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()
{
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 ;
}