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Top Forums Shell Programming and Scripting How to export a variable from a subshell to the parent shell? Post 302612439 by vomv1988 on Monday 26th of March 2012 01:04:09 AM
Old 03-26-2012
Quote:
Originally Posted by Chubler_XL
What happens if you have more than 1 instance if this script running?

I would suggest generating a temp filename for the pipe and passing it to the child.
Excellent point. Then, maybe something like:
Code:
#!/bin/bash

TMPFIFO="/tmp/fifo.$$"
 
mknod $TMPFIFO p
 
(
       echo 'value' > $TMPFIFO &
)
 
VARIABLE=`cat $TMPFIFO`
rm $TMPFIFO

Thank you.

Last edited by vomv1988; 03-26-2012 at 02:15 AM..
 

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mknod(8)						      System Manager's Manual							  mknod(8)

NAME
mknod - Creates a special file SYNOPSIS
/usr/sbin/mknod special_file [ b major_device# minor_device# | c major_device# minor_device#] /usr/sbin/mknod filename p DESCRIPTION
The mknod command makes a directory entry. The first argument is the name of the special device file. Select a name that is descriptive of the device. The mknod command has two forms. In the first form, the second argument is the b or c flag. The last two arguments are numbers specifying the major_device, which helps the operating system find the device driver code, and the minor_device, the unit drive, or line number, which may be either decimal or octal. The assignment of major device numbers is specific to each system. You can determine the device numbers by examining the conf.c system source file. If you change the contents of the conf.c file to add a device driver, you must rebuild the kernel. In the second form of mknod, you use the p flag to create named pipes (FIFOs). Only the superuser can create a character or device special file. FLAGS
Indicates that the special file corresponds to a block-oriented device (disk or tape) Indicates that the special file corresponds to a character-oriented device Creates named pipes (FIFOs) EXAMPLES
To create the special file for a new drive, /dev/disk/dsk20, with a major device number of 1 and a minor device number of 2, enter: mknod /dev/disk/dsk20 b 1 2 This command creates the special file, /dev/disk/dsk20, which is a block special file with major device number 1 and minor device number 2. To create a pipe named fifo, enter: mknod fifo p This command creates the pipe fifo, which is not necessarily in the current directory. FILES
Specifies the command path Specifies the system device numbers specification file delim off mknod(8)
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