Getting a text file rid of all superfluous blank lines

[Tim]

Tim:

>> I used to know of something that did that (something with various
>> different reformatting options for massaging text files), but I can't
>> think what it was.  Quickly looking at the man file for the cat program,
>> you could do something like:
>>
>> cat --squeeze-blank inputfilename -> outputfilename

Paul Smith:
> Thanks, Tim and Paul. Paul's method does not mysteriously work:
> 
> $ more file1.txt
> word1
> 
> 
> 
> word2
> 
> word3
> $ more -s file1.txt > file2.txt
> $ more file2.txt
> word1
> 
> 
> 
> word2
> 
> word3

Hmm, seems to work for me.  Both with the "less" and "more" programs, as
well as the "cat" program.

> Tim's way works partially, i.e., many blank lines are in effect
> erased, but some remain. I suspect that the left blank lines are not
> blank lines although they look like blank lines. Can one go further
> with deleting the left "false" blank lines?

In what way do they remain?  Can you provide an actual example?  (Rather
than an explanation of what's happening.)

What I see is that all consecutive blank lines are replaced by a single
blank line, on the file I tried it with. 

e.g. Tested on /etc/selinux/targeted/contexts/files/file_contexts

If you want to remove all blank lines, then perhaps you could use grep.

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