editing text file in perl

[king]

I want to edit a perticular line in a 50 lines text file using perl.

File handle can be used for this.
But how can i edit a string present in say 20th line using perl
script.

 

[Gunnar Hjalmarsson]

I want to edit a perticular line in a 50 lines text file using perl.

That's a FAQ.

perldoc -q "change one line"

 

[Bart Van der Donck]

I want to edit a perticular line in a 50 lines text file using perl.

File handle can be used for this.
But how can i edit a string present in say 20th line using perl
script.

#!perl
use strict;
use warnings;
my $file = 'file.dat';
my $line_counter = 0;
my $new_content;

open my $F, '<', $file || die "Cant open $file: $!";
flock($F, 1) || die "Cant get LOCK_SH on $file: $!";
while(<$F>) {
$line_counter ++;
if ($line_counter == 20) {
# do something on 20th line, eg. change it
$_ = "this is new content of line 20\n";
}
$new_content.= $_;
}
close $F || die "Cant close $file: $!";

# report
print $new_content;

Hope this helps,

 

[Ian Wilson]

king wrote:




#!perl
use strict;
use warnings;
my $file = 'file.dat';
my $line_counter = 0;
my $new_content;

open my $F, '<', $file || die "Cant open $file: $!";
flock($F, 1) || die "Cant get LOCK_SH on $file: $!";
while(<$F>) {
$line_counter ++;
if ($line_counter == 20) {
# do something on 20th line, eg. change it
$_ = "this is new content of line 20\n";
}
$new_content.= $_;
}
close $F || die "Cant close $file: $!";

# report
print $new_content;

I prefer to keep simple jobs simple
perl -pi -e 'if ($.==20) {s/^.*$/new content for line 20/;}' file.dat
or
perl -pi -e '($. == 20) && s/^.*$/new content for line 20/;' file.dat

 

[Gunnar Hjalmarsson]

I prefer to keep simple jobs simple
perl -pi -e 'if ($.==20) {s/^.*$/new content for line 20/;}' file.dat
or
perl -pi -e '($. == 20) && s/^.*$/new content for line 20/;' file.dat

'short' ne 'simple'

 

[Tad McClellan]

'short' ne 'simple'

And attempting to re-answer a Frequently Asked Question is neither.

 

[Nikita Naresh]

Help me

When i try to execute the following command (perl -pi -e 'if ($.==20) {s/^.*$/new content for line 20/;}' file.dat), I get this error message.
"Substitution replacement not terminated at -e line 1."

Kindly guide me with this.