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How to delete all lines with less then 32 characters from a textfile?

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Top Forums Shell Programming and Scripting How to delete all lines with less then 32 characters from a textfile?
# 8  
Old 02-25-2010
@anbu23 and kcoder24:

heheh. nicely done.

Quote:
Originally Posted by kcoder24
My AWK version

Code:
'/.{32,}/'

The AWK implementation on the machine in front of me doesn't support brace intervals, but I assume you can shorten that just a bit more to:
Code:
'/.{32}/'

Smilie

Cheers.
Last edited by alister; 02-25-2010 at 03:09 PM..
# 9  
Old 02-25-2010
We can also remove the lines which are having less than 32 characters in a file by using the following command.

sed -ir '/^.{0,31}$/d' <inputfilename>
# 10  
Old 02-25-2010
Try:

Code:
sed "/^.\{0,31\}$/d" file

EDIT: Just noticed that the above poster beat me to that answer. Oh, well, it was a good exercise.
Last edited by Ultrix; 02-26-2010 at 12:15 AM..
# 11  
Old 02-26-2010
Code:
use strict; 
use warnings;  
open FH,"file"; #this is your input file
open RFH, "> output"; #this will be the output file which will have the lines from the input file longer than 32 characters 

while ( <FH> )  #reading the data from the file
{     
           if ( length $_ > 32 ) #if the line length is greater than 32    
           {         
                   print RFH $_; #writing to the output file     
           } 
}

This is a Perl script.
The file will contain the input data.
After executing the above code the output file will contain the lines which are all having length greater than 32 characters.
Last edited by thillai_selvan; 03-09-2010 at 01:07 AM..
# 12  
Old 02-26-2010
BTW, what is the practical value of what you're trying to do? I really want to know, because I just wrote a shell script that does what you described, only way better, and I'm wondering how I can use it.

---------- Post updated 02-26-10 at 12:57 AM ---------- Previous update was 02-25-10 at 11:54 PM ----------
Quote:
Originally Posted by thillai_selvan
Code:
 use strict; 
use warnings;  
 open FH,"file"; #this is your input script 
my @array = ; #reading the file content in the input file 
open RFH,"> output"; #this will be the output file which will have the lines from the input file longer than 32 characters foreach ( @array ) 
{     
           if ( length $_ > 32 ) #if the line length is greater than 32    
           {         
                   print RFH $_; #writing to the output file     
           } 
}

This is a Perl script.
The file will contain the input data.
After executing the above code the output file will contain the lines which are all having length greater than 32 characters.
Why use an 11 line Perl script when you can use a 1 line shell script? I tested my method and it works perfectly. I also modified it so that it takes an arbitrary range of line lengths, as well as allowing the user to decide whether to write to the file:
Code:
#!/bin/bash
# Deletes lines of a certain range length from a file.
# Writing the result back to the file is optional.

write="no";
for opt in $*
do
    case $opt in
        -w ) write="yes";
             shift;;
        -* ) shift;;
        *  );;
    esac
done
if [ $write == "yes" ]
then
    sed -e "/^.\{$1,$2\}$/d" $3 > tempfile.txt;
    cat tempfile.txt > $3;
    rm tempfile.txt;
else
    sed -e "/^.\{$1,$2\}$/d" $3;
fi

# 13  
Old 02-26-2010
I answered this for the actual poster. Not indented to point to your script.
Perl is also an efficient script. Thats why I wanted to guide the questioner to get fame on my views
# 14  
Old 02-26-2010
Quote:
Originally Posted by Ultrix
I tested my method and it works perfectly. I also modified it so that it takes an arbitrary range of line lengths, as well as allowing the user to decide whether to write to the file:
Code:
#!/bin/bash
# Deletes lines of a certain range length from a file.
# Writing the result back to the file is optional.

write="no";
for opt in $*
do
    case $opt in
        -w ) write="yes";
             shift;;
        -* ) shift;;
        *  );;
    esac
done
if [ $write == "yes" ]
then
    sed -e "/^.\{$1,$2\}$/d" $3 > tempfile.txt;
    cat tempfile.txt > $3;
    rm tempfile.txt;
else
    sed -e "/^.\{$1,$2\}$/d" $3;
fi

Did you test it with filenames containing IFS characters? Assuming a default IFS value, your option handling, sed invocations, and cat statement will all barf if a filename contains whitespace.

Code:
for opt in $*

should be
Code:
for opt in "$@"

All instances of $3 need to be double-quoted.

Alister
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