writing to child process stdin

avikosan · 11-11-2003, 05:25 PM

I try to write a program (in C) that fork() a child process and in that child process runs another executable (with execv()) .

I need to write to this child process stdin (the child process waits for input).

I tried to use pipe() to create a pipe between the parent (my) process and the child process, that everything that I write to my stdout goes into the child stdin.

it seems like it has some problem with the newline.

does anybody has an idea ?

Avikosan

lenlutz · 11-11-2003, 05:51 PM

i have only done this a few thousand times

Named_pipe or MessageQueues....

if you need a few samples, email me......

i dont THINK, you can do what you discribed, since, the pipe must exist,
Before the child starts....(other then with a namedPipe)

Hense grep xyz file | pg
stdout is already directed, Before pg is started (all by shell)

dont give me too much he!!... i could be wrong, but, ive used msgque for years

infamous41md · 11-11-2003, 07:06 PM

1)create a pipe in parent
2)fork child
3)dup2 the read end of pipe in child to stdin dup2(pipefd, STDIN_FILENO)
4)now close the read and write end of the pipe in the child
5)close the read end of the pipe in parent
6)now u have the write end of the pipe in the parent tied to the childs stdin
7)when done, BE SURE TO CLOSE WRITE END OF PIPE IN PARENT else child will never read EOF
8)see here www.1nfamus.netfirms.com for a command shell i wrote if u need more help

peace