11-12-2008
How to export a variable from a child process running in background to the parent
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 foreground that is not an issue.
Also can any one suggest me how to get back the exit status (of say exit 0 ) from any of the functions in the child script to the parent script, again in this case the child script is running in the background.
Thanks
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LEARN ABOUT OPENDARWIN
fork
FORK(2) BSD System Calls Manual FORK(2)
NAME
fork -- create a new process
SYNOPSIS
#include <sys/types.h>
#include <unistd.h>
pid_t
fork(void);
DESCRIPTION
Fork() causes creation of a new process. The new process (child process) is an exact copy of the calling process (parent process) except for
the following:
o The child process has a unique process ID.
o The child process has a different parent process ID (i.e., the process ID of the parent process).
o The child process has its own copy of the parent's descriptors. These descriptors reference the same underlying objects, so that,
for instance, file pointers in file objects are shared between the child and the parent, so that an lseek(2) on a descriptor in the
child process can affect a subsequent read or write by the parent. This descriptor copying is also used by the shell to establish
standard input and output for newly created processes as well as to set up pipes.
o The child processes resource utilizations are set to 0; see setrlimit(2).
RETURN VALUES
Upon successful completion, fork() returns a value of 0 to the child process and returns the process ID of the child process to the parent
process. Otherwise, a value of -1 is returned to the parent process, no child process is created, and the global variable errno is set to
indicate the error.
ERRORS
Fork() will fail and no child process will be created if:
[EAGAIN] The system-imposed limit on the total number of processes under execution would be exceeded. This limit is configuration-
dependent.
[EAGAIN] The system-imposed limit MAXUPRC (<sys/param.h>) on the total number of processes under execution by a single user would
be exceeded.
[ENOMEM] There is insufficient swap space for the new process.
SEE ALSO
execve(2), wait(2)
HISTORY
A fork() function call appeared in Version 6 AT&T UNIX.
4th Berkeley Distribution June 4, 1993 4th Berkeley Distribution