How can I escape special characters that is entered in a function which contains awk command?

To make this problem simple to demonstrate, I made a fake xml file like this.

<abc>
      <spirit:addressBlock>
        <spirit:name>cmn700_registers</spirit:name>
          <def>
          </def>
      </spirit:addressBlock>
</abc>

And I want to print lines containing pattern <spirit:name> inside a block of lines, the block begining with the pattern <spirit:addressBlock> and ending with </spirit:addressBlock>. I defined a function in .bash_aliase like this.

function SearchPatInBlk {
awk "/$1/{inblk=1} inblk==1&&/$2/{inblk=0} inblk==1&&/$3/{print \$0}" $4
}

So the first argument and second argument is the block start and end pattern, third argument is the pattern I want to print the line with and the fourth argument is the xml filename. And then I gave this command at the bash shell.

SearchPatInBlk <spirit:addressBlock> </spirit:addressBlock> <spirit:name> ../../ab21/ab21_cmn700_new10_clst/build/ab21_cmn700/logical/cmn700/ipxact/cmn700_ab21.xml

Of course this gives me an error.

bash: syntax error near unexpected token `<'

So I tried putting some escape characters (\) before <,>,/ but it doesn't work. How should I do it?

Solution

Using a true XML parser would be better than a general purpose text processor like awk. But if you absolutely need awk there are several things to fix.

Quote your pattern strings.
Escape regex operators in your pattern strings.
Pass your pattern strings to awk as awk variables, not as parts of the awk script.
Use the regex,regex awk range pattern.

Optionally you could also use more accurate regex and, if your awk is GNU awk, mark the patterns as regex constants (@/.../):

function SearchPatInBlk {
  awk -v v1="$1" -v v2="$2" -v v3="$3" 'v1,v2 {if($0 ~ v3) print}' "$4"
}

SearchPatInBlk '@/^[[:space:]]*[<]spirit:addressBlock[>][[:space:]]*$/' \
  '@/^[[:space:]]*[<][/]spirit:addressBlock[>][[:space:]]*$/' \
  '@/[<]spirit:name[>]' file