UNIX for Dummies Questions & Answers

Hello,

I have a file, inputs.list that contain prefixes to files that are inputs for a program

inputs.list
A
B
C
D
E
...

My files are of the format A_1, A_2, B_1, B_2 and so on. I am planning to run a shell script that takes each line from the above file and feed it to the runProg.sh script as shown below:

Code:

#!/bin/sh

while read x
do
./runProg.sh $x_1 $x_2
done < inputs.list

However this throws an error. How can I append "_" to the variable $x?

Thanks for your input!
~Gus

${x}_1

Code:

"$x"_1

additionally is robust regarding special characters.

Variables do not work that way.

If you are in BASH, you can do this:

Code:

VARNAME="${X}_1"
echo "contents are ${!VARNAME}"

...but dynamic variable names are generally a terrible idea. They allow outside things to specify arbitrary variables in your program, making a security nightmare.