无法写入pty-Linux [英] cannot write to pty - linux

问题描述

我是这样创建的pty设备的所有者权限是crw-w ----

  mknod pty1 c 1 1猫>pty1 

告诉我不允许进行操作.

稍后我要做的是，我使用open打开一个程序中的文件，然后调用write将输出发送到终端，就好像它是一个磁盘文件一样.

为什么猫不工作.我们可以写一个pty 还是从pty读，使用打开和写入.

我们可以从Java中做到这一点吗?java写入实际上是pty的文件.

问题的来源:强制程序在重定向时刷新其标准输出

更新:这个问题不清楚.我需要添加更多信息吗?

ls -la

的输出

  crw--w ---- 1个iamrohitbanga用户1，1 2010-01-13 18:27 pty1crw--w ---- 1 iamrohitbanga用户1，2 2010-01-13 18:29 pty2 

也

我什么时候做在一个终端中为cat/dev/pts/0，在另一个终端中为cat>/dev/pts/0，我看不到一个终端的输入被转移到另一终端.

解决方案

那不是PTY的工作方式；您应该阅读 man 4 pty 和 man 4点 .(不再使用旧的BSD风格的设备.)

为了打开伪终端从站(PTS)， posix_openpt(3) )，并使用 grantpt(3) 和 unlockpt(3) .

使用 forkpty(3)等.辅助函数比自己调用低级函数要容易得多.

即使在那之后，它也不像FIFO(您似乎期望的那样)那样工作:写入PTS的任何内容都会在PTM上出现，而从PTS读取的任何内容都是从PTM写入的.

i am the owner of the pty device created like this permissions are crw-w----

mknod pty1 c 1 1
cat > pty1

tells me operation not permitted.

what i want to do later is that i open the file from a program using open and call write to send output to the terminal, as if it is a disk file.

why is cat not working. can we write to a pty or read from a pty using open and write.

can we do this from java. java writes to a file that is actually a pty.

source of problem: forcing a program to flush its standard output when redirected

Update: is the question not clear. do i need to add more info?

output of ls -la

crw--w---- 1 iamrohitbanga users 1, 1 2010-01-13 18:27 pty1
crw--w---- 1 iamrohitbanga users 1, 2 2010-01-13 18:29 pty2

also

when i do cat /dev/pts/0 in one terminal and cat > /dev/pts/0 in another, i do not see the input of one getting transferred to another.

解决方案

That's not how PTYs work; you should read man 4 pty and man 4 pts. (The old BSD-style devices should no longer be used.)

In order to open a pseudo-terminal slave (PTS, the /dev/pts/# returned by ptsname(3)), another program must create a pseudo-terminal master (PTM, returned by posix_openpt(3)) and enable the PTS with grantpt(3) and unlockpt(3).

Using the forkpty(3) etc. helper functions is a lot easier than calling the low-level functions yourself.

And even after that, it doesn't work like a FIFO (which you seem to be expecting): anything written into the PTS comes out on the PTM, and anything read from the PTS is written from the PTM.

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