How To Use sed To Remove Text Between '/*'?


 
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# 8  
The current sed script does not allow a * character in comments.
Code:
If x=1 then /* this is an if statement */
/* new *line* added */ echo "hello" /* 2nd comment */;

---------- Post updated at 03:34 AM ---------- Previous update was at 03:28 AM ----------

But
Code:
sed 's|/\*.*\*/||g'

is even worse, because of the "greedy" .*
# 9  
I noticed the same thing. But I didn't want to be too much of a stickler. Thank you for pointing out the defect. /* */ comments are problematic to deal with.
# 10  
Quote:
Originally Posted by MadeInGermany
The current sed script does not allow a * character in comments.
Code:
If x=1 then /* this is an if statement */
/* new *line* added */ echo "hello" /* 2nd comment */;

---------- Post updated at 03:34 AM ---------- Previous update was at 03:28 AM ----------

But
Code:
sed 's|/\*.*\*/||g'

is even worse, because of the "greedy" .*
I don't know to which script you're referring when you say "current sed script". The OP's sed doesn't handle comments at all. Mine does and it allows * in the comment.

You are correct in that the greedy .* will cause problems with multiple comment closing sequences, */, on one line. Thank you for pointing that out, since I neglected to mention it. However, your two comments on a line scenario is extremely unlikely. More likely, I suspect, would be a collision with a string literal.

As I said in my first post, it works with the sample data and, if anything more complicated is needed, perhaps a tool that understands the language should be used. A possible workaround would disallow the * in comments by changing .* to [^*]*. A better solution is to use a tool which supports non-greedy quantifiers, such as perl's .*?.

Even if non-greedy quantifiers are used, the solution is still incomplete even for the simple, single-comment on a single line scenario: a string literal which looks like a comment would be nuked.

Regards,
Alister

---------- Post updated at 05:12 AM ---------- Previous update was at 05:10 AM ----------

Quote:
Originally Posted by hanson44
I noticed the same thing. But I didn't want to be too much of a stickler. Thank you for pointing out the defect. /* */ comments are problematic to deal with.
Let your inner stickler loose. Smilie

Last edited by alister; 03-21-2013 at 07:23 AM..
# 11  
Yes, you are probably right, a tool that understands the language is needed.

Code:
$ cat temp.x
Before /* with ** in middle */ After /* Another comment */
Before /* with ** in middle */ After
Before /* with / in middle */ After /* Another comment */
Before /* with / in middle */ After
Before /* nothing weird in middle */ After
Before /* nothing weird in middle */ After /* Another comment */

$ cpp temp.x | grep -v "^#"
Before After
Before After
Before After
Before After
Before After
Before After

Of course, cpp expands macros, so that's a flaw. But at least cpp handles comments perfectly, which is what the original poster wanted.
 

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