Parsing variables from config file in Bash

Question

Having the following content in a file:

VARIABLE1="Value1"
VARIABLE2="Value2"
VARIABLE3="Value3"

I need a script that outputs the following:

Content of VARIABLE1 is Value1
Content of VARIABLE2 is Value2
Content of VARIABLE3 is Value3

Any ideas?

Answer 1

If you need these...

Features

• Single line and inline comments;
• Trimming spaces around = (ie var = value will not fail);
• Quoted string values;
• Understanding of DOS line endings;
• Keep safe, avoiding sourcing your config file.

Code

shopt -s extglob
configfile="dos_or_unix" # set the actual path name of your (DOS or Unix) config file
tr -d '\r' < $configfile > $configfile.unix
while IFS='= ' read -r lhs rhs
do
    if [[ ! $lhs =~ ^\ *# && -n $lhs ]]; then
        rhs="${rhs%%\#*}"    # Del in line right comments
        rhs="${rhs%%*( )}"   # Del trailing spaces
        rhs="${rhs%\"*}"     # Del opening string quotes 
        rhs="${rhs#\"*}"     # Del closing string quotes 
        declare $lhs="$rhs"
    fi
done < $configfile.unix

Comments

tr -d '\r' ... deletes DOS carriage return.
! $lhs =~ ^\ *# skips single line comments and -n $lhs skips empty lines.
Deleting trailing spaces with ${rhs%%*( )} requires setting extended globbing with shopt -s extglob. (Apart using sed), you can avoid this, via the more complex:

rhs="${rhs%"${rhs##*[^ ]}"}"  

Test config file

## This is a comment 
var1=value1             # Right side comment 
var2 = value2           # Assignment with spaces 

## You can use blank lines 
var3= Unquoted String   # Outer spaces trimmed
var4= "My name is "     # Quote to avoid trimming 
var5= "\"Bob\""         

Test code

echo "Content of var1 is $var1"
echo "Content of var2 is $var2"
echo "Content of var3 is [$var3]"
echo "Content of var4 + var5 is: [$var4$var5]"

Results

Content of var1 is value1
Content of var2 is value2
Content of var3 is [Unquoted String]
Content of var4 + var5 is: [My name is "Bob"]

Answer 2

awk '{print "Content of "$1" is "$3}' FS='[="]'

Result

Content of VARIABLE1 is Value1
Content of VARIABLE2 is Value2
Content of VARIABLE3 is Value3

Answer 3

    # 
    #------------------------------------------------------------------------------
    # parse the ini like $0.$host_name.cnf and set the variables
    # cleans the unneeded during after run-time stuff. Note the MainSection
    # courtesy of : http://mark.aufflick.com/blog/2007/11/08/parsing-ini-files-with-sed
    #------------------------------------------------------------------------------
    doParseConfFile(){
        # set a default cnfiguration file
        cnf_file="$run_unit_bash_dir/$run_unit.cnf"

        # however if there is a host dependant cnf file override it
        test -f "$run_unit_bash_dir/$run_unit.$host_name.cnf" \
            && cnf_file="$run_unit_bash_dir/$run_unit.$host_name.cnf"

        # yet finally override if passed as argument to this function
        # if the the ini file is not passed define the default host independant ini file
        test -z "$1" || cnf_file=$1;shift 1;


        test -z "$2" || ini_section=$2;shift 1;
        doLog "DEBUG read configuration file : $cnf_file"
        doLog "INFO read [$ini_section] section from config file"

        # debug echo "@doParseConfFile cnf_file:: $cnf_file"
        # coud be later on parametrized ...
        test -z "$ini_section" && ini_section='MAIN_SETTINGS'

        doLog "DEBUG reading: the following configuration file"
        doLog "DEBUG ""$cnf_file"
        ( set -o posix ; set ) | sort >"$tmp_dir/vars.before"

        eval `sed -e 's/[[:space:]]*\=[[:space:]]*/=/g' \
            -e 's/#.*$//' \
            -e 's/[[:space:]]*$//' \
            -e 's/^[[:space:]]*//' \
            -e "s/^\(.*\)=\([^\"']*\)$/\1=\"\2\"/" \
            < $cnf_file \
            | sed -n -e "/^\[$ini_section\]/,/^\s*\[/{/^[^#].*\=.*/p;}"`

        ( set -o posix ; set ) | sort >"$tmp_dir/vars.after"

        doLog "INFO added the following vars from section: [$ini_section]"
        cmd="$(comm -3 $tmp_dir/vars.before $tmp_dir/vars.after | perl -ne 's#\s+##g;print "\n $_ "' )"
        echo -e "$cmd"
        echo -e "$cmd" >> $log_file
        echo -e "\n\n"
        sleep 1; printf "\033[2J";printf "\033[0;0H" # and clear the screen
    }
    #eof func doParseConfFile

Answer 4

Since your config file is a valid shell script, you can source it into your current shell:

. config_file
echo "Content of VARIABLE1 is $VARIABLE1"
echo "Content of VARIABLE2 is $VARIABLE2"
echo "Content of VARIABLE3 is $VARIABLE3"

Slightly DRYer, but trickier

. config_file
for var in VARIABLE1 VARIABLE2 VARIABLE3; do
    echo "Content of $var is ${!var}"
done

Answer 5

awk -F\= '{gsub(/"/,"",$2);print "Content of " $1 " is " $2}' <filename>

Just FYI, another pure bash solution

IFS="="
while read -r name value
do
echo "Content of $name is ${value//\"/}"
done < filename

Answer 6

I do in this way

. $PATH_TO_FILE