I got varying results for each time I ran it. Fifo redirection for each write statement malfunctions here.
It does not malfunction, the subprocess opens and closes stdout and therefore the varying results. I used a sleep statement so that the reading process would be reading before the subprocess started opening the pipe...
Last edited by Scrutinizer; 03-26-2012 at 04:17 PM..
This User Gave Thanks to Scrutinizer For This Post:
Hi,
I am running a series of scripts and I need to transport a particular variable across many scripts. I thougt of defining an environmental variable which I could access through. But I found that the variable dies as soon as the script ends..
Currently I write this variable to a temporary... (2 Replies)
I'm having an issue when I export within my program. I'm getting the variable name, not the variable value. I have a configuration file (config.txt) that has the values of the variables set as so:
set -a
export ARCHIVEPOSourceDir="/interfaces/po/log /interfaces/po/data"
export... (2 Replies)
I have always used the "$$" environment variable to find the current process number. Is there any similar way or perhaps something else to easily find the parent process number? I realize I could do something like ps and grep for the process and cut or awk out the parent process but I wanted to... (1 Reply)
hi experts(novice people can stay away as it is no child's game),
i am developing a script which works like recycle bin of windows.
the problem i am facing is that when ever i am trying to delete a file which is situated in parent directory or parent's parent directory i am unable to... (1 Reply)
Hi All,
I have a script which calls a child script with a parameter to be run in the background
. childscript.ksh $a &
Can any one suggest me how do i export a variable from the child script to parent script?
Note that the child script is in background
If the child script is in... (3 Replies)
Hi,
I have a number of Makefiles, including a couple of files that I include in Makefiles, a few scripts that are executed through Makefiles, and I have problems with environment variables that are not inherited to the scripts properly.
Simplified scenario:
rootdir/Makefile:
all:
... (1 Reply)
Hi,
I was trying to do something where I would be able to export one local variable in a telnet subshell to its parent shell.
I found something like this over here, but couldnt exactly understand it :(.
I am referring to this part actually:
#! /usr/bin/ksh
exec 4>&1
tail -5 >&4 |&
exec... (4 Replies)
I have a shell script I want to run that will set environment variables based on the value of an input variable submitted when the shell script is called. For example:
$ mgenv.sh prod
This would set environment variables for prod
$ mgenv.sh test
This would set environment variables... (1 Reply)
I'm a BASH shell user (relatively new)
I need to get a variable calculated in a subshell, outside the subshell, when it completes. I can do it, by writing the variable into a file, and then reading the file again when outside the subshell. I've tried lots of things from exporting to environmental... (3 Replies)
I have a simple script to log network connectivity to a set of systems.
However, as expected the date appended to the log never changes because the new variable is lost when the loop starts again. Can someone clue me in on how to get around this issue?
#!/bin/bash
LOG=/tmp/netlog... (3 Replies)
Discussion started by: woodson2
3 Replies
LEARN ABOUT REDHAT
mkfifo
MKFIFO(3) Linux Programmer's Manual MKFIFO(3)NAME
mkfifo - make a FIFO special file (a named pipe)
SYNOPSIS
#include <sys/types.h>
#include <sys/stat.h>
int mkfifo(const char *pathname, mode_t mode);
DESCRIPTION
mkfifo makes a FIFO special file with name pathname. mode specifies the FIFO's permissions. It is modified by the process's umask in the
usual way: the permissions of the created file are (mode & ~umask).
A FIFO special file is similar to a pipe, except that it is created in a different way. Instead of being an anonymous communications chan-
nel, a FIFO special file is entered into the file system by calling mkfifo.
Once you have created a FIFO special file in this way, any process can open it for reading or writing, in the same way as an ordinary file.
However, it has to be open at both ends simultaneously before you can proceed to do any input or output operations on it. Opening a FIFO
for reading normally blocks until some other process opens the same FIFO for writing, and vice versa. See fifo(4) for non-blocking handling
of FIFO special files.
RETURN VALUE
The normal, successful return value from mkfifo is 0. In the case of an error, -1 is returned (in which case, errno is set appropriately).
ERRORS
EACCES One of the directories in pathname did not allow search (execute) permission.
EEXIST pathname already exists.
ENAMETOOLONG
Either the total length of pathname is greater than PATH_MAX, or an individual file name component has a length greater than
NAME_MAX. In the GNU system, there is no imposed limit on overall file name length, but some file systems may place limits on the
length of a component.
ENOENT A directory component in pathname does not exist or is a dangling symbolic link.
ENOSPC The directory or filesystem has no room for the new file.
ENOTDIR
A component used as a directory in pathname is not, in fact, a directory.
EROFS pathname refers to a read-only filesystem.
CONFORMING TO
POSIX.1
SEE ALSO mkfifo(1), read(2), write(2), open(2), close(2), stat(2), umask(2), fifo(4)Linux 1.2.13 1995-09-03 MKFIFO(3)