how to parse a config file (*.conf) in shell script?

Question

I am new to shell script. I have a file app.conf as :

[MySql]
user = root
password = root123
domain = localhost
database = db_name
port = 3306

[Logs]
level = logging.DEBUG

[Server]
port = 8080

I want to parse this file in shell script and want to extract mysql credentials from the same. How can I achieve that?

Answer 1

I'd do this:

pw=$(awk '/^password/{print $3}' app.conf)

user=$(awk '/^user/{print $3}' app.conf)


echo $pw
root123

echo $user
root

The $() sets the variable pw to the output of the command inside. The command inside looks through your app.conf file for a line starting password and then prints the 3rd field in that line.

EDITED

If you are going to parse a bunch of values out of your config file, I would make a variable for the config file name:

CONFIG=app.conf
pw=$(awk '/^password/{print $3}' "${CONFIG}")
user=$(awk '/^user/{print $3}' "${CONFIG}")

Here's how to do the two different ports... by setting a flag to 1 when you come to the right section and exiting when you find the port.

mport=$(awk '/^\[MySQL\]/{f=1} f==1&&/^port/{print $3;exit}' "${CONFIG}")
sport=$(awk '/^\[Server\]/{f=1} f==1&&/^port/{print $3;exit}' "${CONFIG}")

Answer 2

You will want to search for "shell ini file parser". I would start with something like this:

ini_get () {
    awk -v section="$2" -v variable="$3" '
        $0 == "[" section "]" { in_section = 1; next }
        in_section && $1 == variable {
            $1=""
            $2=""
            sub(/^[[:space:]]+/, "")
            print
            exit 
        }
        in_section && $1 == "" {
            # we are at a blank line without finding the var in the section
            print "not found" > "/dev/stderr"
            exit 1
        }
    ' "$1"
}

mysql_user=$( ini_get app.conf MySql user )

Answer 3

Using awk:

awk -F ' *= *' '$1=="user"||$1=="password"{print $2}' my.cnf
root
gogslab

Answer 4

I ran in a similar problem yesterday and thought the best solution might be, if you get an associative array like "key - value" after parsing the file.

I you like to see a running example have a look at https://github.com/philippkemmeter/set-resolution/blob/master/set-resolution.

Adapted to your problem, this might work:

function receive_assoc_declare_statement {
    awk -F '=' 'BEGIN {ORS=" "}
    { 
        gsub(/[ \t]+/, "", $1); 
        gsub(/[ \t]+/, "", $2);
        print "[" $1 "]=" $2
    }' app.conf
}

eval 'declare -A CONF=('`receive_assoc_declare_statement`')'

You then have access to for instance user via ${CONF[user]}.

The gsub is trimming keys and values, so that you can use tab etc. to format your config file.

It's lacking sections, but you could add this functionality using sed to create one config array per section:

sed -n '/\[MySql\]/, /\[/ {p}' test.removeme | sed '1 d; $ d'

---

So answering your question in total, this script might work:

MYSQL=`sed -n '/\[MySql\]/, /\[/ {p}' app.conf | sed '1 d; $ d' | awk -F '=' 'BEGIN {ORS=" "}
{
    gsub(/[ \t]+/, "", $1); 
    gsub(/[ \t]+/, "", $2);
    print "[" $1 "]=" $2
}' `
eval 'declare -A MYSQL=('$MYSQL')'

The other sections correspondingly.