how can i past environment variables?

Shell Programming and Scripting
1

i am asking to do somethings like:
make use of 2 environment variables:
ASS1_DATA_DIR specifies the location of the input data files
ASS1_OUTPUT_DIR specifies the location of the output data files

i have something like that;
#set environment variables
set
VARIABLE1=ASS1_DATA_DIR
VARIABLE2=ASS1_OUTPUT_DIR

and then how can i use these variables to specifies the location of the files? and also when the variables is not set then i need to use the current working directory to search for files, how can i did this things?
Thank you

2 
if [ "$ASS1_DATA_DIR" ]; then

	VARIABLE1=$(echo $ASS1_DATA_DIR)
else
	VARIABLE1=$(pwd)
fi

VARIABLE2=$(echo $ASS1_OUTPUT_DIR)
3

so is it people can enter their own directory??
for VARIABLE2
when i produce a file called Marks
like >Marks
then what can i do for VARIABLE2??

4

Did not get you.

According to your original requirement,
the "VARIABLE1" of the "if" block contains the value of "ASS1_DATA_DIR" env var.

and as you said, if "ASS1_DATA_DIR" not set, you have to use the present working directory as "VARIABLE1" this is accomplished by the else block.

5

how about VARIABLE2, how can i use it??

6

try this:

if [ "$ASS1_DATA_DIR" ]; then

    VARIABLE1=$ASS1_DATA_DIR
else
    VARIABLE1=$(pwd)
fi
if [ "$ASS1_OUTPUT_DIR" ]; then

    VARIABLE2=$ASS1_OUTPUT_DIR
else
    VARIABLE2=$(pwd)
fi

or

VARIABLE1=${ASS1_DATA_DIR:- $(pwd)}
VARIABLE2=${ASS1_OUTPUT_DIR :- $(pwd)}

cheers,
Devaraj Takhellambam