I have file with 6000 line from these some are not useful i want to remove those lines by using perl program. Say
input file (input.txt)
............................................................
this is first line
this is second
third
hello
this is second ....
.................................................................
Here the line starting with ... are useless i want to delete them.
Output should be like
output (output.txt)
........................................................................
this is first line
third
hello
.................................................................
Suggest some expressions or program
In PERL you want to do something like this:
my $string = "this is first line
this is second
third
hello
this is second ....";
$string =~ s/.*\/a>\n//g;
You can either feed the entire file in as one string or loop through line by line if you wish using the regular expression and substring replacement.
You can also just use sed from the command line if you don't want to write any code. Like this:
sed 's/.*\/a>\n//g' input.txt > output.txt
This will put your file without the ... lines into output.txt or whatever you call it.
Why perl, when this is trivial in unix?
if file is
this is first line
this is second
third
hello
this is second ....
cat file | grep -v ^""
produces
this is first line
third
hello
I do agree with Eric.
You can use regexp to escape from these extra lines.
For example: if you have multiple files in a folder then,
#!/user/bin/perl
use warnings;
opendir DIR, "replace this with the location of folder containing your input files";
while($f = readdir(DIR))
{
if($f = /.*\.txt/)#replace txt with other file extensions
{
open IN, "location of dir/$f";
open OUT, "location of output dir/$f";
while()
{
chomp;
if($_ = /^(\)/)#if starting with otherwise remove ^
{
next;
}
else
{
print OUT "$_\n";
# you can also add more parsing code here
}
}
close IN;
close OUT;
}
else
{
next;
}
}
closedir DIR;
I hope this helps!
Thank you all for you such explanatory answers. from this i have solved my problem
thanks again.
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