管道
#include <stdio.h>
FILE *popen(const char *command,const char *open_mode);
int pclose(FILE *stream_to_close);
代码
#include
<
unistd.h
>
#include
<
stdio.h
>
#include
<
stdlib.h
>
#include
<
string
.h
>
int
main(
void
)
{
FILE
*
write_fp;
char
buffer[BUFSIZ
+
1
];
sprintf(buffer,
"
Once upon a time,there was...\n
"
);
write_fp
=
popen(
"
od -c
"
,
"
w
"
);
if
(write_fp
!=
NULL)
{
fwrite(buffer,
sizeof
(
char
),strlen(buffer),write_fp);
pclose(write_fp);
}
return
0
;
}
代码
#include
<
unistd.h
>
#include
<
stdio.h
>
#include
<
stdlib.h
>
#include
<
string
.h
>
int
main()
{
FILE
*
read_fp;
char
buffer[BUFSIZ
+
1
];
int
chars_read;
memset(buffer,
'
\0
'
,
sizeof
(buffer));
read_fp
=
popen(
"
ps -ax
"
,
"
r
"
);
if
(read_fp
!=
NULL)
{
chars_read
=
fread(buffer,
sizeof
(
char
),BUFSIZ,read_fp);
while
(chars_read
>
0
)
{
buffer[chars_read
-
1
]
=
'
\0
'
;
printf(
"
Reading:-\n%s\n
"
,buffer);
chars_read
=
fread(buffer,
sizeof
(
char
),BUFSIZ,read_fp);
}
}
pclose(read_fp);
return
0
;
}
读取大量数据：
代码
#include
<
unistd.h
>
#include
<
stdio.h
>
#include
<
stdlib.h
>
#include
<
string
.h
>
int
main(
void
)
{
FILE
*
fread_fp;
char
buffer[BUFSIZ
+
1
];
int
chars_bytes;
fread_fp
=
popen(
"
cat popen*.c | wc -l
"
,
"
r
"
);
if
(fread_fp
!=
NULL)
{
chars_bytes
=
fread(buffer,
sizeof
(
char
),BUFSIZ,fread_fp);
while
(chars_bytes
>
0
)
{
buffer[chars_bytes
-
1
]
=
'
\0
'
;
printf(
"
\n%s\n
"
,buffer);
chars_bytes
=
fread(buffer,
sizeof
(
char
),BUFSIZ,fread_fp);
}
pclose(fread_fp);
}
return
0
;
}
#include <unistd.h>
int pipe(int file_descripter[2]);
基本使用:
代码
#include
<
unistd.h
>
#include
<
stdlib.h
>
#include
<
stdio.h
>
#include
<
string
.h
>
int
main(
void
)
{
int
data_processed;
int
file_pipes[
2
];
const
char
some_data[]
=
"
123
"
;
char
buffer[BUFSIZ
+
1
];
memset(buffer,
'
\0
'
,
sizeof
(buffer));
if
(pipe(file_pipes)
==
0
)
{
data_processed
=
write(file_pipes[
1
],some_data,strlen(some_data));
printf(
"
wrote %d bytes\n
"
,data_processed);
data_processed
=
read(file_pipes[
0
],buffer,BUFSIZ);
printf(
"
read %d bytes:%s\n
"
,data_processed,buffer);
}
return
0
;
}
利用fork调用管道:
代码
#include
<
unistd.h
>
#include
<
stdio.h
>
#include
<
stdlib.h
>
#include
<
string
.h
>
int
main(
void
)
{
int
file_pipes[
2
];
int
data_processed;
const
char
some_data[]
=
"
1234
"
;
char
buffer[BUFSIZ
+
1
];
pid_t fork_result;
memset(buffer,
'
\0
'
,
sizeof
(buffer));
if
(pipe(file_pipes)
==
0
)
{
fork_result
=
fork();
if
(fork_result
==-
1
)
{
fprintf(stderr,
"
Fork failure
"
);
return
1
;
}
if
(fork_result
==
0
)
{
data_processed
=
read(file_pipes[
0
],buffer,BUFSIZ);
printf(
"
read %d bytes:%s\n
"
,data_processed,buffer);
return
1
;
}
else
{
data_processed
=
write(file_pipes[
1
],some_data,strlen(some_data));
printf(
"
write %d bytes\n
"
,data_processed);
}
}
return
0
;
}