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Full Discussion: Environment variables
Top Forums Shell Programming and Scripting Environment variables Post 302631099 by jim mcnamara on Thursday 26th of April 2012 07:38:49 PM
Old 04-26-2012
IF you source a script the environment variables persist. A sourced script should not call exit or you will be logged out.

Two ways to source a script named env.sh
Code:
. env.sh
source env.sh

Those tools probably had you running inside a child process, with the parent process killed off. So when you exit the now-current child process, you log out.

Another more sensible approach: In C/perl you can all exec to run a command like "bash -c env.sh" to set variables. Which is probably what the perl code did. This does not create a child it replaces the old process. This is also what sourcing does.

Last edited by jim mcnamara; 04-26-2012 at 08:45 PM..
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USE(1)								   User Commands							    USE(1)

NAME
use - Frontend to the Usepackage Environment Manager SYNOPSIS
csh and derivatives: source /usr/share/usepackage/use.csh bourne shell and derivatives: source /usr/share/usepackage/use.bsh korn shell: . /usr/share/usepackage/use.ksh use [-vs] [-f file] package ... use -l DESCRIPTION
Usepackage is an environment management program. It is based on the principle of packages - collections of executables that share a common set of necessary environment variables, such as PATH, MANPATH or LD_LIBRARY_PATH. For each given package, use sources the appropriate environment information into the current shell. The environment information is speci- fied in a configuration file, see usepackage(1). OPTIONS -v Output verbose information to the standard error stream. -s Silence warnings for un-matched packages. This is useful in a shell rc script when a package is known not to be available on all architectures that the shell is used on. -f file Specify an alternate initial configuration file. -l List available packages and groups. FILES
/usr/share/usepackage/usepackage.conf The default configuration file. /usr/share/usepackage/use.csh Shell setup for csh and derivatives. /usr/share/usepackage/use.bsh Shell setup for bourne shell and derivatives. /usr/share/usepackage/use.ksh Shell setup for ksh. /usr/bin/usepackage The underlying Usepackage executable. ENVIRONMENT
Other than the reading and re-definition of environment variables for package setup, use also uses the following environment variables for user configuration: PACKAGES_PATH Colon-separated path list giving the directories to search for configuration files. Shell-style tilde (~) user-directory escapes are expanded. HOME If present in the environment, this is used to provide the expansion for the tilde (~) user-directory. SHELL If present in the environment, the last path component of this is used for shell matching (see SYNTAX) and detecting the style of environment output that should be used, see usepackage(1). COPYRIGHT
Usepackage Environment Manager Copyright (C) 1995-2005 Jonathan Hogg This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MER- CHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA SEE ALSO
usepackage(1), csh(1), sh(1), ksh(1) Usepackage $Date: 2005/12/11 16:42:09 $ USE(1)
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