrptr_ProcessName, intCaseSensitiveness) ) { pid_ProcessIdentifier = (pid_t) atoi(de_DirEntity->d_name) ; closedir(dir_proc) ; return pid_ProcessIdentifier ; } } } } } closedir(dir_proc) ; return pid_ProcessIdentifier ; } //简单实现 pid_t GetPIDbyName_Wrapper(const char* cchrptr_ProcessName) { return GetPIDbyName_implements(cchrptr_ProcessName, 0,0);//大小写不敏感 } int main() { pid_t pid = GetPIDbyName_Wrapper("bash") ; // If -1 = not found, if -2 = proc fs access error printf("PID %d\n", pid); return EXIT_SUCCESS ; }