quote-count: A debugging tool for shell scripts

I've been doing a lot of shell scripting lately with Dash and Bash. Complicated scripts with lots of text handling make debugging difficult, especially when they are being used in sub-shells which obfuscate line numbers in error messages. One of my more common mistakes is an unmatched quote. These can be rather difficult to find so I wrote quote-count, a simple analysis tool that counts quotes in lines.

It just accepts a single filename as a parameter and counts single, double, and back quotes on each line and prints their totals. It prints out a warning if the any of the counts is odd-numbered which may indicate a mismatched quote. It also warns if the line is a comment so you easily ignore those. It isn't brilliant as it doesn't handle escaped newlines, in-line comments, escaped quotes or quotes encapsulated within other quotes. It could be enhanced to handle these cases but it's already saved me a lot of debugging time as is. The output from running it on itself looks like this:

1 Q:0 DQ:0 BQ:0 # COMMENT
2 Q:0 DQ:0 BQ:0 # COMMENT
3 Q:0 DQ:0 BQ:0 # COMMENT
4 Q:0 DQ:0 BQ:0 # COMMENT
5 Q:0 DQ:0 BQ:0 # COMMENT
6 Q:0 DQ:0 BQ:0 # COMMENT
7 Q:0 DQ:0 BQ:0 # COMMENT
8 Q:0 DQ:0 BQ:0
9 Q:0 DQ:8 BQ:0
10 Q:0 DQ:2 BQ:0
11 Q:0 DQ:2 BQ:0
12 Q:0 DQ:2 BQ:0
13 Q:0 DQ:2 BQ:0
14 Q:0 DQ:2 BQ:0
15 Q:0 DQ:0 BQ:0
16 Q:0 DQ:0 BQ:0
17 Q:0 DQ:0 BQ:0
18 Q:0 DQ:0 BQ:0
19 Q:0 DQ:0 BQ:0
20 Q:0 DQ:0 BQ:0
21 Q:0 DQ:2 BQ:0
22 Q:4 DQ:5 BQ:1 # ODD
23 Q:0 DQ:2 BQ:0
24 Q:5 DQ:4 BQ:1 # ODD
25 Q:0 DQ:2 BQ:0
26 Q:5 DQ:3 BQ:2 # ODD
27 Q:0 DQ:2 BQ:0
28 Q:0 DQ:4 BQ:0
29 Q:0 DQ:2 BQ:0
30 Q:0 DQ:2 BQ:0
31 Q:0 DQ:0 BQ:0
32 Q:0 DQ:0 BQ:0
33 Q:0 DQ:0 BQ:0

I've tested it with both Dash and Bash on Ubuntu 9.10 and Mandriva 2010.1 so it should work with most systems.

Another typo I occasionally encounter is escaped whitespace at the end of a line. The intent always is to escape a newline but sometimes in my editing I end up with a space or tab after the backslash. These can easily be found with grep:

grep -E -r -n '\\[[:space:]]+$'<filename>

I wanted to add this check to quote-count v1.0 but found that the "while read" loop removes everything after the trailing backslash. Richard Bos sent me a modified version that included the check as a pre-processor utilizing a simple grep trick. I added it in although it used an array which Dash doesn't support.

UPDATE: v1.2 released and link updated. I found some bugs in v1.1 with the TEW check. I also cleaned up the report output a bit.

Reading through the quote-count report for my larger scripts was tedious so I wrote quote-count-query which compares the original source file with the quote-count report and shows the affected lines with two preceding and following lines for context.