Linux查找某一进程的PID（c语言）

目的：要在程序中检查某一个程序是否执行完毕，所以需要检测这个程序是否在运行状态.

#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 ;
}