Variable in Bash Script that keeps it value from the last time running

Question

Can I create a Bash script with persistent variable-values?

For example, I initialize a variable with 0 when the script runs for the first time (during a specific time limit), and the variable increases automatically with every time the script is running.

Answer 1

You can't, but you can use a file to do it

#!/bin/bash

valuefile="/tmp/value.dat"

# if we don't have a file, start at zero
if [ ! -f "$valuefile" ]; then
    value=0

# otherwise read the value from the file
else
    value=$(cat "$valuefile")
fi

# increment the value
value=$((value + 1))

# show it to the user
echo "value: ${value}"

# and save it for next time
echo "${value}" > "$valuefile"