Perl provides various operations and functions to process files.

Perl File example

First, To process files for read or write, you have to open the files.

Syntax

open (filehandle,filemode,filepath)

  • filehandler: It is a cursor for a file, also called a file stream or object.

  • file mode: contains three types

    • Reading <
    • Write >
    • Append >>

  • FilePath:

    Path to a file given, ie absolute or relative path

For example, Below line code to open a file for reading,

open ( "handler" , '<', 'test.txt' );

If any error, display an error with an exit from a program execution.

open ( Read , '<' , 'test.txt' ) or die $!;

die $!: die used to exit the program $1 perl variable that displays the error stack message. You can print the file, Finally close the file

close(handler)

How to Create a File in Perl

This is an example of creating a file and writing to a file.

open(my $filehandler, ">", "abc.txt") or die "Unable to open file: $!";

Open is a function that is used for reading and writing a file

The first argument,$filehandler is a variable created with my used to point the newly created file. The second Argument, > indicates modes used for writing. It does the following things

  • Create a file if does not exists
  • if the file already exists, it points to it. and overrides the content.

print function with filehandler variables writes file content to the opened file.

Finally, close the file

# Open the file for writing
open(my $filehandler, ">", "abc.txt") or die "Unable to open file: $!";

# Write to the file
print $filehandler "file content \n";

# Close the file
close $filehandler;

outputs, Create an abc.txt file and contains file content text

How to copy from one file to another file

open (READ, '<', 'test.txt') or die $!;
open (WRITE, '>', 'output.txt') or die $!;
# WHILe loop until End Of File
while(<READ>){
    chomp $_;
    print WRITE "$_\n";
}
close (READ);
close (WRITE);

Perl The Diamond Operator: <>