perl function syswrite

The syswrite function in Perl is used to write a specified number of bytes to a file or a filehandle. It returns the number of bytes actually written, or undef on error.

Here's an example:

open(my $fh, ">", "file.txt") or die "Couldn't open file.txt: $!";
my $data = "Hello, world!";
my $bytes_written = syswrite($fh, $data, length $data);
close($fh);

print "Wrote $bytes_written bytes to file.txt\n";

In this example, the syswrite function is used to write the string "Hello, world!" to the file "file.txt". The open function is used to create a new filehandle and open the file for writing. The length function is used to get the length of the data string, which is then passed as the third argument to the syswrite function. The number of bytes actually written is assigned to the $bytes_written variable, which is printed on the terminal.

Note that syswrite is a low-level function and is generally used for writing binary data to files or filehandles. For writing text data, it's usually better to use the print function or the printf function. Also, it's important to handle errors when using syswrite, as it can return undef on error.