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Full Discussion: deleting the lines at the end of the file.
Top Forums Shell Programming and Scripting deleting the lines at the end of the file. Post 302452179 by durden_tyler on Thursday 9th of September 2010 01:14:24 PM
Old 09-09-2010
Code:
$
$
$ # Show data without line numbers on the left
$ cat f13
0              2.14014e-07
13.214      1.00771e-06
13.947      3.76252e-05
13.958      5.2692e-06
13.966     4.87701e-06
14.065     3.81149e-06
14.076     3.65411e-06
14.29       9.82566e-07
17.899     6.10872e-07
19.757     7.14666e-07
200.947    1.78718e-07
226.555    1.34066e-07
231.43     1.35589e-07
231.8       9.41089e-08
266.201    1.91486e-07
 
$
$ # Show data *with* lines numbers on the left
$ cat -n f13
     1  0              2.14014e-07
     2  13.214      1.00771e-06
     3  13.947      3.76252e-05
     4  13.958      5.2692e-06
     5  13.966     4.87701e-06
     6  14.065     3.81149e-06
     7  14.076     3.65411e-06
     8  14.29       9.82566e-07
     9  17.899     6.10872e-07
    10  19.757     7.14666e-07
    11  200.947    1.78718e-07
    12  226.555    1.34066e-07
    13  231.43     1.35589e-07
    14  231.8       9.41089e-08
    15  266.201    1.91486e-07
    16
$
$ # Remove the blank line at the end. Assume that the blank line *may have* whitespaces.
$ # Perform an inline replacement in the data file.
$
$ perl -pi.bak -e 's/^\s*$//' f13
$
$ # Check the modified data file.
$ cat -n f13
     1  0              2.14014e-07
     2  13.214      1.00771e-06
     3  13.947      3.76252e-05
     4  13.958      5.2692e-06
     5  13.966     4.87701e-06
     6  14.065     3.81149e-06
     7  14.076     3.65411e-06
     8  14.29       9.82566e-07
     9  17.899     6.10872e-07
    10  19.757     7.14666e-07
    11  200.947    1.78718e-07
    12  226.555    1.34066e-07
    13  231.43     1.35589e-07
    14  231.8       9.41089e-08
    15  266.201    1.91486e-07
$
$ # Check the backup data file generated by the Perl one-liner.
$ cat -n f13.bak
     1  0              2.14014e-07
     2  13.214      1.00771e-06
     3  13.947      3.76252e-05
     4  13.958      5.2692e-06
     5  13.966     4.87701e-06
     6  14.065     3.81149e-06
     7  14.076     3.65411e-06
     8  14.29       9.82566e-07
     9  17.899     6.10872e-07
    10  19.757     7.14666e-07
    11  200.947    1.78718e-07
    12  226.555    1.34066e-07
    13  231.43     1.35589e-07
    14  231.8       9.41089e-08
    15  266.201    1.91486e-07
    16
$
$
$

This should work if:

(a) there is more than one blank line at the end of the file => the one-liner removes all those blank lines at eof
(b) there is one or more than one blank line before the end of the file => the one-liner removes all those blank lines wherever they are before eof
(c) the lines refered to in (a) and (b) have zero or more whitespaces

tyler_durden
Last edited by durden_tyler; 09-09-2010 at 02:19 PM..
 

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LEARN ABOUT SUSE

arithmetic

ARITHMETIC(6)							 BSD Games Manual						     ARITHMETIC(6)

NAME

     arithmetic -- quiz on simple arithmetic

SYNOPSIS

     arithmetic [-o +-x/] [-r range]

DESCRIPTION

     arithmetic asks you to solve problems in simple arithmetic.  Each question must be answered correctly before going on to the next.  After
     every 20 problems, it prints the score so far and the time taken.	You can quit at any time by typing the interrupt or end-of-file character.

     The options are as follows:

     -o      By default, arithmetic asks questions on addition of numbers from 0 to 10, and corresponding subtraction.	By supplying one or more
	     of the characters +-x/, you can ask for problems in addition, subtraction, multiplication, and division, respectively.  If you give
	     one of these characters more than once, that kind of problem will be asked correspondingly more often.

     -r      If a range is supplied, arithmetic selects the numbers in its problems in the following way.  For addition and multiplication, the
	     numbers to be added or multiplied are between 0 and range, inclusive.  For subtraction and division, both the required result and the
	     number to divide by or subtract will be between 0 and range.  (Of course, arithmetic will not ask you to divide by 0.)  The default
	     is 10.

     When you get a problem wrong, arithmetic will remember the numbers involved, and will tend to select those numbers more often than others, in
     problems of the same sort.  Eventually it will forgive and forget.

     arithmetic cannot be persuaded to tell you the right answer.  You must work it out for yourself.

DIAGNOSTICS

     ``What?'' if you get a question wrong.  ``Right!'' if you get it right.  ``Please type a number.'' if arithmetic doesn't understand what you
     typed.

SEE ALSO

     bc(1), dc(1)

BSD
								   May 31, 1993 							       BSD
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