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Bash script to find comments in file

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# 8  
Old 11-20-2014
Thank you everyone for your help. I want to read in the from from the command line, search for comments, then output to the screen: example ./myscript.bash <comments_script.sh. If no comments are found in the script, then I simply want to output "No comments found."

Here's what I have so far, which prompts me for more info. I know it's a simple exercise for most of you, but for my first month of programming it's a challenge for me.

Code:
n=1
while read -r line
do      if [ "$line" != "${line#*#}" ]
        then
                printf '%d\t%s\n' $n "$line"
        else
                echo "No comments found"
        fi
        n=$((n + 1))
done

# 9  
Old 11-20-2014
Don't tell us it "prompts me for more info"; show us the exact message that bash prints as a prompt.

When I save the following:
Code:
#!/bin/bash
found=0
n=1
while read -r line
do	# Look for comments...
	if [ "$line" != "${line#*#}" ]
	then	# Comment found, print line with line #...
		printf '%d\t%s\n' $n "$line"
		# Note that we found a comment...
		found=1
	fi
	# Increment line # for next line...
	n=$((n + 1))
done
# Print note if no comments found...
if [ ! $found ]
then	echo "No comments found."
fi

in myscript.bash, make it exeutable with:
Code:
chmod +x myscript.bash

and execute it with:
Code:
./myscript.bash < myscript.bash

(which reads itself as a file; not from data typed into the shell on standard input), I get the output:
Code:
1	#!/bin/bash
5	do	# Look for comments...
6	if [ "$line" != "${line#*#}" ]
7	then	# Comment found, print line with line #...
9	# Note that we found a comment...
12	# Increment line # for next line...
15	# Print note if no comments found.

which correctly shows all lines with comments, but has a false positive on line #6. It does not prompt for any more info.

As I said before: "Writing a full parser to find C or shell or some other language's comments accurately in bash is a non-trivial challenge." I'm not going to attempt to weed out the false positives this script will print for you on a forum like this.
This User Gave Thanks to Don Cragun For This Post:
ksmarine1980
# 10  
Old 11-20-2014
That's perfect, Don!

The only line I'm not sure I understand:
if [ "$line" != "${line#*#}" ]

I understand the reference to line from above, and the not equal (!=), but the #*# is confusing. I want to make sure I understand everything I'm doing as well. Thanks again!
# 11  
Old 11-20-2014
Don uses string substitution feature of bash, you can
Code:
man bash

and read all the details

To demonstrate:

Code:
  
$ a="123 abc # qwe"
$ echo ${a#*#}     
qwe
  
$ a="123 abc + qwe"
$ echo ${a#*#}     
 123 abc + qwe

So, when your line does not have '#' the if statement will evaluate it as equal and not go into reporting a comment
This User Gave Thanks to migurus For This Post:
ksmarine1980
# 12  
Old 11-20-2014
Thank you kind sir! And thanks again to all who helped
Last edited by ksmarine1980; 11-20-2014 at 10:39 PM..
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