[bash] How do I grab an INI value within a shell script?

Just finished writing my own parser. I tried to use various parser found here, none seems to work with both ksh93 (AIX) and bash (Linux).

It's old programming style - parsing line by line. Pretty fast since it used few external commands. A bit slower because of all the eval required for dynamic name of the array.

The ini support 3 special syntaxs:

  • includefile=ini file --> Load an additionnal ini file. Useful for splitting ini in multiple files, or re-use some piece of configuration
  • includedir=directory --> Same as includefile, but include a complete directory
  • includesection=section --> Copy an existing section to the current section.

I used all thoses syntax to have pretty complex, re-usable ini file. Useful to install products when installing a new OS - we do that a lot.

Values can be accessed with ${ini[$section.$item]}. The array MUST be defined before calling this.

Have fun. Hope it's useful for someone else!

function Show_Debug {
    [[ $DEBUG = YES ]] && echo "DEBUG $@"
    }

function Fatal {
    echo "$@. Script aborted"
    exit 2
    }
#-------------------------------------------------------------------------------
# This function load an ini file in the array "ini"
# The "ini" array must be defined in the calling program (typeset -A ini)
#
# It could be any array name, the default array name is "ini".
#
# There is heavy usage of "eval" since ksh and bash do not support
# reference variable. The name of the ini is passed as variable, and must
# be "eval" at run-time to work. Very specific syntax was used and must be
# understood before making any modifications.
#
# It complexify greatly the program, but add flexibility.
#-------------------------------------------------------------------------------

function Load_Ini {
    Show_Debug "$0($@)"
    typeset ini_file="$1"
# Name of the array to fill. By default, it's "ini"
    typeset ini_array_name="${2:-ini}"
    typeset section variable value line my_section file subsection value_array include_directory all_index index sections pre_parse
    typeset LF="
"
    if [[ ! -s $ini_file ]]; then
        Fatal "The ini file is empty or absent in $0 [$ini_file]"
    fi

    include_directory=$(dirname $ini_file)
    include_directory=${include_directory:-$(pwd)}

    Show_Debug "include_directory=$include_directory"

    section=""
# Since this code support both bash and ksh93, you cannot use
# the syntax "echo xyz|while read line". bash doesn't work like
# that.
# It forces the use of "<<<", introduced in bash and ksh93.

    Show_Debug "Reading file $ini_file and putting the results in array $ini_array_name"
    pre_parse="$(sed 's/^ *//g;s/#.*//g;s/ *$//g' <$ini_file | egrep -v '^$')"
    while read line; do
        if [[ ${line:0:1} = "[" ]]; then # Is the line starting with "["?
# Replace [section_name] to section_name by removing the first and last character
            section="${line:1}"
            section="${section%\]}"
            eval "sections=\${$ini_array_name[sections_list]}"
            sections="$sections${sections:+ }$section"
            eval "$ini_array_name[sections_list]=\"$sections\""
            Show_Debug "$ini_array_name[sections_list]=\"$sections\""
            eval "$ini_array_name[$section.exist]=YES"
            Show_Debug "$ini_array_name[$section.exist]='YES'"
        else
            variable=${line%%=*}   # content before the =
            value=${line#*=}       # content after the =

            if [[ $variable = includefile ]]; then
# Include a single file
                Load_Ini "$include_directory/$value" "$ini_array_name"
                continue
            elif [[ $variable = includedir ]]; then
# Include a directory
# If the value doesn't start with a /, add the calculated include_directory
                if [[ $value != /* ]]; then
                    value="$include_directory/$value"
                fi
# go thru each file
                for file in $(ls $value/*.ini 2>/dev/null); do
                    if [[ $file != *.ini ]]; then continue; fi
# Load a single file
                    Load_Ini "$file" "$ini_array_name"
                done
                continue
            elif [[ $variable = includesection ]]; then
# Copy an existing section into the current section
                eval "all_index=\"\${!$ini_array_name[@]}\""
# It's not necessarily fast. Need to go thru all the array
                for index in $all_index; do
# Only if it is the requested section
                    if [[ $index = $value.* ]]; then
# Evaluate the subsection [section.subsection] --> subsection
                        subsection=${index#*.}
# Get the current value (source section)
                        eval "value_array=\"\${$ini_array_name[$index]}\""
# Assign the value to the current section
# The $value_array must be resolved on the second pass of the eval, so make sure the
# first pass doesn't resolve it (\$value_array instead of $value_array).
# It must be evaluated on the second pass in case there is special character like $1,
# or ' or " in it (code).
                        eval "$ini_array_name[$section.$subsection]=\"\$value_array\""
                        Show_Debug "$ini_array_name[$section.$subsection]=\"$value_array\""
                    fi
                done
            fi

# Add the value to the array
            eval "current_value=\"\${$ini_array_name[$section.$variable]}\""
# If there's already something for this field, add it with the current
# content separated by a LF (line_feed)
            new_value="$current_value${current_value:+$LF}$value"
# Assign the content
# The $new_value must be resolved on the second pass of the eval, so make sure the
# first pass doesn't resolve it (\$new_value instead of $new_value).
# It must be evaluated on the second pass in case there is special character like $1,
# or ' or " in it (code).
            eval "$ini_array_name[$section.$variable]=\"\$new_value\""
            Show_Debug "$ini_array_name[$section.$variable]=\"$new_value\""
        fi
    done  <<< "$pre_parse"
    Show_Debug "exit $0($@)\n"
    }

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