进程和程序
execvp(const char *file,const char *argv);
代码
1
#include
<
unistd.h
>
2
#include
<
string
.h
>
3
#include
<
signal.h
>
4
#include
<
stdio.h
>
5
#include
<
stdlib.h
>
6
7
#define
MAXARGS 20
8
#define
ARGLEN 100
9
10
int
main(
void
)
11
{
12
char
*
arglist[MAXARGS
+
1
];
13
int
numargs;
14
char
argbuf[ARGLEN];
15
char
*
makestring();
16
17
numargs
=
0
;
18
19
while
(numargs
<
MAXARGS)
20
{
21
printf(
"
Arg[%d]:
"
,numargs);
22
if
(fgets(argbuf,ARGLEN,stdin)
&&
*
argbuf
!=
'
\n
'
)
23
arglist[numargs
++
]
=
makestring(argbuf);
24
else
25
{
26
if
(numargs
>
0
)
27
{
28
arglist[numargs]
=
NULL;
29
execute(arglist);
30
numargs
=
0
;
31
}
32
}
33
}
34
return
0
;
35
}
36
37
int
execute(
char
*
arglist[])
38
{
39
execvp(arglist[
0
],arglist);
40
perror(
"
execvp failed
"
);
41
exit(
1
);
42
}
43
44
char
*
makestring(
char
*
buf)
45
{
46
char
*
cp;
47
buf[strlen(buf)
-
1
]
=
'
\0
'
;
48
cp
=
(
char
*
)malloc(strlen(buf)
+
1
);
49
if
(cp
==
NULL)
50
{
51
fprintf(stderr,
"
no memory\n
"
);
52
exit(
1
);
53
}
54
strcpy(cp,buf);
55
return
cp;
56
}
57
pid_t result=fork(void);
代码
#include
<
unistd.h
>
#include
<
stdio.h
>
int
main(
void
)
{
int
ret_from_fork,mypid;
mypid
=
getpid();
printf(
"
Before:my pid is %d\n
"
,mypid);
ret_from_fork
=
fork();
sleep(
1
);
printf(
"
After my pid id %d,fork() said %d\n
"
,getpid(),ret_from_fork);
}
#include
<
unistd.h
>
#include
<
stdio.h
>
int
main(
void
)
{
printf(
"
my pid is %d\n
"
,getpid());
fork();
fork();
fork();
printf(
"
my pid is %d\n
"
,getpid());
}
代码
#include
<
unistd.h
>
#include
<
stdio.h
>
int
main(
void
)
{
int
fork_rv;
printf(
"
before %d\n
"
,getpid());
fork_rv
=
fork();
if
(fork_rv
==-
1
)
perror(
"
fork
"
);
else
if
(fork_rv
==
0
)
printf(
"
child:%d\n
"
,getpid());
else
printf(
"
parent:%d,my child is %d\n
"
,getpid(),fork_rv);
}
#include <sys/types.h>
#include <sys/wait.h>
pid_t result=wait(int *status);
代码
#include
<
unistd.h
>
#include
<
stdio.h
>
#include
<
stdlib.h
>
#define
DELAY 2
int
main(
void
)
{
int
newpid;
void
child_code(),parent_code();
printf(
"
before:my pid is %d\n
"
,getpid());
if
((newpid
=
fork())
==-
1
)
perror(
"
fork
"
);
else
if
(newpid
==
0
)
child_code(DELAY);
else
parent_code(newpid);
}
void
child_code(
int
delay)
{
printf(
"
child %d here,will sleep for %d seconds\n
"
,getpid(),delay);
sleep(delay);
printf(
"
child done about to exit\n
"
);
exit(
17
);
}
void
parent_code(
int
childpid)
{
int
wait_rv;
wait_rv
=
wait(NULL);
printf(
"
done waiting for %d,wait returned %d\n
"
,childpid,wait_rv);
}
代码
#include
<
stdlib.h
>
#include
<
unistd.h
>
#include
<
stdio.h
>
#define
DELAY 5
void
child_code();
void
parent_code();
int
main(
void
)
{
pid_t newpid;
printf(
"
before:my pid is %d\n
"
,getpid());
if
((newpid
=
fork())
==-
1
)
perror(
"
fork
"
);
else
if
(newpid
==
0
)
child_code(DELAY);
else
parent_code();
}
void
child_code(
int
delay)
{
printf(
"
child %d here will sleep for %d seconds\n
"
,getpid(),delay);
sleep(delay);
printf(
"
child done\n
"
);
exit(
17
);
}
void
parent_code(
int
childpid)
{
int
wait_rv;
int
child_status;
int
high_8,low_7,bit_7;
wait_rv
=
wait(
&
child_status);
printf(
"
done waiting for %d,wait return %d\n
"
,childpid,wait_rv);
high_8
=
child_status
>>
8
;
low_7
=
child_status
&
0x7F
;
bit_7
=
child_status
&
0x80
;
printf(
"
status:exit=%d,sig=%d,core=%d\n
"
,high_8,low_7,bit_7);
}
shell:
代码
#include
<
unistd.h
>
#include
<
stdlib.h
>
#include
<
string
.h
>
#include
<
stdio.h
>
#include
<
signal.h
>
#define
MAXARGS 20
#define
ARGLEN 100
char
*
makestring(
char
*
argbuf);
void
execute(
char
*
arglist[]);
int
main(
void
)
{
char
*
arglist[MAXARGS
+
1
];
int
numargs
=
0
;
char
argbuf[ARGLEN];
while
(numargs
<
MAXARGS)
{
printf(
"
Arg[%d]:
"
,numargs);
if
(fgets(argbuf,ARGLEN,stdin)
&&
*
argbuf
!=
'
\n
'
)
arglist[numargs
++
]
=
makestring(argbuf);
else
{
if
(numargs
>
0
)
{
arglist[numargs]
=
NULL;
execute(arglist);
numargs
=
0
;
}
}
}
return
0
;
}
char
*
makestring(
char
*
argbuf)
{
char
*
cp;
argbuf[strlen(argbuf)
-
1
]
=
'
\0
'
;
cp
=
(
char
*
)malloc(strlen(argbuf)
+
1
);
if
(cp
==
NULL)
{
fprintf(stderr,
"
no memory\n
"
);
exit(
1
);
}
strcpy(cp,argbuf);
return
cp;
}
void
execute(
char
*
arglist[])
{
int
pid,exitstatus;
pid
=
fork();
switch
(pid)
{
case
-
1
:
perror(
"
fork error
"
);
exit(
1
);
case
0
:
execvp(arglist[
0
],arglist);
perror(
"
execvp failed
"
);
exit(
1
);
default
:
while
(wait(
&
exitstatus)
!=
pid)
;
printf(
"
child exited with status %d,%d\n
"
,exitstatus
>>
8
,exitstatus
&
0377
);
}
}