Bash variables

cat vars.sh

#!/usr/bin/env bash
#File: vars.sh

x=5
echo "The value of x is $x"
let x=$x+1
echo "The value of x is $x"
num_lines=$(cat vars.sh | wc -l)
echo "The number of lines in this file is $num_lines"

bash vars.sh

The value of x is 5
The value of x is 6
The number of lines in this file is 9

cat args.sh

#!/usr/bin/env bash
#File: args.sh

file_lines=$(cat $1 | wc -l)
echo "The numer of lines in $1 is $file_lines"

bash args.sh args.sh

The numer of lines in args.sh is 5

bash args.sh vars.sh

The numer of lines in vars.sh is 9