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Full Discussion: Remove blank lines using cat command
Top Forums UNIX for Dummies Questions & Answers Remove blank lines using cat command Post 302906687 by bakunin on Monday 23rd of June 2014 03:28:00 AM
Old 06-23-2014
Quote:
Originally Posted by mushfiks1
how i remove empty or blank files using cat command.
hmm... How can i fly to the moon using an invalidated credit card and a screwdriver?

The short answer is: you can't because the tool you want to use (in this case "cat") isn't designed to do what you want. (Actually "cat" is for conCATenating files.)

The long answer is: you might want to rephrase/rethink your question and get a better answer. But it won't even stop at that. Rethinking your question will put you into a state of mind where the solution will come more easily to you, not only because you will get better answers but because you may find it out yourself. Defining correctly (rigidly and meticulously) the goal is - more often than not - already three quarters of the solution.

There are several tools doing perfectly what you want, Unix is rich in all sorts of text filters: sed, awk, sort, and even the native shell can do what you want. You already got a solution in awk, so here is one in sed:

Code:
sed '/^$/d' /path/to/input > /path/to/output

I hope this helps.

bakunin
 

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LEARN ABOUT SUSE

quiz

QUIZ(6) 							 BSD Games Manual							   QUIZ(6)

NAME

     quiz -- random knowledge tests

SYNOPSIS

     quiz [-t] [-i file] [question answer]

DESCRIPTION

     The quiz utility tests your knowledge of random facts.  It has a database of subjects from which you can choose.  With no arguments, quiz
     displays the list of available subjects.

     The options are as follows:

     -t      Use tutorial mode, in which questions are repeated later if you didn't get them right the first time, and new questions are presented
	     less frequently to help you learn the older ones.

     -i      Specify an alternative index file.

     Subjects are divided into categories.  You can pick any two categories from the same subject.  quiz will ask questions from the first cate-
     gory and it expects answers from the second category.  For example, the command ``quiz victim killer'' asks questions which are the names of
     victims, and expects you to answer with the cause of their untimely demise, whereas the command ``quiz killer victim'' works the other way
     around.

     If you get the answer wrong, quiz lets you try again.  To see the right answer, enter a blank line.

   Index and Data File Syntax
     The index and data files have a similar syntax.  Lines in them consist of several categories separated by colons.	The categories are regular
     expressions formed using the following meta-characters:

	   pat|pat  alternative patterns
	   {pat}    optional pattern
	   [pat]    delimiters, as in pat[pat|pat]pat

     In an index file, each line represents a subject.	The first category in each subject is the pathname of the data file for the subject.  The
     remaining categories are regular expressions for the titles of each category in the subject.

     In data files, each line represents a question/answer set.  Each category is the information for the question/answer for that category.

     The backslash character (``'') is used to quote syntactically significant characters, or at the end of a line to signify that a continuation
     line follows.

     If either a question or its answer is empty, quiz will refrain from asking it.

FILES

     /usr/share/games/quiz  The default index and data files.

BUGS

     quiz is pretty cynical about certain subjects.

BSD
								   May 31, 1993 							       BSD
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