Add section on running ad-hoc Perl programs to the nixpkgs manual

Co-authored-by: Timo Kaufmann <timokau@zoho.com>
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Arnout Engelen 2020-05-02 15:50:30 +02:00
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@ -3,6 +3,39 @@
xml:id="sec-language-perl">
<title>Perl</title>
<section xml:id="ssec-perl-running">
<title>Running perl programs on the shell</title>
<para>
When executing a Perl script, it is possible you get an error such as <literal>./myscript.pl: bad interpreter: /usr/bin/perl: no such file or directory</literal>. This happens when the script expects Perl to be installed at <filename>/usr/bin/perl</filename>, which is not the case when using Perl from nixpkgs. You can fix the script by changing the first line to:
<programlisting>
#!/usr/bin/env perl
</programlisting>
to take the Perl installation from the <literal>PATH<literal> environment variable, or invoke Perl directly with:
<screen>
<prompt>$ </prompt>perl ./myscript.pl
</screen>
</para>
<para>
When the script is using a Perl library that is not installed globally, you might get an error such as <literal>Can't locate DB_File.pm in @INC (you may need to install the DB_File module)</literal>. In that case, you can use <command>nix-shell</command> to start an ad-hoc shell with that library installed, for instance:
<screen>
<prompt>$ </prompt>nix-shell -p perl perlPackages.DBFile --run ./myscript.pl
</screen>
</para>
<para>
If you are always using the script in places where <command>nix-shell</command> is available, you can embed the <command>nix-shell</command> invocation in the shebang like this:
<programlisting>
#!/usr/bin/env nix-shell
#! nix-shell -i perl -p perl perlPackages.DBFile
</programlisting>
</para>
</section>
<section xml:id="ssec-perl-packaging">
<title>Packaging Perl programs</title>
<para>
Nixpkgs provides a function <varname>buildPerlPackage</varname>, a generic package builder function for any Perl package that has a standard <varname>Makefile.PL</varname>. Its implemented in <link
xlink:href="https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/perl-modules/generic"><filename>pkgs/development/perl-modules/generic</filename></link>.
@ -159,3 +192,4 @@ ImageExifTool = buildPerlPackage {
</para>
</section>
</section>
</section>