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deleting the lines at the end of the file.

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Top Forums Shell Programming and Scripting deleting the lines at the end of the file.
# 1  
Old 09-09-2010
Hammer & Screwdriver deleting the lines at the end of the file.
I have a text file with two coulmn
first column is just used in to show the line number, these line number are not there in the real file.

I want to delete the line 16(in this file) here, even tough there is no data inside it . this empty line is causing me a problem by throwing me garbage value when i input this stream in my c++ program.

Code:
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

i tried using
Code:
1:  sed -i '/^$/d' file > newfile
2:  sed '/./!d'     file > newfile
3:  sed -e :a -e '/^\n*$/{$d;N;ba' -e '}' file

all these three commands just delete blank line after line 16. but i want my output in the new file to be just

Code:
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

and not as the first one

how should i solve this.
# 2  
Old 09-09-2010
Hey bud, The line no. 16 is not deleted because it is not empty!
Now that you have managed to delete the 17th totally empty line, delete line number 16 (containing '16' at the beginning of the line) like this:

PHP Code:
sed '/^16/d' file > newfile 
What it does is it deletes the line 'starting with' 16.

Let me know if that helped

(FYI - verified this on HP-UX)
# 3  
Old 09-09-2010
If you want to remove all lines after the 15th line this should work:
Code:
awk 'NR < 16' file > newfile

or have I missed something?
# 4  
Old 09-09-2010
I'm sorry, but the code dosent work. its not removing my last line. i still get the o/p as i got in first case

---------- Post updated at 11:22 AM ---------- Previous update was at 11:18 AM ----------

@ Franklin, the number changes everytime.

actually currently what i am doing is
1: opening the txt file, then going to the
Code:
15  266.201    1.91486e-07 ------> doing a backspace here so that it deletes the last empty line 16
16

# 5  
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..
# 6  
Old 09-09-2010
Quote:
Originally Posted by shashi792
@ Franklin, the number changes everytime.

actually currently what i am doing is
1: opening the txt file, then going to the
Code:
15  266.201    1.91486e-07 ------> doing a backspace here so that it deletes the last empty line 16
16

Are you trying to delete the last newline character?
# 7  
Old 09-10-2010
@Franklin,
I did not understand your question.

I have these problem when i am streaming my text file to a C++ array.

rite now i am manually going to the line 15 and at the end of the line i'm using delete so that the last empty line gets deleted .
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