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Top Forums Shell Programming and Scripting Need help on Assigning a Array variable from Background Functions Post 302910176 by Don Cragun on Wednesday 23rd of July 2014 01:38:03 AM
Old 07-23-2014
Starting a pipeline in the background creates a new shell execution environment. Variables set in that new shell execution environment are not visible in the parent (foreground) shell execution environment.

There are several ways things like this can be done. One way that works if the values you want to produce in the background are always less than or equal to 255, is:
Code:
#!/bin/ksh
exec_func() {
	sleep 1
	printf 'exec_func exiting with %d\n' "$(( $1 + 100 ))"
	exit $(( $1 + 100 ))
}

date
for i in 1 2
do	exec_func $i&
	pid[i]=$!
done
for i in 1 2
do	wait ${pid[i]}
	OUT_ARR[i]=$?
done
date
print ${OUT_ARR[@]}

which produces the output:
Code:
Tue Jul 22 22:27:03 PDT 2014
exec_func exiting with 102
exec_func exiting with 101
Tue Jul 22 22:27:04 PDT 2014
101 102

but the order of the two lines in red may vary from run to run (and may be intermixed on a multi-processor system).
This User Gave Thanks to Don Cragun For This Post:
 

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newtask(1)                                                         User Commands                                                        newtask(1)

NAME
newtask - create new task and optionally change project SYNOPSIS
newtask [-p project] [-v] [-c pid | [-Fl] [command...]] DESCRIPTION
The newtask command executes the user's default shell or a specified command, placing the executed command in a new task owned by the spec- ified project. The user's default shell is the one specified in the passwd database, and is determined using getpwnam(). Alternatively, newtask can be used to cause an already running process to enter a newly created task. A project for the new task can also be specified in this form of the command. This might be desirable for processes that are mission critical and cannot be restarted in order to put them into a new project. In the case that extended accounting is active, the newtask command can additionally cause the creation of a task accounting record marking the completion of the preceding system task. OPTIONS
The following options are supported: -c pid Cause a running process to enter a newly created task. A project for the new task can also be specified using the -p option. The invoking user must either own the process or have super-user privileges. If the project is being changed, the process owner must be a member of the specified project, or the invoking user must have super-user privileges. When the project is changed for a running process, its pool binding as well as resource controls are modi- fied to match the configuration of the new project. Controls not explicitly specified in the project entry is preserved. This option is incompatible with the -F and -l options. -F Creates a finalized task, within which further newtask or settaskid(2) invocations would fail. Finalized tasks can be useful at some sites for simplifying the attribution of resource consumption. -l Changes the environment to what would be expected if the user actually logged in again as a member of the new project. -p Changes the project ID of the new task to that associated with the given project name. The invoking user must be a valid member of the requested project, or must have super-user privileges, for the command to succeed. If no project name is specified, the new task is started in the invoking user's current project. -v Verbose: displays the system task id as the new system task is begun. OPERANDS
The following operands are supported: project The project to which resource usage by the created task should be charged. The requested project must be defined in the project databases defined in nsswitch.conf(4). command The command to be executed as the new task. If no command is given, the user's login shell is invoked. (If the login shell is not available, /bin/sh is invoked.) EXAMPLES
Example 1: Creating a New Shell The following example creates a new shell in the canada project, displaying the task id: example$ id -p uid=565(gh) gid=10(staff) projid=10(default) example$ newtask -v -p canada 38 example$ id -p uid=565(gh) gid=10(staff) projid=82(canada) Example 2: Running the date Command The following example runs the date command in the russia project: example$ newtask -p russia date Tue Aug 31 11:12:10 PDT 1999 Example 3: Changing the Project of an Existing Process The following example changes the project of the existing process with a pid of 9999 to russia: example$ newtask -c 9999 -p russia EXIT STATUS
The following exit values are returned: 0 Successful execution. 1 A fatal error occurred during execution. 2 Invalid command line options were specified. FILES
/etc/project Local database containing valid project definitions for this machine. /proc/pid/* Process information and control files. ATTRIBUTES
See attributes(5) for a description of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWcsu | +-----------------------------+-----------------------------+ SEE ALSO
proc(1), id(1M), poolbind(1M), execvp(2), setrctl(2), settaskid(2), setproject(3PROJECT), nsswitch.conf(4), proc(4), project(4), attributes(5) SunOS 5.10 17 Nov 2004 newtask(1)
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