:begin
$!N
s/[#;]([^[:space:]]|[[:blank:]])*([^\\[:space:]]|[[:blank:]])(\n)/\3/
s/[#;]([^[:space:]]|[[:blank:]])*(\\)(\n)/\2\3/
$s/[#;]([^[:space:]]|[[:blank:]])*$//
/(\\\n|\n[[:blank:]]{4})/ {
  s/[[:blank:]]*(\\\n|\n[[:blank:]]{4})[[:blank:]]*/ /
  t begin
}
/^[[:blank:]]*\n/ D
/\n[[:blank:]]*$/ {
  s/\n[[:blank:]]*$//
  t begin
}
/^\[([^[:space:]]|[[:blank:]])*\]/! D
s/\[[[:blank:]]*//
s/[[:blank:]]*\]([^[:space:]]|[[:blank:]])*//
P
D

# -*- mode: conf-mode ; -*- \
#;
#; sample .ini file
#;
#;

[tako]
param_a=(1 # 2 3 \
4 5 ### 6 7?
? ? 8 9 # 10
? ? )

a=b # kani \
# kani \


[kani]
param_a=1
param_b=2

[uni]
param_a=3
param_b=4

[wani]
param_a=5
param_b=6

[hebi]
param_a=9
param_b=10

output example:

% sed -nE -f list_section.sed sample.ini
tako
kani
uni
wani
hebi

:begin
$!N
# Erase comment strings
s/[#;]([^[:space:]]|[[:blank:]])*([^\\[:space:]]|[[:blank:]])(\n)/\3/
s/[#;]([^[:space:]]|[[:blank:]])*(\\)(\n)/\2\3/
$s/[#;]([^[:space:]]|[[:blank:]])*$//
# Concatenate continuation lines
/(\\\n|\n[[:blank:]]{4})/ {
? s/[[:blank:]]*(\\\n|\n[[:blank:]]{4})[[:blank:]]*/ /
? t begin
}
# Erase blank lines
/^[[:blank:]]*\n/ D
/\n[[:blank:]]*$/ {
? s/\n[[:blank:]]*$//
? t begin
}
# Check section headline and store section name to holdspace
/^([^[:space:]]|[[:blank:]])*\[([^[:space:]]|[[:blank:]])*\]/ {
h
x
s/^([^[:space:]]|[[:blank:]])*\[(([^[:space:]]|[[:blank:]])*)\].*$/\2/g
s/^[[:blank:]]*//g
s/[[:blank:]]$//g
x
D
}
# Skip line if current section is not interested one
x
/^wani$/! {?
? x
? D
}
x
# Print if it is proper parameter definition?
/^(([^[:space:]=]|[[:blank:]])*)=(([^[:space:]]|[[:blank:]])*)/ {
? s/^[[:blank:]]*/local /
? s/[[:blank:]]*=[[:blank:]]*/=/
? s/(([^[:space:]]|[[:blank:]])*)[[:blank:]]*(\n)/\1;\3/
? P
}
D

# Initialine the hold space: (Single empty line at the beginning)
1 { H ; x ;?
? # Change the expression for the defalut section name and/or variable prefix, here.
? s/^([^[:space:]]|[[:blank:]])*(\n)([^[:space:]]|[[:blank:]])*$/global\2global_/g
? x
}
:begin
$!N
# Erase comment strings
s/[#;]([^[:space:]]|[[:blank:]])*([^\\[:space:]]|[[:blank:]])(\n)/\3/
s/[#;]([^[:space:]]|[[:blank:]])*(\\)(\n)/\2\3/
$s/[#;]([^[:space:]]|[[:blank:]])*$//
# Concatenate continuation lines
/(\\\n|\n[[:blank:]]{4})/ {
? s/[[:blank:]]*(\\\n|\n[[:blank:]]{4})[[:blank:]]*/ / ; t begin
}
# Erase blank lines
/^[[:blank:]]*\n/ D
/\n[[:blank:]]*$/ {
? s/\n[[:blank:]]*$// ; t begin
}
# Check section headline and store section name to holdspace
/^([^[:space:]]|[[:blank:]])*\[([^[:space:]]|[[:blank:]])*\]/ {
? # Remove blackets and extra spaces at first line
? s/^([^[:space:]]|[[:blank:]])*\[(([^[:space:]]|[[:blank:]])*)\](([^[:space:]]|[[:blank:]])*)(\n)/\2\6/g
? s/^[[:blank:]]*//g; s/[[:blank:]]*(\n)/\1/g
? # Store the section name to the hold space, and format stored one for shell variable for the hold space
? h
? x
? s/(\n)([^[:space:]]|[[:blank:]])*$//
? s/([^[:alnum:]_]|$)/_/g
? x
? # Append the section name to the hold space.
? H
? # Remove unused line of the hold space and rearrange the remaining lines.
? x
? s/(([^[:space:]]|[[:blank:]])*)(\n)(([^[:space:]]|[[:blank:]])*)(\n)(([^[:space:]]|[[:blank:]])*)$/\4\3\1/
? x
? D
}
# Skip line if current section is not interested one
x
/^(wani|uni)(\n)/! { x ; D ; }
x
# Print if it is proper parameter definition?
/^(([^[:space:]=]|[[:blank:]])*)=(([^[:space:]]|[[:blank:]])*)/ {
? # Store current patern space text at the end of the hold space
? H

? # Build shell script variable name and store it at the end of the hold space
? s/(([^[:space:]=]|[[:blank:]])*)=.*$/\1/g
? s/^[[:blank:]]*//
? s/[[:blank:]]*$//
? s/[^[:alnum:]_]/_/g
? # If further rename of the variable name is necessary, put here.

? # Store variable name at the end of the hold space
? H

? # Build parameter variable value and keep it at pattern space
? # At first, Resore the current line text from hold space
? g
? # Remove unused lines.
? s/^(([^[:space:]]|[[:blank:]])*\n){2}//
? s/(\n([^[:space:]]|[[:blank:]])*){2}$//
? # Remove the text other than the parameter value
? s/^([^[:space:]=]|[[:blank:]])*=//g
? # If further formatting of the value is necessary, put here.

? # Append hold space stored date into pattern space
? G
? # Remove unused lines from the pattern space
? s/^(([^[:space:]]|[[:blank:]])*\n)(([^[:space:]]|[[:blank:]])*\n)(([^[:space:]]|[[:blank:]])*\n)(([^[:space:]]|[[:blank:]])*\n)(([^[:space:]]|[[:blank:]])*\n)/\1\5\9/
? # Rearrance the order of line in the pattern space, it is nessacery because only \1 ...\9 is avaiable
? s/^(([^[:space:]]|[[:blank:]])*\n)(([^[:space:]]|[[:blank:]])*\n)(([^[:space:]]|[[:blank:]])*)(\n)(([^[:space:]]|[[:blank:]])*)$/\1\3\8\7\5/

? # Format the output in the first line of the pattern space, and?
? # Restore the next line at the second line of the pattern space
? s/^(([^[:space:]]|[[:blank:]])*)(\n)(([^[:space:]]|[[:blank:]])*)(\n)(([^[:space:]]|[[:blank:]])*)(\n([^[:space:]]|[[:blank:]])*)$/local \4\7=\1;\9/

? # Clean up hold space
? x
? s/(\n([^[:space:]]|[[:blank:]])*){3}$//
? x
? P
}
D

[Usage] % parse_ini.sh -list ? ? file [files ...]
? ? ? ? % parse_ini.sh [options] file [files ...]

[Options]
? ? -l,--list ? ? ? ? ? ? ? ? ? ? ? : List sections?
? ? -S,--sec-select ? ? ? name ? ? ?: Section name to select
? ? -T,--sec-select-regex expr ? ? ?: Section reg. expr. to select
? ? -V,--variable-select name ? ? ? : variable name to select
? ? -W,--variable-select-regex expr : variable reg. expr. to select
? ? -L,--local ? ? ? ? ? ? ? ? ? ? ?: Definition as local variables (B-sh)
? ? -e,--env ? ? ? ? ? ? ? ? ? ? ? ?: Definition as enviromnental variables
? ? -q,--quot ? ? ? ? ? ? ? ? ? ? ? : Definition by quoting with double/single-quotation.
? ? -c,--csh,--tcsh ? ? ? ? ? ? ? ? : Output for csh statement (default: B-sh)
? ? -b,--bsh,--bash ? ? ? ? ? ? ? ? : Output for csh statement (default)
? ? -s,--sec-prefix ? ? ? ? ? ? ? ? : add prefix: 'sectionname_' to variable names.?
? ? -v,--verbose ? ? ? ? ? ? ? ? ? ?: Verbose messages?
? ? -h,--help ? ? ? ? ? ? ? ? ? ? ? : Show Help (this message)