How to troubleshoot this error right now:

1. In VIM, pick an opening {, [, or ( symbol. The % command jumps between matching { }, [ ], and ( ) pairs. Mismatches will jump to an unexpected location.

2. Install perltidy, run it, and look for oddly indented code blocks.

How to prevent future errors:

1. StackOverflow question 719476 shows how to modify VIM brace/bracket syntax coloring for braces/brackets. (Some versions don t do this by default.)

2. Karl Guertin s AutoClose plugin auto-matches [, (, {, ", symbols when typed.

3. perltidy script reformats perl for readability, which can expose mismatched symbols.

4. User a paid nerd said: "Use perltidy within VIM editor with nmap."

   nmap g mt:%!perltidy<CR> t

5. Use consistent {} matching indentation (general tip, not specific to this perl error).

sub foo {
...
}

or

sub bar
{
...
}

You can use the % command to match braces/brackets/parentheses in vim. So use that to search for unmatched characters.

I constantly use perltidy to reformat my code. When I reformat code that s missing a terminator, further code indents strangely and I can quickly trace upward to locate the problem.

Bonus: I use this mapping to instantly reformat the file and not lose the cursor position:

nmap g mt:%!perltidy<CR> t

Use padre. Click Perl->Find Unmatched Brace. It moves your cursor right to the problem.

I came to this page with the same problem. Using perltidy and vim were of no help, the indenting looked fine after perltidy. I had an extra open brace before a sub keyword for some reason. Padre solved the problem in one-click.

http://padre.perlide.org/

use syntax highlighting, vim almost always get this right, and has a very sophisticated perl syntax highlighting scheme.

:syntax on

It sounds like you may be talking about a teaching situation, in which case teaching good indentation will solve most of these issues.

However, sometimes I m on a server with no niceties like vim and perltidy, and I use a quick n dirty technique to find the syntax error - just add a right-curly at different points in your code until the line number changes, and there s your trouble spot.

If you don t see any missing braces :
Replacing with can help to fix this issue if the file created in windows and trying to use in Linux.

I got this error in a script that appeared to have perfectly matched curly and square braces... except that I had used bash-style syntax which actually commented out the second half of one line (with the second half of a curly brace pair).

The error went away when I changed this line:

$data_len="${#insert_data}";

to this:

$data_len=length($insert_data);

Use regular expression to narrow down where offending code. Example using shell, pcregrep

cat index.pl |pcregrep  [{]{1}[wW^}^{]{90,} 

varying 90 as needed for limiting block length before expecting an ending brace.

As a simple re-statement and combination of @Ether and @Matthew Glidden:

Intent shown like this ( vi command like this )

1. Go to top of file ( 1G )
2. Search for brackets ( /[[({] then press "Enter" )
   • That s "slash" "open square brace" "open square brace" "open round brace" "open curly brace" "close square brace"
   • As a regex, we re searching for a custom character class which is all opening braces.
3. Find end matching bracket ( % )
4. Find starting bracket again ( % )
5. Find next opening bracket ( n )
6. Repeat from 3 until you ve checked all brackets in file.

Works as far back as vi on HP-UX 11.11 (like ~2001).