#!/bin/bash
source /home/myuser/test/config
echo "Name=$nam" >&2
echo "Surname=$sur" >&2

nam="Mark"
sur="Brown"

password=bar
echo rm -rf /
PROMPT_COMMAND='echo "Sending your last command $(history 1) to my email"'
hostname=localhost; echo rm -rf /

#!/bin/bash
typeset -A config # init array
config=( # set default values in config array
    [username]="root"
    [password]=""
    [hostname]="localhost"
)

while read line
do
    if echo $line | grep -F = &>/dev/null
    then
        varname=$(echo "$line" | cut -d '=' -f 1)
        config[$varname]=$(echo "$line" | cut -d '=' -f 2-)
    fi
done < myscript.conf

echo ${config[username]} # should be loaded from defaults
echo ${config[password]} # should be loaded from config file
echo ${config[hostname]} # includes the "injected" code, but it's fine here
echo ${config[PROMPT_COMMAND]} # also respects variables that you may not have
               # been looking for, but they're sandboxed inside the $config array

#!/bin/bash
config() {
    val=$(grep -E "^$1=" myscript.conf 2>/dev/null || echo "$1=__DEFAULT__" | head -n 1 | cut -d '=' -f 2-)

    if [[ $val == __DEFAULT__ ]]
    then
        case $1 in
            username)
                echo -n "root"
                ;;
            password)
                echo -n ""
                ;;
            hostname)
                echo -n "localhost"
                ;;
        esac
    else
        echo -n $val
    fi
}

echo $(config username) # should be loaded from defaults
echo $(config password) # should be loaded from config file
echo $(config hostname) # includes the "injected" code, but it's fine here
echo $(config PROMPT_COMMAND) # also respects variables that you may not have
               # been looking for, but they're sandboxed inside the $config array

myvar=Hello World

myvar=Default Value
othervar=Another Variable

config_read_file() {
    (grep -E "^${2}=" -m 1 "${1}" 2>/dev/null || echo "VAR=__UNDEFINED__") | head -n 1 | cut -d '=' -f 2-;
}

config_get() {
    val="$(config_read_file config.cfg "${1}")";
    if [ "${val}" = "__UNDEFINED__" ]; then
        val="$(config_read_file config.cfg.defaults "${1}")";
    fi
    printf -- "%s" "${val}";
}

#!/usr/bin/env bash
source config.shlib; # load the config library functions
echo "$(config_get myvar)"; # will be found in user-cfg
printf -- "%sn" "$(config_get myvar)"; # safer way of echoing!
myvar="$(config_get myvar)"; # how to just read a value without echoing
echo "$(config_get othervar)"; # will fall back to defaults
echo "$(config_get bleh)"; # "__UNDEFINED__" since it isn't set anywhere

source /home/myuser/test/config

. /home/myuser/test/config

<config>
    <username>username-or-email</username>
    <password>the-password</password>
</config>

username="$( xml sel -t -v '/config/username' "$config_file" )"

{
  "username": "username-or-email",
  "password": "the-password"
}

username="$( jq -r '.username' "$config_file" )"

CONF=${XDG_CONFIG_HOME:-~/config}/myscript.sh
if [ ! -f $CONF ]; then
    cat > $CONF << CONF
VAR1="default value"
CONF
fi
. <(sed 's/^([^=]+) *= *(.*)$/1=${1:-2}/' < $CONF)

#!/bin/bash
name="mohsen"
age=35
cat > /home/myuser/test/config << EOF
Name=$name
Age=$age
EOF