topic Re: defining a global variable in Operating System - HP-UX

defining a global variable

Pando — Mon, 21 Mar 2005 03:30:53 GMT

i would like to ask hot to define a global and local variable in a script?

Re: defining a global variable

Noel Miranda — Mon, 21 Mar 2005 03:40:26 GMT

What exactly do you mean by global?

Re: defining a global variable

Indira Aramandla — Mon, 21 Mar 2005 03:44:32 GMT

Hi Fernando,

A global variable is global to the script and can be accessed anywhere in the script. A local variable is local to a function or a loop which can be referred in the function or the loop.
eg:

count=0; is defining the variable counter as number and initialising to zero.
counterflag="y" is defining the variable counterflag as character and initialising to "y"

IA

Re: defining a global variable

Peter Godron — Mon, 21 Mar 2005 03:49:10 GMT

Fernando,
can you please expand on what you want to know.
Do you want to know how variables are used with a script (i.e. passing data between procedures with the same script)
or
how to change variables in your environment with a script (i.e. ORACLE_HOME etc).
Variables defined in script are local to that script, unless exported.
I believe all variables in a script are global to that script:
#!/usr/bin/sh
testing()
{
a=2
echo "Testing [$a]"
}
a=0
echo "main [$a]"
testing
echo "main [$a]"

will result in:
main [0]
Testing [2]
main [2]

Regards

Regards

Re: defining a global variable

Pando — Mon, 21 Mar 2005 04:19:45 GMT

Basically, i want to know how variables are used within a script (i.e. passing data between procedures with the same script)? Are they accessible anywhere within the script?

Re: defining a global variable

Leif Halvarsson_2 — Mon, 21 Mar 2005 04:23:12 GMT

Hi,

Just export the variable.

Re: defining a global variable

Peter Godron — Mon, 21 Mar 2005 04:52:03 GMT

Fernando,
see my earlier example.
The variable (a) is visible throughout the script.
Regards

Re: defining a global variable

Artyom Voronchihin — Mon, 21 Mar 2005 06:24:05 GMT

Hello!

Local variables are available within a single shell instance. If other instances of a shell are invoked by a script, you need to define global variables, those can be inherited by child shells.
For example:

var="0" #defines local variable named var with value 0.

export var #makes variable global.

Re: defining a global variable

Andrew Cowan — Tue, 22 Mar 2005 02:49:45 GMT

If you want a variable to be available to everybody at all times, export it in "/etc/profile".

Re: defining a global variable

Muthukumar_5 — Tue, 22 Mar 2005 05:42:40 GMT

We can define global variables with login startup scripts, /etc/profile or home directory profile file.

Normal script variables are treated as local for that script.

test="hai" # Local variable

IF you want to include multiple file variables then try as,

-- head.ksh --
# varaiable file
Name="test"
age="23"

#!/bin/ksh
. ./head.ksh

echo $name
echo $age

It will get information from head.ksh as header (include) file and print the data.

HTH.

Re: defining a global variable

Lawrence Mahan — Tue, 22 Mar 2005 10:52:30 GMT

In general all shell variable are global within a shell script. However: If you are calling non shell routines within the script then the varables within those routines will be local to that routine. What I meen by a non shell routine is if you are using awk, perl, sql, or other executables that can be called in-line from shell that is not shell. Usually you will have to pass varables to this routines. I.E. awk -v INDATE=${INDATE}

Re: defining a global variable

A. Clay Stephenson — Tue, 22 Mar 2005 11:17:48 GMT

Actually, one can have local variables within a shell script. Those defined in functions via the typeset command are local to the function. Run this script and it should make variable scoping clear.

--------------------------------------------
#!/usr/bin/sh

typeset -i I=100 # global
typeset GLOVAR="Global String"

func1()
{
typeset -i I=1 # local definition

echo "I in func1 = ${I}"
echo "GLOVAR in func1 = ${GLOVAR}"
return 0
} # func1

func2()
{
typeset -i I=2 # local definition

echo "I in func2 = ${I}"
echo "GLOVAR in func2 = ${GLOVAR}"
return 0
} # func2

func1
func2
echo "I in main = ${I}"
echo "GLOVAR in main = ${GLOVAR}"
exit 0

----------------------------------------

It's considered good practice to typeset all variables in scripts. Of course, any of these can be exported and made available to child processes.