shell script vs. perl for an install script - how ubiquitous is perl? - perl

I am wanting to create an install script in the fashion of npm's (curl http://example.com/install.sh | sh) but it leaves me asking the question: can I just write the script in perl? As far as I know, perl is installed by default on at least ubuntu, RHEL & OS X - so I'm wondering in the year 2011, can I not write shell and still be generic enough for everyone? Is there a third and better option?
This would be targeting a user's development box, not staging or production.
What I want to do specifically is use this install script to bootstrap a development environment easily without the overhead of creating and maintaining packages. The script would have 4 steps:
check and make sure git is installed
use git to clone a repo to cwd
pull down and save a perl control script to /usr/bin, make it executable
add some environment variables (related post: linux cross-distro environment variable modification via script?)
That's it. My thinking is this is simple and generic enough to use a bootstrap script rather than a package. And my target audience is a user's unix or linux local development system.

The best option is to simply use the existing, well-oiled and -used (development) toolchain for the language the target app is written in. Not doing so frivolously discards the network effects gained from the ecologies that have grown around them.
C: GNU autotools
Haskell: Cabal
Perl: EU::MM, M::B, M::I
etc. etc.
Installing from the Web should be reserved for conveniently bootstrapping a user's system into the development environment.
Do tell more details about your software to get less general advice.
Edit: response to your addendum.
I dissuade you from a Web installer. This isn't bootstrapping an installation tool, this is plain installation of software and it should be done with with e.g. a Module::Build subclass.

I think perl is ubiquitous enough for you to write your installer in it. Shell is a lot more awkward anyway.
You might want to consider actually packaging your application as a deb or rpm or even using makeself rather than providing a raw script.

Here's a list of the various distributions of perl:
https://www.socialtext.net/perl5/distributions
Even if perl doesn't ship on every little obscure distro it's just an apt-get (or whatever) away. You might run into problems due to the various versions of perl installed however.

Use something like:
perl -E "$( wget -q -O - http://host/intall.pl )"
Also you can use
`cmd`
instead of
$(cmd)
but anyway, double-quote your choice.

Related

Installing an perl based web-app in extremely restricted environment

Because i have a long series of comments with #ikegami, I cleaning up the question, in a hope it will be more understandable. Unfortunately, english isn't my "main" language. :(
Let say, having an environment where:
no development tools are installed (no make, nor gcc or like)
perl is installed with its core packages, nothing more
no outgoing network access is allowed - e.g. the user couldn't use curl nor cpan to download/install perl dependencies
the user even doesn't have admin (root) rights
but want install and evaluate some perl based web-app, let call it as MyApp
The MyApp
doesn't uses any XS-based module. (at least, I hope - in the development me using plenv and cpanm, so never checked the installed dependencies in depth)
it is an pure PSGI app, the simple plackup app.psgi works OK
the app uses some data-files which should be included in the "deployment".
The main question is: how to prepare the MyApp, and the all used CPAN-modules, to be easily installed in such restricted environment?
The goal is:
i don't need save my efforts and my time
but i want save the user's time and want minimize the needed actions on his side, so the installation (deployment) should be simple-as-possible.
E.g. how to get an running web-app to the user's machine with minimum possible (his) steps.
- the simplest thing is could be something as:
- copy one file (zip, or tarbal)
- unpack it
- from the terminal execute some run.pl in the unpacked directory.
To get the above simple installation, my idea was the following:
1.) Create an tarball, and after the unpacking will contain 3 folders and 1 perl-script, let say:
myapp_repo/
myapp_repo/distlib #will contain all MyApp's perl modules also ALL used CPAN modules and their dependecies
myapp_repo/datafiles #will contain app-specific data files and such
myapp_repo/install.pl
myall_repo/lib #will contain modules directly used by the `install.pl`
2.) I will develop an install.pl script, and it will be used as the installer-tool, like
perl install.pl new /path/to/app_root
and it will (should):
create the all needed directories under the /path/to/app_root (especially the lib where the will install the perl modules)
will call "local" cpanm internally (from the myapp_repo/lib) to install the app's perl modules and their CPAN dependencies using only distribution files from the distlib.
will generate and install the needed runtime script and the app.psgi into the /path/to/app_root/bin
will install the needed data-files for the app.
3.) So, after this the user should be able to simply run:
/path/to/app_root/bin/plackup /path/to/app_root/bin/app.psgi
In short, the user should use:
the system-wide perl and the system-wide perl-core modules
and any other
runtime perl-scripts (like plackup)
and the required CPAN-modules
should be installed to an self-contained directory tree using only files (no net-access).
E.g. the install.pl should somewhat call internally the cpanm to achieve (as equivalent) for the following cpanm command
cpanm --mirror file://path/to/myapp_repo/distlib --mirror-only My::App
which, should install My::App and all dependencies without network access using only the files from the myapp_repo/distlib
Some questions:
Is possible to use cpanm (called as an locally installed module) without the make?
For creating the myapp_repo/distlib, me thinking about using Pinto. Is it the right tool for achieve the above?
forgot me something? or with other words:
Is the above an viable (read: working) way?
are are any other tools, which i could/should to use for simplifying the creation of such distribution tarball?
#ikegami suggesting some method:
- "install everything" in one fresh-directory on my machine
- transfer this self-contained directory to the target machine
It sound very good, because this directory could contain all the needed app-specific data-files too, unfortunately, I don't understand the details how his solution should be done.
The FatPacked solution looks interesting too - need learn about it.
Don't write your own make or installer. Just copy it make from a different machine (which is basically what apt/yum/etc do anyway, and which you'd have to do even if you wrote your own). You'd be able to use cpan in 5 minutes!
Also, that should allow you to install gcc if you need it (e.g. to install an XS module), although it doesn't sound like you do. If you do install gcc, I'd install my own perl to avoid having to deal with PERL5LIB.
Tools such as minicpan will allow you to install any module from CPAN without internet access. Of course, you can keep using the command you are already using it if mirrors the packages you need.
The above explains how to simply and quickly setup a machine so it can use cpan and thus install any module easily.
If you just want to install a specific module and its dependencies, you can completely avoid using cpan on the target machine. First, you need a fresh install of Perl (preferable of the same version as the one on the target system). Then, simply install the module to a fresh dir on your machine, and transfer that dir to the target machine. That's it; nothing else needs to be done. This even works for XS modules if the two machine are similar enough.
This is what ppm (ActiveState's Perl package manager) does.
Unfortunately, while this solution is almost as simple as the one above, it's not nearly as flexible, it doesn't run the test suite of the modules being installed, etc. It does have the advantage of not requiring the transfer of any binary (if you're not installing any XS modules).

Bundling up a perl script with its dependencies?

I have a perl script that I've put together to do some monitoring and graphing.
It works nicely on my dev system, where I have carte-blanch to install my own modules from CPAN.
What I'm looking at doing is bundling it up to deploy onto another system. But here's the catch - this other system is 'standalone' and has no network connection. (And I have change control paperwork to fill in, indicating what I'm installing).
As a result, I'd really like a nice easy way to figure out:
- What modules my scripts are making use of. (Including dependencies)
- how to easily grab them (cpan get probably)
- Is there an easy way to tell what external binaries I'm using? (I'm using for sure ssh and rrdtool - the former is definitely installed, the latter probably not).
I have a few thoughts on how to do this, but it strikes me as something that should be smoother.
I may also need to deploy a new perl, so I'm pondering whether I'm better off 'installing' the modules with system perl (probably 5.8.8 on RHEL5), or just 'packaging' the whole thing in a directory of it's own with a standalone perl instance.
Use pp to package your script and all dependant modules and libraries into a stand alone executable.
pp -x yourscript.pl -o outputfilename
See the documentation for examples of how to link to external shared objects (etc) if required. With pp you don't need perl on the target system where outputfilename will run.
Revisiting this, as the need hasn't really gone away. I have moved towards using docker - this is an 'image' and 'container' system for app deployment, which amongst other things, allows you to 'package' an application.
You create a Dockerfile - which is analagous to a Makefile - that runs through the steps to install perl + dependencies (either via a package manager, or from CPAN).
Once it has, you have a self contained, runnable 'image' that you can clone and create an instance of (a "container" in docker parlance).
It's also quite useful - even if you don't then deploy via container - to figure out what the dependencies of this application/packages were. The version in the container has everything locally installed that it needed, because it was a clean build.
When you have a system where you can't control the Perl installation (and the install is a really, really old version of Perl like 5.8.8 which is missing many nice improvements like state variables, autodie, say, and switch), you should look into Perlbrew.
Perlbrew allows you to install a user version of Perl. (In fact, it allows you to install multiple versions of Perl), and allows you to switch between the Perlbrew install and the officially installed version. It makes doing everything in Perl much, much easier.
You will have freer access to install new Perl modules, and you can do that task yourself rather than wait for your IT department to do it for you.
I ended up using it on one of our systems where the primitive version of Perl just wasn't doing what my version of Perl did. I originally asked our IT to upgrade, but they really messed up the upgrade. After going back and forth, I simply asked if I could install Perlbrew.
Which is an important point. Always ask permission. A lot of time, the IT department is more than happy to oblige. They're not Perl people, and CPAN is a world they don't want to deal with. Being able to get out of having to answer your beck and call about installing this or that Perl module is a great relief.

how to implement a keyboard listeners or action listeners in Perl

Im working on my final project in Perl. I'm creating an ASCII arcade game that will be ran through terminal. One of the specifications for the project is that our code must be able to run on the school's Linux boxes. Students do not have sudo privileges within the linux evironment so installing modules like Term::ReadKey or Curses would be tricky if not a impossible due to all of there dependency and requirements. So I'm looking for an solution within perl standard libraries or maybe someother work around. Thanks!
If you cannot use sudo, local::lib may be your friend, so you can install modules in your home directory, and no sudo is required.
With local::lib, you can install via cpan the modules you need, like Term::ReadKey.
Or perlbrew (http://perlbrew.pl/) if you have access to build tools.
Another workaround would be to use the core Unix Perl IO support.
e.g. select (perldoc -f select), to do non-blocking keyboard scanning (or set a timeout).
That's how I wrote a tetris clone in Unix/C 25 year ago :)

How to install Perl offline

I have a Linux server that has no access to the internet (access is prevented by a firewall). I would like to install a new Perl. What are my options and what is the best way to do this? The system Perl (included in OS installation) must remain unchanged.
I have been using perlbrew and I think it is the best way to do an online installation. But all the steps involved in perlbrew seem to require internet access: you download it from the net, it downloads new Perl versions from the net etc. and I haven't found a glue how to make it work offline.
If perlbrew is out of question I could build Perl from source into a custom location on the server. I assume that this could end up being complicated, time-consuming and error-prone. And every time I update Perl I have make a new build manually.
There can also be other ways to install that I'm not currently aware of. And of course I could stick with the system Perl but it is an outdated version and I'm already using the new syntax features. Or I could start negotiations to change the firewall policy to allow internet access for perlbrew.
But all the steps involved in perlbrew seem to require internet access
Not if properly configured.
To install perlbrew itself off-line, install the App-perlbrew dist. Following its dependencies manually is a chore, so instead prepare a MiniCPAN mirror (with -p to include Perl dists), take it over to the target machine and configure CPAN to use the local mirror. Run cpan App::perlbrew to install.
After perlbrew is installed, run its mirror command to configure a CPAN mirror into $PERLBREWROOT/Config.pm. Edit this file to change it to the local MiniCPAN mirror. Drop Perl dist tarballs into $PERLBREWROOT/dists/.
Be aware that compiling Perl requires a working C compiler toolchain, and optionally the development files for libdb (BerkeleyDB) and gdbm. (Read the INSTALL file once over, even though perlbrew's autoconfiguration and Perl's configure.SH defaults hide these details from you.)
The compiler toolchain is probably much more difficult to procure off-line, unless the OS installation has already been used before for compiling other C stuff.
There's nothing that special about perlbrew. If you aren't going to use it to download the Perl sources, it's not saving you that much. Once you have the Perl sources, you just need to configure and install it:
% ./Configure -des -Dprefix=/path/to/installation
% make install
Once done, everything for that Perl is under that installation path.
I dislike perlbrew mostly because it hides from people how amazingly simple this task is so they feel like they can't do it on their own.
Have you considered attacking it from a different direction? Keeping this up-to-date is going to be a pain if you have to request internet access each time. Likewise, if you've missed out/misconfigured any packages in your CPAN mirror it's difficult to correct once you're actually trying to use them.
Perhaps just build a small VM with a cut-down linux + perl + modules. Keep that up-to-date at your end and just take the whole lot in on a USB stick. You'd have a known-working easy-to-setup installation.
What I personally do is using git checkout when I'm offline (and not on vacation). Once you have the whole git work directory, it's trivial to build any released version by checking out the tags:
git checkout v5.17.4
git clean -f # cleanup previously compiled .o files etc
sh ./Configure ...
Depending on how you can transfer files to your host, this can be handy, since you you can also setup a private git repo there so other computer can git push new commits to there.

How to run multiple Perl installs on one machine?

Is it possible to run multiple installs of Perl (in "containers") on one machine?
Reason is that I have different Perl-based server side web applications and wish to schedule updates to them independently.
For example, bugzilla upgrades seem to me to be very invasive, downloading all manner or module updates and lengthy, too (thereby increasing the chance of unpredictable behavior on other applications that depend on those modules, during the time that the upgrade is still partial).
I think it should be possible to run multiple independent server-side CGI Perl applications on one server, I'd rather not be told to separate them onto different machines - I think that's wasteful and I don't have that resource anyway.
Investigate PerlBrew and cpanm:
http://qa.celogeek.com/programming/perl/for/developer/overview
Edit, more info:
http://www.bryanesmith.com/documents/a2pm/perlbrew-june-14-2011.pdf
http://www.dagolden.com/index.php/1384/parallel-make-for-perlbrew/
http://www.perlbrew.pl/
It's easy to install and manage multiple perls. Simply install them in different places and use each perl's tools. I talk about this in The Effective Perler.
Some people suggest perlbrew without realizing that it doesn't really give you any benefit. It can download a perl, configure and install it, and switch around symbolic links to make one of those the default. It doesn't do anything magical, though.
Downloading and installing aren't a problem though. You've never needed root or sudo to do that, and if you do, you'll still need it for perlbrew. You can always install into any directory where you have permission. perlbrew doesn't get around that at all. From the source directory, you have two simple commands to run:
$./Configure -des -Dprefix=/where/you/want/to/install
$ make install
For you, that might mean Bugzilla gets its own perl:
$./Configure -des -Dprefix=/where/you/want/to/install/bugzilla-perl
$ make install
From there, you have a completely self-contained perl installation. When it matters to me which perl I use, I give the program the full path to it:
#!/where/you/want/to/install/bugzilla-perl/bin/perl
It's much easier to make these per-applications installations without perlbrew, which wants to do as much as it can for you, including deciding the directory name, which it prefers you didn't know at all.
perlbrew's main advantage is not the compilation and installation, but it's switch feature to let you make one perl the default. You probably don't want that feature though because you want bugzilla, CGI programs, and so on using only the perl you want them to use, not whatever default perl you last specified.
When you want to update the bugzilla-perl, just use it's tools, which already have adjusted shebang lines to find the right perl:
$ /where/you/want/to/install/bugzilla-perl/bin/cpan ...
I don't like all of those long paths, though, which is why I make links to them all. Then I can just call them with whatever naming scheme I decide, which might be:
$ bugzilla-cpan ...
There's never a question about which tool or version I'm using.