Hi, I will try to keep my post as compressed as my title was.
I am writing on pseudo code on a recursive function that I want to read from the one-above function-run and then give the result to the function-run down below until a stop is triggered. Example:
Code:
$ ls -la | grep x | sort
In my function what I want ls to run and send the result to the next function call.
What I've got so far:
Code:
main:
create a char **program_names and set int times_to_run to amount of names.
call rec(program_names, times_to_run)
rec(char** program_names, int times_to_run):
if times_to_run is 0 return, else do
int fd[2]
pipe(fd)
replace stdout with fd[1]
fork
parent:
execl(*(program_names+times_to_run))
child:
replace stdin with fd[0]
//waitpid(getppid()) ?
call rec(program_names, times_to_run-1)
Does this seem right? I'm having a hard time with recursion.
Cheers.
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Discussion started by: dano88
2 Replies
LEARN ABOUT HPUX
pipe
pipe(2) System Calls Manual pipe(2)NAME
pipe() - create an interprocess channel
SYNOPSIS DESCRIPTION
creates an I/O mechanism called a pipe and returns two file descriptors, fildes[0] and fildes[1]. fildes[0] is opened for reading and
fildes[1] is opened for writing.
A read-only file descriptor fildes[0] accesses the data written to fildes[1] on a first-in-first-out (FIFO) basis. For details of the I/O
behavior of pipes see read(2) and write(2).
By default, HP-UX pipes are not STREAMS-based. It is possible to generate the kernel so that all pipes created on a system are STREAMS-
based. This can only be done for HP-UX releases 10.0 and later. STREAMS-based FIFOs (created by or are not supported on HP-UX.
To generate a kernel that supports STREAMS-based pipes:
o STREAMS/UX must be installed.
o The module and the driver must be included in the file. (When STREAMS/UX is installed, and are automatically added to the system
file.)
o The tunable parameter (see streampipes(5)) must be set to 1 in the file. (This is not automatically done when STREAMS/UX is
installed.)
o The kernel must be generated and the system rebooted. Once this is done, all pipes created by will be STREAMS-based.
For more information, see
EXAMPLES
The following example uses to implement the command string
RETURN VALUE
returns one of the following values:
Successful completion.
Failure.
is set to indicate the error.
ERRORS
sets to one of the following error values if the corresponding condition is true.
or more file descriptors are currently open.
The system file table is full.
The file system lacks sufficient space to create the pipe.
Could not allocate resources for both Stream heads
(STREAMS-based pipes only).
SEE ALSO sh(1), read(2), write(2), popen(3S), privileges(5), streampipes(5), streamio(7).
STANDARDS CONFORMANCE pipe(2)
07-05-2012
