从C UNIX中的外部文件（或控制文件）中插入两个文件

Question

Hi i am having trouble wrapping my head around this concept.

I need to execute two files lets say ac & bc from a control file called control.c

I want to pipe the output of ac to the input of bc

I understand that file descriptors(fd): fd 0 = stdin fd 1 = stdout

I understand that creating a pipe requires an array of integers (two fds)

e.g.
zpipe[2]
pipe(zpipe)

i want to execute the files a and b and pipe the output of a to the input of b.

however i am confused at the concept as opening or reading said files would create a new fd. I understand the fd of a (eg fda) can be set to 0 by calling fda = dup2 (fd,0). Would this not break the pipe as 0 is now closed?

if i called

execvp("a.c", args)
execvp("b.c", args)

how would i ensure these files are correctly piped and waited for?

Answer 1

You would probably want to use a pipe and fork to get the desired results. Take a look at the answers to this question .

Answer 2

Figured it out. i was attempting to run execvp with user defined programs. where i called execvp("ac, args)

I should of been calling

execvp("./a", args)

Rookie mistake my apologies