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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 LINUX

git-stripspace

GIT-STRIPSPACE(1)						    Git Manual							 GIT-STRIPSPACE(1)

NAME

       git-stripspace - Remove unnecessary whitespace

SYNOPSIS

       git stripspace [-s | --strip-comments] < input

DESCRIPTION

       Clean the input in the manner used by Git for text such as commit messages, notes, tags and branch descriptions.

       With no arguments, this will:

       o   remove trailing whitespace from all lines

       o   collapse multiple consecutive empty lines into one empty line

       o   remove empty lines from the beginning and end of the input

       o   add a missing 
 to the last line if necessary.

       In the case where the input consists entirely of whitespace characters, no output will be produced.

       NOTE: This is intended for cleaning metadata, prefer the --whitespace=fix mode of git-apply(1) for correcting whitespace of patches or
       files in the repository.

OPTIONS

       -s, --strip-comments
	   Skip and remove all lines starting with comment character (default #).

       -c, --comment-lines
	   Prepend comment character and blank to each line. Lines will automatically be terminated with a newline. On empty lines, only the
	   comment character will be prepended.

EXAMPLES

       Given the following noisy input with $ indicating the end of a line:

	   |A brief introduction   $
	   |   $
	   |$
	   |A new paragraph$
	   |# with a commented-out line    $
	   |explaining lots of stuff.$
	   |$
	   |# An old paragraph, also commented-out. $
	   |	  $
	   |The end.$
	   |  $

       Use git stripspace with no arguments to obtain:

	   |A brief introduction$
	   |$
	   |A new paragraph$
	   |# with a commented-out line$
	   |explaining lots of stuff.$
	   |$
	   |# An old paragraph, also commented-out.$
	   |$
	   |The end.$

       Use git stripspace --strip-comments to obtain:

	   |A brief introduction$
	   |$
	   |A new paragraph$
	   |explaining lots of stuff.$
	   |$
	   |The end.$

GIT

       Part of the git(1) suite

Git 1.8.5.3							    01/14/2014							 GIT-STRIPSPACE(1)
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