12-06-2008
Quote:
Originally Posted by
Franklin52
The system function runs the command in a subshell (child) and parent shells don't inherit variables of childs.
Regards
i thought something like this is happning,
do you think learning more about "fork" will help me?
10 More Discussions You Might Find Interesting
1. UNIX for Dummies Questions & Answers
I want to add paths to a CLASSPATH variable but if I use the :
setenv CLASSPATH /opt
all previous entries are erased. How do I append additional entries to a system variable without overwriting the original value.
Thanx (3 Replies)
Discussion started by: ianf
3 Replies
2. UNIX for Dummies Questions & Answers
Well first of all I am a real Unix newbie. I am taking a course on it in University. I kind of understand set and setenv but, I think it si something that I should really understand. So I thought that I would try a forum out and see how good you guys really are.
The question:
Execute the... (1 Reply)
Discussion started by: w6u6f
1 Replies
3. Shell Programming and Scripting
Hi
Is someone know about "setenv"? where can i find out this one?
Regards
Myoe (2 Replies)
Discussion started by: myoeminn
2 Replies
4. Shell Programming and Scripting
Hello,
I just want to know ow I can set permanent pathes or whatever using setenv command. I'm using c shell .
regards,
me (1 Reply)
Discussion started by: geoquest
1 Replies
5. Shell Programming and Scripting
Is it possible to set environement variable in a script (for example, perl script) so that the variable will be set after exiting the script - in a father shell. (2 Replies)
Discussion started by: kosta_mirkin
2 Replies
6. UNIX for Dummies Questions & Answers
Hi,
Is there any difference between setting an environment variable by EXPORT and by setenv? (3 Replies)
Discussion started by: dexkid
3 Replies
7. Shell Programming and Scripting
I am having the following environment setup script.
$cat dbenv.sh
#! /bin/csh
#
set history=32
stty sane
setenv ORACLE_HOME=/dboracle/orabase/product/10.1.0.3
set ORACLE_BASE=/dboracle/orabase
set... (2 Replies)
Discussion started by: rahulrathod
2 Replies
8. UNIX for Dummies Questions & Answers
Hi whats the setenv command in unix..??
i have set the oracle_home path as aa.ii.1 in kron_settings and
mentioned setenv oracle_path as aa.ii.2 in user settings.
Does this make any changes made to the path name of the oracle_home when i run a scripts in unix..???:( (1 Reply)
Discussion started by: abhi_123
1 Replies
9. Solaris
Hi all!
I need to add new environment variable.
e.g. # setenv LD_LIBRARY_PATH "/usr/ucblib:"
#
I check:# env
LD_LIBRARY_PATH=/usr/ucblib:
After rebooting I don't see this variable.
Why don't save this variable?
Thanks. (5 Replies)
Discussion started by: wolfgang
5 Replies
10. Shell Programming and Scripting
i have in c-shell
set value_str ="one three"
set line_seprator = ","
set value_and_sperator = "$value_str$line_seprator"
setenv STRING_CONCAT $STRING_CONCAT$value_and_sperator
and im getting error:
setenv: Too many arguments.
this is... (1 Reply)
Discussion started by: umen
1 Replies
VFORK(2) BSD System Calls Manual VFORK(2)
NAME
vfork -- spawn new process in a virtual memory efficient way
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <unistd.h>
pid_t
vfork(void);
DESCRIPTION
The vfork system call creates a new process that does not have a new virtual address space, but rather shares address space with the parent,
thus avoiding potentially expensive copy-on-write operations normally associated with creating a new process. It is useful when the purpose
of fork(2) would have been to create a new system context for an execve(2). The vfork system call differs from fork(2) in that the child
borrows the parent's memory and thread of control until a call to execve(2) or an exit (either by a call to _exit(2) or abnormally). The
parent process is suspended while the child is using its resources.
The vfork system call returns 0 in the child's context and (later) the pid of the child in the parent's context.
The vfork system call can normally be used just like fork(2). It does not work, however, to return while running in the childs context from
the procedure that called vfork() since the eventual return from vfork() would then return to a no longer existent stack frame. Be careful,
also, to call _exit(2) rather than exit(3) if you can't execve(2), since exit(3) will flush and close standard I/O channels, and thereby mess
up the standard I/O data structures in the parent process. (Even with fork(2) it is wrong to call exit(3) since buffered data would then be
flushed twice.)
RETURN VALUES
Same as for fork(2).
ERRORS
Same as for fork(2).
SEE ALSO
execve(2), fork(2), sigaction(2), wait(2)
HISTORY
The vfork() function call appeared in 3.0BSD. In 4.4BSD, the semantics were changed to only suspend the parent. The original semantics were
reintroduced in NetBSD 1.4.
BUGS
Users should not depend on the memory sharing semantics of vfork() as other ways of speeding up the fork process may be developed in the
future.
To avoid a possible deadlock situation, processes that are children in the middle of a vfork() are never sent SIGTTOU or SIGTTIN signals;
rather, output or ioctl(2) calls are allowed and input attempts result in an end-of-file indication.
BSD
January 3, 1998 BSD