使用select（）和read（）; [英] Using select() and read();

问题描述

嘿所有..

我在我的程序中遇到了一些问题，我在c中写了linux。我用
使用select（）来监控用户是否按下了一个键，然后用read（）读取键

。它在我的IBM笔记本电脑上工作得很好，但是一旦我将程序移动到我的戴尔笔记本电脑上，好像它甚至不能识别选择功能。

那是，它根本不使用分配的超时。当我在任何一台计算机上编译时，我都没有收到任何错误

。我在两台笔记本电脑上运行debian /测试和

i使用CVS进行版本控制..我试图在IBM上编译它并且

在dell上运行它..但似乎没什么用。


- 马丁


代码是这样的：


#include< sys / types.h>

#include< sys / stat.h>

#include< asm / io.h>

#include< fcntl.h>

#include< termios.h>

#include< stdio.h>

#include< string.h>

#include< stdlib.h>

#include< unistd.h>

#include< limits.h>

#include< time.h>

#include< termio.h>

#include< sys / ioctl.h>


struct termio OldTerm;

struct termio NewTerm;

struct timeval tv1;


void SetRaw（int）;

void TermRestore（int）;


int main（void ）{

int fd = 0，r es = 0，i = 0;

char keystroke = 0;

fd_set rfds1;


SetRaw（fd）;

FD_ZERO（& rfds1）;

FD_SET（fileno（stdin），& rfds1）;

while（1）{


tv1.tv_sec = 0;

tv1.tv_usec = 1;


/ *打印菜单* /

res = select（fd + 1，& rfds1，NULL，NULL，& tv1）;

if（res）{

read（ fd，& keystroke，1）;


if（keystroke ==''1'）{


}


if（keystroke ==''2''）{


}


if（keystroke == ''3''）{


}


if（keystroke ==''0''）{

printf（" s？ slutter vi！\ n"）;

TermRestore（fd）;

退出（1）;

}

}

系统（清除）;

}


TermRestore（fd）;

返回0;

}


无效SetRaw（int fd）

{


/ *

*获取终端模式，并将它们保存在OldTerm结构中。

* /

（void）ioctl（ fd，TCGETA，& OldTerm）;

/ *

*将模式设置为我们想要的模式。

* /

NewTerm.c_lflag& =〜（ICANON | ECHO | ECHOE | ECHOK | ECHONL）;

NewTerm.c_oflag | =（OPOST | ONLCR | TAB3）;

NewTerm.c_oflag& =〜（OCRNL | ONOCR | ONLRET）;

NewTerm.c_cc [VMIN] = 1;

NewTerm.c_cc [VTIME] = 0;

（无效）ioctl（fd，TCSETAW，& NewTerm）;

printf（" fd is％d \ n"，fd）; < br $>
}


无效TermRestore（int fd）

{

/ *

*恢复保存的模式。

* /

（void）ioctl（fd，TCSETAW，& OldTerm）;

}

解决方案

On Thu ，2004年5月13日11:40:55 +0200，Martin Holm Pedersen写道：


您好这可能不是comp.lang.c的主题，但是对于

comp.unix.programmer。交叉链接和后续设置。

嘿所有..
我的程序有点问题，我在c中为linux写的。我使用select（）来监视用户是否按下了一个键并使用read（）读取了该键。它在我的IBM笔记本电脑上运行良好，但是一旦我将程序移动到我的戴尔笔记本电脑上，它似乎甚至都不能识别选择功能。
也就是说，它没有使用完全分配超时。当我在任何一台计算机上编译时，我都没有收到任何错误。我在两台笔记本电脑上运行debian /测试和
我使用CVS进行版本控制..我试图在IBM上编译它并在戴尔上运行它..但似乎没有任何工作..

- 马丁

代码是这样的：

#include< sys / types.h>
＃ include< sys / stat.h>
#include< asm / io.h>
#include< fcntl.h>
#include< termios.h>
#include< stdio.h>
#include< string.h>
#include< stdlib.h>
#include< unistd.h>
＃ include< limits.h>
#include< time.h>
#include< termio.h>
#include< sys / ioctl.h>

struct termio OldTerm;
struct termio NewTerm;
struct timeval tv1;

void SetRaw（int）;
void TermRestore（int）;

int main（void）{
int fd = 0，res = 0，i = 0;
char keystroke = 0;
fd_set rfds1;

SetRaw（fd）;
FD_ZERO（& rfds1）;
FD_SET（fileno（stdin），& rfds1）;
while（1）{

tv1.tv_sec = 0;
tv1.tv_usec = 1;

/ *打印菜单* /
res =选择（fd + 1，& rfds1，NULL，NULL和& tv1）;
if（res）{
read（ fd，& keystroke，1）;

if（keystroke ==''1'）{

}

if（keystroke = ='''''）{

}
如果（击键==''3''）{

}

if（keystroke ==''0''）{
printf（" s？ slutter vi！\\\
"）;
TermRestore（fd）;
exit（1）;
}
}
system（clear）; <

TermRestore（fd）;
返回0;
}

void SetRaw（int fd）
{

/ *
*获取终端模式，并将它们保存在OldTerm结构中。
* /
（void）ioctl（fd，TCGETA，& OldTerm）;


查看退货价格


/ *
*将模式设置为我们想要的模式。
* /
NewTerm.c_lflag& =〜（ICANON | ECHO | ECHOE | ECHOK | ECHONL）;
NewTerm.c_oflag | =（OPOST | ONLCR | TAB3）;
NewTerm.c_oflag& = 〜（OCRNL | ONOCR | ONLRET）;
NewTerm.c_cc [VMIN] = 1;
NewTerm.c_cc [VTIME] = 0;
（void）ioctl（fd，TCSETAW，& NewTerm）;


查看返回值

printf（fd is％d \ nn，fd）;
}

void TermRestore（int fd）
{
/ *
*恢复保存的模式。
* /
（void）ioctl（fd，TCSETAW，& OldTerm ）;


查看返回值

}

-

NPV


大字打印，小字打印

Tom Waits - 向上走吧

Martin Holm Pedersen< mh **** @ kom.auc.dk>写道：

struct termio OldTerm;
struct termio NewTerm;


....

无效SetRaw（int fd）
{

/ *
*获取终端模式，并将它们保存在OldTerm结构中。
* /
（void）ioctl（fd，TCGETA，& OldTerm）;


你也想要将NewTerm初始化...... :-)

/ *
*将模式设置为我们想要的方式他们。
* /
NewTerm.c_lflag& =〜（ICANON | ECHO | ECHOE | ECHOK | ECHONL）;
NewTerm.c_oflag | =（OPOST | ONLCR | TAB3）;
NewTerm.c_cc [VMIN] = 1;
NewTerm.c_cc [VTIME] = 0;
（void） ioctl（fd，TCSETAW，& NewTerm）;


如果它在这一点上做任何事情都是意外的！

printf（fd is％d \ nn，fd）;
}

void TermRestore（int fd）
{
/ *
*恢复已保存的模式。
* /
（ void）ioctl（fd，TCSETAW，& OldTerm）;
}

-

Floyd L. Davidson< http://web.newsguy.com/floyd_davidson>

Ukpeagvik（阿拉斯加州巴罗市） fl *** @ barrow。 com

Floyd L. Davidson写道：

Martin Holm Pedersen< mh **** @ kom .auc.dk>写道：

struct termio OldTerm;
struct termio NewTerm;
...

void SetRaw（int fd ）
{

/ *
*获取终端模式，并将它们保存在OldTerm结构中。
* /
（void）ioctl（fd， TCGETA，& OldTerm）;

你也想要将NewTerm初始化......： - ）

（void）ioctl（fd，TCGETA，& OldTerm）;

用于获取现有设置并将其保存在OldTerm中？


我必须初始化NewTerm超过：

struct termio NewTerm; ??

/ *
*将模式设置为我们想要的模式。
* /
NewTerm.c_lflag& =〜（ICANON | ECHO | ECHOE | ECHOK | ECHONL）;
NewTerm.c_oflag | =（OPOST | ONLCR | TAB3）;
NewTerm.c_oflag& =〜（OCRNL | ONOCR | ONLRET）;
NewTerm.c_cc [VMIN] = 1;
NewTerm.c_cc [VTIME] = 0;
（void）ioctl（fd，TCSETAW，& NewTerm）;

printf（fd is％d \ nn，fd）;
}

void TermRestore（int fd）
{
/ *
*恢复保存的模式。
* /
（void）ioctl（fd， TCSETAW，& OldTerm）;
}

- Floyd L. Davidson< http://web.newsguy.com/floyd_davidson>
fl***@barrow.com

Hey All..
Im having a bit of a problem with my program that i wrote for linux in c. I
use select() to monitor if the user has pressed a key and reads the key
with read(). It works fine om my IBM laptop but once i move the program to
my dell laptop it seems like it doesn''t even recognize the select-function.
That is, it doesn''t use the timeout assigned at all. I don''t get any errors
when i compile on either computer. I run debian/testing on both laptops and
i use CVS for version-control.. I have tried to compile it on the IBM and
run it on the dell.. But nothing seems to work..

- Martin

The code is something along the lines of:

#include <sys/types.h>
#include <sys/stat.h>
#include <asm/io.h>
#include <fcntl.h>
#include <termios.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <limits.h>
#include <time.h>
#include <termio.h>
#include <sys/ioctl.h>

struct termio OldTerm;
struct termio NewTerm;
struct timeval tv1;

void SetRaw(int);
void TermRestore(int);

int main(void) {
int fd=0, res=0, i=0;
char keystroke = 0;
fd_set rfds1;

SetRaw(fd);
FD_ZERO(&rfds1);
FD_SET(fileno(stdin), &rfds1);
while(1){

tv1.tv_sec=0;
tv1.tv_usec=1;

/* PRINT THE MENU */
res=select(fd+1, &rfds1,NULL,NULL,&tv1);
if(res){
read(fd, &keystroke, 1);

if(keystroke==''1''){

}

if(keystroke==''2''){

}

if(keystroke==''3''){

}

if(keystroke==''0''){
printf("s? slutter vi!\n");
TermRestore(fd);
exit(1);
}
}
system("clear");
}

TermRestore(fd);
return 0;
}

void SetRaw(int fd)
{

/*
* Get terminal modes, and saves them in the OldTerm struct.
*/
(void)ioctl(fd, TCGETA, &OldTerm);
/*
* Set the modes to the way we want them.
*/
NewTerm.c_lflag &= ~(ICANON|ECHO|ECHOE|ECHOK|ECHONL);
NewTerm.c_oflag |= (OPOST|ONLCR|TAB3);
NewTerm.c_oflag &= ~(OCRNL|ONOCR|ONLRET);
NewTerm.c_cc[VMIN] = 1;
NewTerm.c_cc[VTIME] = 0;
(void)ioctl(fd, TCSETAW, &NewTerm);
printf("fd is %d\n", fd);
}

void TermRestore(int fd)
{
/*
* Restore saved modes.
*/
(void)ioctl(fd, TCSETAW, &OldTerm);
}

解决方案

On Thu, 13 May 2004 11:40:55 +0200, Martin Holm Pedersen wrote:

Hi This is probably not a topic for comp.lang.c but for
comp.unix.programmer. Crossposted and followups set.

Hey All..
Im having a bit of a problem with my program that i wrote for linux in c. I
use select() to monitor if the user has pressed a key and reads the key
with read(). It works fine om my IBM laptop but once i move the program to
my dell laptop it seems like it doesn''t even recognize the select-function.
That is, it doesn''t use the timeout assigned at all. I don''t get any errors
when i compile on either computer. I run debian/testing on both laptops and
i use CVS for version-control.. I have tried to compile it on the IBM and
run it on the dell.. But nothing seems to work..

- Martin

The code is something along the lines of:

#include <sys/types.h>
#include <sys/stat.h>
#include <asm/io.h>
#include <fcntl.h>
#include <termios.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <limits.h>
#include <time.h>
#include <termio.h>
#include <sys/ioctl.h>

struct termio OldTerm;
struct termio NewTerm;
struct timeval tv1;

void SetRaw(int);
void TermRestore(int);

int main(void) {
int fd=0, res=0, i=0;
char keystroke = 0;
fd_set rfds1;

SetRaw(fd);
FD_ZERO(&rfds1);
FD_SET(fileno(stdin), &rfds1);
while(1){

tv1.tv_sec=0;
tv1.tv_usec=1;

/* PRINT THE MENU */
res=select(fd+1, &rfds1,NULL,NULL,&tv1);
if(res){
read(fd, &keystroke, 1);

if(keystroke==''1''){

}

if(keystroke==''2''){

}

if(keystroke==''3''){

}

if(keystroke==''0''){
printf("s? slutter vi!\n");
TermRestore(fd);
exit(1);
}
}
system("clear");
}

TermRestore(fd);
return 0;
}

void SetRaw(int fd)
{

/*
* Get terminal modes, and saves them in the OldTerm struct.
*/
(void)ioctl(fd, TCGETA, &OldTerm);
Check return value


/*
* Set the modes to the way we want them.
*/
NewTerm.c_lflag &= ~(ICANON|ECHO|ECHOE|ECHOK|ECHONL);
NewTerm.c_oflag |= (OPOST|ONLCR|TAB3);
NewTerm.c_oflag &= ~(OCRNL|ONOCR|ONLRET);
NewTerm.c_cc[VMIN] = 1;
NewTerm.c_cc[VTIME] = 0;
(void)ioctl(fd, TCSETAW, &NewTerm);
Check return value
printf("fd is %d\n", fd);
}

void TermRestore(int fd)
{
/*
* Restore saved modes.
*/
(void)ioctl(fd, TCSETAW, &OldTerm);
Check return value
}

--
NPV

"the large print giveth, and the small print taketh away"
Tom Waits - Step right up

Martin Holm Pedersen <mh****@kom.auc.dk> wrote:

struct termio OldTerm;
struct termio NewTerm;
....
void SetRaw(int fd)
{

/*
* Get terminal modes, and saves them in the OldTerm struct.
*/
(void)ioctl(fd, TCGETA, &OldTerm);
You''ll want to initalize NewTerm also... :-)
/*
* Set the modes to the way we want them.
*/
NewTerm.c_lflag &= ~(ICANON|ECHO|ECHOE|ECHOK|ECHONL);
NewTerm.c_oflag |= (OPOST|ONLCR|TAB3);
NewTerm.c_oflag &= ~(OCRNL|ONOCR|ONLRET);
NewTerm.c_cc[VMIN] = 1;
NewTerm.c_cc[VTIME] = 0;
(void)ioctl(fd, TCSETAW, &NewTerm);
It''s an accident if it does anything at this point!
printf("fd is %d\n", fd);
}

void TermRestore(int fd)
{
/*
* Restore saved modes.
*/
(void)ioctl(fd, TCSETAW, &OldTerm);
}

--
Floyd L. Davidson <http://web.newsguy.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) fl***@barrow.com

Floyd L. Davidson wrote:

Martin Holm Pedersen <mh****@kom.auc.dk> wrote:

struct termio OldTerm;
struct termio NewTerm;
...

void SetRaw(int fd)
{

/*
* Get terminal modes, and saves them in the OldTerm struct.
*/
(void)ioctl(fd, TCGETA, &OldTerm);

You''ll want to initalize NewTerm also... :-)

(void)ioctl(fd, TCGETA, &OldTerm);
is for getting the existing settings and saving them in OldTerm?

Do i have to initialize NewTerm more than:
struct termio NewTerm; ??

/*
* Set the modes to the way we want them.
*/
NewTerm.c_lflag &= ~(ICANON|ECHO|ECHOE|ECHOK|ECHONL);
NewTerm.c_oflag |= (OPOST|ONLCR|TAB3);
NewTerm.c_oflag &= ~(OCRNL|ONOCR|ONLRET);
NewTerm.c_cc[VMIN] = 1;
NewTerm.c_cc[VTIME] = 0;
(void)ioctl(fd, TCSETAW, &NewTerm);

It''s an accident if it does anything at this point!

printf("fd is %d\n", fd);
}

void TermRestore(int fd)
{
/*
* Restore saved modes.
*/
(void)ioctl(fd, TCSETAW, &OldTerm);
}

--
Floyd L. Davidson <http://web.newsguy.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) fl***@barrow.com

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