I want to replace a line in my file and after replacing it I want to append another line. As you can see here, I have to open and close files for 2 times. Can I do it by opening a file only once? Thanks
use strict;
use warnings;
open(FILE,"tmp1.txt") || die "Can't open file: $!";
undef $/;
my $file = <FILE>;
my #lines = <FILE>;
my #newlines;
for each(#lines) {
$_ =~ s/hello/hi/g;
push(#newlines,$_);
}
close(FILE);
open(FILE, "> tmp1.txt ") || die "File not found";
print FILE #newlines;
close(FILE);
open(FILE,"tmp1.txt") || die "Can't open file: $!";
undef $/;
my $file = <FILE>;
my #lines = <FILE>;
my $first_line = "hi";
my $second_line = "sun";
my $insert = "good morning";
$file =~ s/\Q$first_line\E\n\Q$second_line\E/$first_line\n$insert\n$second_line/;
open(OUTPUT,"> tmp3.txt") || die "Can't open file: $!";
print OUTPUT $file;
close(OUTPUT);
Use Three-arg open and open your file in Read+Write mode by +<.
Related
I am trying to copy lines of a file to another file.I want to give filenames for both input and output file. I tried to do without asking for any input parameters and it worked fine but with filename as input it failed.Here is my code:
use strict;
use warnings;
#names of file to be input and output
my $inputfile = <STDIN>;
my $outputfile = <STDIN>;
open(INPUT,'<', $inputfile)
or die "Could not open file '$inputfile' $!";
open(OUTPUT, '>', $outputfile)
or die "Could not open file '$outputfile' $!";
while (<INPUT>) {
print OUTPUT;
}
close INPUT;
close OUTPUT;
print "done\n";
chomp your input variables to remove the newlines:
use strict;
use warnings;
#names of file to be input and output
my $inputfile = <STDIN>;
my $outputfile = <STDIN>;
chomp $inputfile;
chomp $outputfile;
open(INPUT,'<', $inputfile)
or die "Could not open file '$inputfile' $!";
open(OUTPUT, '>', $outputfile)
or die "Could not open file '$outputfile' $!";
while (<INPUT>) {
print OUTPUT;
}
close INPUT;
close OUTPUT;
print "done\n";
how can i remove the first line from my list of file , this is my code,
open my directory:
use strict;
use warnings;
use utf8;
use Encode;
use Encode::Guess;
use Devel::Peek;
my $new_directory = '/home/lenovo/corpus';
my $directory = '/home/lenovo/corpus';
open( my $FhResultat, '>:encoding(UTF-8)', $FichierResulat );
my $dir = '/home/corpus';
opendir (DIR, $directory) or die $!;
my #tab;
while (my $file = readdir(DIR)) {
next if ($file eq "." or $file eq ".." );
#print "$file\n";
my $filename_read = decode('utf8', $file);
#print $FichierResulat "$file\n";
push #tab, "$filename_read";
}
closedir(DIR);
open my file:
foreach my $val(#tab){
utf8::encode($val);
my $filename = $val;
open(my $in, '<:utf8', $filename) or die "Unable to open '$filename' for read: $!";
rename file
my $newfile = "$filename.new";
open(my $out, '>:utf8', $newfile) or die "Unable to open '$newfile' for write: $!";
remove the first line
my #ins = <$in>; # read the contents into an array
chomp #ins;
shift #ins; # remove the first element from the array
print $out #ins;
close($in);
close $out;
the probem my new file is empty !
rename $newfile,$filename or die "unable to rename '$newfile' to '$filename': $!";
}
It seems true but the result is an empty file.
The accepted pattern for doing this kind of thing is as follows:
use strict;
use warnings;
my $old_file = '/path/to/old/file.txt';
my $new_file = '/path/to/new/file.txt';
open(my $old, '<', $old_file) or die $!;
open(my $new, '>', $new_file) or die $!;
while (<$old>) {
next if $. == 1;
print $new $_;
}
close($old) or die $!;
close($new) or die $!;
rename($old_file, "$old_file.bak") or die $!;
rename($new_file, $old_file) or die $!;
In your case, we're using $. (the input line number variable) to skip over the first line.
I have this little perl script which opens a txt file, reads the number in it, then overwrites the file with the number incremented by 1. I can open and read from the file, I can write to the file but I"m having issues overwriting. In addition, I'm wondering if there is a way to do this without opening the file twice. Here's my code:
#!/usr/bin/perl
open (FILE, "<", "data.txt") or die "$! error trying to a\
ppend";
undef $/;
$number = <FILE>;
$number = int($number);
$myNumber = $number++;
print $myNumber+'\n';
close(FILE);
open(FILE, ">data.txt") or die "$! error";
print FILE $myNumber;
close(FILE);
Change the line
$myNumber = $number++;
to
$myNumber = $number+1;
That should solve the problem.
Below is how you could do by opening the file just once:
open(FILE, "+<data.txt") or die "$! error";
undef $/;
$number = <FILE>;
$number = int($number);
$myNumber = $number+1;
seek(FILE, 0, 0);
truncate(FILE, tell FILE);
print $myNumber+"\n";
print FILE $myNumber;
close(FILE);
It's good that you used the three-argument form of open the first time. You also needed to do that in your second open. Also, you should use lexical variables, i.e., those which begin with my, in your script--even for your file handles.
You can just increment the variable that holds the number, instead of passing it to a new variable. Also, it's a good idea to use chomp. This things being said, consider the following option:
#!/usr/bin/env perl
use strict;
use warnings;
undef $/;
open my $fhIN, "<", "data.txt" or die "Error trying to open for reading: $!";
chomp( my $number = <$fhIN> );
close $fhIN;
$number++;
open my $fhOUT, ">", "data.txt" or die "Error trying to open for writing: $!";
print $fhOUT $number;
close $fhOUT;
Another option is to use the Module File::Slurp, letting it handle all the I/O operations:
#!/usr/bin/env perl
use strict;
use warnings;
use File::Slurp qw/edit_file/;
edit_file { chomp; $_++ } 'data.txt';
Try this:
#!/usr/bin/perl
use strict;
use warnings;
my $file = "data.txt";
my $number = 0;
my $fh;
if( -e $file ) {
open $fh, "+<", $file or die "Opening '$file' failed, because $!\n";
$number = <$fh>;
seek( $fh, 0, 0 );
} else { # if no data.txt exists - yet
open $fh, ">", $file or die "Creating '$file' failed, because $!\n";
}
$number++;
print "$number\n";
print $fh $number;
close( $fh );
If you're using a bash shell, and you save the code to test.pl, you can test it with:
for i in {1..10}; do ./test.pl; done
Then 'cat data.txt', should show a 10.
I want to extract the desired information from a file and append it into another. the first file consists of some lines as the header without a specific pattern and just ends with the "END OF HEADER" string. I wrote the following code for find the matching line for end of the header:
$find = "END OF HEADER";
open FILEHANDLE, $filename_path;
while (<FILEHANDLE>) {
my $line = $_;
if ($line =~ /$find/) {
#??? what shall I do here???
}
}
, but I don't know how can I get the rest of the file and append it to the other file.
Thank you for any help
I guess if the content of the file isn't enormous you can just load the whole file in a scalar and just split it with the "END OF HEADER" then print the output of the right side of the split in the new file (appending)
open READHANDLE, 'readfile.txt' or die $!;
my $content = do { local $/; <READHANDLE> };
close READHANDLE;
my (undef,$restcontent) = split(/END OF HEADER/,$content);
open WRITEHANDLE, '>>writefile.txt' or die $!;
print WRITEHANDLE $restcontent;
close WRITEHANDLE;
This code will take the filenames from the command line, print all files up to END OF HEADER from the first file, followed by all lines from the second file. Note that the output is sent to STDOUT so you will have to redirect the output, like this:
perl program.pl headfile.txt mainfile.txt > newfile.txt
Update Now modified to print all of the first file after the line END OF HEADER followed by all of the second file
use strict;
use warnings;
my ($header_file, $main_file) = #ARGV;
open my $fh, '<', $header_file or die $!;
my $print;
while (<$fh>) {
print if $print;
$print ||= /END OF HEADER/;
}
open $fh, '<', $main_file or die $!;
print while <$fh>;
use strict;
use warnings;
use File::Slurp;
my #lines = read_file('readfile.txt');
while ( my $line = shift #lines) {
next unless ($line =~ m/END OF HEADER/);
last;
}
append_file('writefile.txt', #lines);
I believe this will do what you need:
use strict;
use warnings;
my $find = 'END OF HEADER';
my $fileContents;
{
local $/;
open my $fh_read, '<', 'theFile.txt' or die $!;
$fileContents = <$fh_read>;
}
my ($restOfFile) = $fileContents =~ /$find(.+)/s;
open my $fh_write, '>>', 'theFileToAppend.txt' or die $!;
print $fh_write $restOfFile;
close $fh_write;
my $status = 0;
my $find = "END OF HEADER";
open my $fh_write, '>', $file_write
or die "Can't open file $file_write $!";
open my $fh_read, '<', $file_read
or die "Can't open file $file_read $!";
LINE:
while (my $line = <$fh_read>) {
if ($line =~ /$find/) {
$status = 1;
next LINE;
}
print $fh_write $line if $status;
}
close $fh_read;
close $fh_write;
I am stuck trying to get this to write out the contents of the file. What I am trying to do is open an input file, filter out/remove the matched line and write to a new file. Can someone show me how to do this properly? Thanks.
use strict;
use warnings;
use Text::CSV_XS;
my $csv = Text::CSV_XS->new ({ binary => 1 }) or
die "Cannot use CSV: ".Text::CSV_XS->error_diag ();
open my $fh, "<:encoding(UTF-16LE)", "InputFile.txt" or die "cannot open file: $!";
my #rows;
while (my $row = $csv->getline ($fh)) {
my #lines;
shift #lines if $row->[0] =~ m/Global/;
my $newfile = "NewFile.txt";
open(my $newfh, '>', $newfile) or die "Can't open";
print $newfh #lines;
}
$csv->eof or $csv->error_diag ();
close $fh;
Open the output file outside of the loop. As you read each line, decide if you want to keep it. If yes, write to output file. If not, don't do anything.
Something like the following (untested):
use strict;
use warnings;
use Text::CSV_XS;
my ($input_file, $output_file) = qw(InputFile.txt NewFile.txt);
my $csv = Text::CSV_XS->new ({ binary => 1 })
or die sprintf("Cannot use CSV: %s\n", Text::CSV_XS->error_diag);
open my $infh, "<:encoding(UTF-16LE)", $input_file
or die "Cannot open '$input_file': $!";
open my $outfh, '>', $output_file
or die "Cannot open '$output_file': $!";
while (my $row = $csv->getline($infh)) {
next if $row->[0] =~ m/Global/;
unless ( $csv->print($outfh, $row) ) {
die sprintf("Error writing to '%s': %s",
$output_file,
$csv->error_diag
);
}
}
close $outfh
or die "Cannot close '$output_file': $!";
close $infh
or die "Cannot close '$input_file': $!";
$csv->eof
or die "Processing of '$input_file' terminated prematurely";