Remove commented lines except one comment using sed

Question

Not very familiar with complex usages of sed, but I have this requirement now. I have a file 1.txt with contents in the following pattern:

sree@amby01:/home/sree : cat 1.txt
SSL
 this first line
#comment line
 second line
# third comment
# line nline
#ApiText
lkjfl
# my line
your line
sree@amby01:/home/sree :

Now, I want to remove the commented lines between the block SSL....#ApiText, but the line #ApiText should not be removed.

The output should look like this:

SSL
this first line
 second line
#ApiText

Its a bash shell. I know how to remove commented lines alone, but not how to remove commented lines except when the comment is following by a certain text. I can use only sed.

Answer 1

There are many ways but one from several can be:

sed '/SSL/,/#ApiText/{//b;/^#/d}' 1.txt

• /SSL/,/#ApiText/ - address range where commands will be executed
• // - for line(s) with previous regexp (SSL or #ApiText - any of found)
• b - go to end of instructions ( mean to do nothing)
• /^#/d - delete(do not print) lines which starts by #