To create a simple Perl script, we can use the text editor of choice. For short scripts vi or vim works well, as does gedit if you want to work in GUI. For larger projects an IDE may help. Often, the IDE will allow you to change the object name easily throughout the script and provide expansion of object names. In this chapter, we will make use of very simple scripts so we will continue to use vi.

We will create a $HOME/bin/hello.pl file to produce the output we want:

#!/usr/bin/perl
print("Hello World
");

The file still needs to be in a directory within our PATH variable; hence, we create $HOME/bin. If it is not in the PATH variable then we will need to specify the full or relative path of the file, as with bash.

The file will need to be set with the execute permission. We can do this with the following command:

$ chmod u+x $HOME/bin/hello.pl

We can run the script with the following command:

$ hello.pl

We can see that the code that we have added is the same as the one we ran the earlier perl -e command with. The only difference is the shebang. This is also quite similar to bash. We now use the print function rather than using the echo command. Bash scripts run a series of commands, whereas Perl scripts run functions. The print function does not automatically add a new line so we add it ourselves using the character. We can also see that the Perl uses the semi-colon to terminate a line of code. The shebang is not a line of code, whereas the print line is terminated with a semicolon.

If we are using Perl version 5.10 or later, on the Pi we have seen that it is 5.14 and we can also make use of a function say. Similar to the print command, this is used to display output but it also includes the newline. We have to enable this feature, which is managed by the use keyword. Either of the following scripts will print Hello World using the say function:

#!/usr/bin/perl
use v5.10;
say("Hello World");

#!/usr/bin/perl
use 5.10.0;
say("Hello World");

The say function also simplifies the printing of files and lists.