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Extracting value of a variable

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# 8  
Old 09-15-2015
Quote:
Originally Posted by guknvivek
My requirement in simple words,

Var1="Value"
Var2=Var1

I want to assign "Value" to Var2. As per my original post, If I have a number instead of "value" then I am able to retrieve it.

Thanks
So you want to turn a variable name into its contents?

If you have a new enough shell, you can do this:

Code:
VAR="asdf"
VARNAME="VAR"

echo "${!VARNAME}"

You can do the opposite, setting any variable name you want, with this trick:

Code:
VARNAME="VAR"

read "$VARNAME" <<EOF
VALUE
EOF

echo $VAR

This User Gave Thanks to Corona688 For This Post:
sea
# 9  
Old 09-15-2015
DON'T use arithmetic expansion when assigning a variable's contents to another var. Use VAR2="$VAR1".
# 10  
Old 09-15-2015
If you have no idea what the variable name is from the sourced file nor its contents then you could diff the ENVIRONMENT before and after sourcing this would give the variables and their contents.
However here is an idea that finds the variable name, its contents and transfers the contents into another variable...
Code:
#!/bin/sh
# value
# Create a simple test file to open up...
echo 'VAR1=125' > /tmp/variable
# VAR1=125 sourced from $1...
$1
# Obtaining the filename from $1, firstly create a simple array.
VAR2=( $1 )
# The second part of the string is the /full/path/to/filename.
VAR2=${VAR2[1]}
# Save the contents of the file to variable VAR2, VAR1 belongs to the sourced file.
VAR2=$(cat $VAR2)
# Show the variable and its value.
echo $VAR2
# Create a new local variable.
MYVAR=""
# Find the sourced variable name.
for n in $( seq 0 1 ${#VAR2} )
do
	if [ "${VAR2:$n:1}" == "=" ]
	then
		break
	fi
	MYVAR=$MYVAR${VAR2:$n:1}
done
echo "The sourced variable name is $MYVAR..."
# Now dump the contents of $MYVAR, 'VAR1' into a reused variable VAR2.
eval VAR2='$'"$MYVAR"
echo "The sourced variable value is $VAR2..."

Results:-
Code:
Last login: Tue Sep 15 19:48:21 on ttys000
AMIGA:barrywalker~> cd Desktop/Code/Shell
AMIGA:barrywalker~/Desktop/Code/Shell> ./value 'source /tmp/variable'
VAR1=125
The sourced variable name is VAR1...
The sourced variable value is 125...
AMIGA:barrywalker~/Desktop/Code/Shell> _

If you want to get all the variables, their contents and transfer to your local variables from a script then this is much more difficult...
# 11  
Old 09-17-2015
Hi,

I have again explained my requirement.

FileA has this content:
Code:
Variable1="Value";

In the script, which is invoked by a single parameter.
./value_extractor.sh Variable1
Code:
. FileA
Retrieved_value=`echo $[$1]`
echo $Retrieved_value
exit 0

# 12  
Old 09-17-2015
Please read my previous post. I explain how to use a variable containing a variable name to get the contents of that other variable.
This User Gave Thanks to Corona688 For This Post:
guknvivek
# 13  
Old 09-17-2015
Puzzled; is this what you are after?
OSX 10.7.5, default terminal running 'sh'...
Code:
#!/bin/sh
# Value_extractor.sh Variable1
echo 'Variable1="This is a string...";' > /tmp/FileA
. /tmp/FileA
eval echo '$'"$1" > /tmp/someval
Retrieved_value=$( cat /tmp/someval )
echo $Retrieved_value

Results:=
Code:
Last login: Thu Sep 17 20:15:40 on ttys000
AMIGA:barrywalker~> cd Desktop/Code/Shell
AMIGA:barrywalker~/Desktop/Code/Shell> chmod 755 Value_extractor.sh
AMIGA:barrywalker~/Desktop/Code/Shell> ./Value_extractor.sh Variable1
This is a string...
AMIGA:barrywalker~/Desktop/Code/Shell> _

This User Gave Thanks to wisecracker For This Post:
guknvivek
# 14  
Old 09-17-2015
Thanks Corona688.. The '!' helped us to retrieve the value. Thanks again.
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