Linux下C/C++查找某一进程
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 stdio.h>#include unistd.h>#include string.h>#include signal.h>int main()
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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 < stdio.h > #include < unistd.h > #include < string .h > #include < signal.h > 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 < unistd.h > #include < dirent.h > #include < sys / types.h > // for opendir(), readdir(), closedir() #include < sys / stat.h > // for stat() #ifdef __cplusplus #include < iostream > #include < cstdlib > #include < cstring > #include < cstdarg > #else #include < stdio.h > #include < stdlib.h > #include < string .h > #include < stdarg.h > #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/<NR>/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 < unistd.h > #include < dirent.h > #include < sys / types.h > // for opendir(), readdir(), closedir() #include < sys / stat.h > // for stat() #include < stdio.h > #include < stdlib.h > #include < string .h > #include < stdarg.h > #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/<NR>/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 ; }
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