sed one-liners to deal with .ini / .conf files

ini.sed

#  List all [sections] of a .INI file

sed -n 's/^[ \t]*\[\(.*\)\].*/\1/p'

#  Read KEY from [SECTION]

sed -n '/^[ \t]*\[SECTION\]/,/\[/s/^[ \t]*KEY[ \t]*=[ \t]*//p'

#  Read all values from SECTION in a clean KEY=VALUE form

sed -n '/^[ \t]*\[SECTION\]/,/\[/s/^[ \t]*\([^#; \t][^ \t=]*\).*=[ \t]*\(.*\)/\1=\2/p'

# examples:

sed -n 's/^[ \t]*\[\(.*\)\].*/\1/p' /etc/samba/smb.conf
sed -n '/^[ \t]*\[global\]/,/\[/s/^[ \t]*workgroup[ \t]*=[ \t]*//p' /etc/samba/smb.conf
sed -n '/^[ \t]*\[global\]/,/\[/s/^[ \t]*\([^#; \t][^ \t=]*\).*=[ \t]*\(.*\)/\1=\2/p' /etc/samba/smb.conf

Thank you for this gist. As an expansion to what you've already done here's a bash function for updating a key value pair within a specific section. If the key/value doesn't already exist in the section the script will append it to the end of the section. If the section doesn't exist, the script will create it at the end and add the key/value to it.

# escapes all regex meta characters in a string using Perl's "quotemeta" function
awkconfig_quotemeta(){
  local PERL_QUOTEMETA_SCRIPT="print quotemeta(\$ARGV[0]);"
  perl -e "${PERL_QUOTEMETA_SCRIPT}" "${1:-/dev/stdin}"
}

awkconfig_update_value(){
  local section="$1"
  local key="$2"
  local value="$3"
  awk -v RS="(^|\n)[:blank:]*\\\\[" -v setFound=0 -v sec="$section"\
   -v kv="$key=$value" -v secPat="$(awkconfig_quotemeta "$section")" -v subPat="$(awkconfig_quotemeta "$key")"\
   '$1~"^[[:blank:]\[]*" secPat "[:blank:]*\]"{ \
        s = sub("[:blank:]*" subPat "[:blank:]*=[^#^;^\n]*", kv);\
        $0 = $0 ((0 == s)? "\n" kv "\n" : ""); # adding kv to $0;\
        secFound=1;\
    }\
    $1~"^[^;^#^\n^=]*\]"{\
      $0 = "[" $0; # adding the record separator "[" back in\
    }\
    {print $0}\
    END{ \
      if (secFound == 0){\
        # adding a new section if we didnt see it yet\
        print "#\n";\
        print "[" sec "]\n";\
        print kv;\
      }\
    }' "${4:-/dev/stdin}" | awk NF
    # "awk NF" removes blank lines https://stackoverflow.com/questions/10347653/awk-remove-blank-lines
    # you could also use "sed '/^[[:space:]]*$/d'" instead of "awk NF"
} # end awkconfig_update_value```