NAME

NAME
local::lib - create and use a local lib/ for perl modules with PERL5LIB

SYNOPSIS
In code -

use local::lib; # sets up a local lib at ~/perl5

use local::lib '~/foo'; # same, but ~/foo

# Or...
use FindBin;
use local::lib "$FindBin::Bin/../support"; # app-local support library

From the shell -

# Install LWP and its missing dependencies to the '~/perl5' directory
perl -MCPAN -Mlocal::lib -e 'CPAN::install(LWP)'

# Just print out useful shell commands
$ perl -Mlocal::lib
PERL_MB_OPT='--install_base /home/username/perl5'; export PERL_MB_OPT;
PERL_MM_OPT='INSTALL_BASE=/home/username/perl5'; export PERL_MM_OPT;
PERL5LIB="/home/username/perl5/lib/perl5"; export PERL5LIB;
PATH="/home/username/perl5/bin:$PATH"; export PATH;
PERL_LOCAL_LIB_ROOT="/home/usename/perl5:$PERL_LOCAL_LIB_ROOT"; export PERL_LOCAL_LIB_ROOT;

From a .bash_profile or .bashrc file -

eval "$(perl -I$HOME/perl5/lib/perl5 -Mlocal::lib)"

The bootstrapping technique
A typical way to install local::lib is using what is known as the
"bootstrapping" technique. You would do this if your system
administrator hasn't already installed local::lib. In this case, you'll
need to install local::lib in your home directory.

Even if you do have administrative privileges, you will still want to
set up your environment variables, as discussed in step 4. Without this,
you would still install the modules into the system CPAN installation
and also your Perl scripts will not use the lib/ path you bootstrapped
with local::lib.

By default local::lib installs itself and the CPAN modules into ~/perl5.

Windows users must also see "Differences when using this module under
Win32".

1. Download and unpack the local::lib tarball from CPAN (search for
"Download" on the CPAN page about local::lib). Do this as an
ordinary user, not as root or administrator. Unpack the file in your
home directory or in any other convenient location.

2. Run this:

perl Makefile.PL --bootstrap

If the system asks you whether it should automatically configure as
much as possible, you would typically answer yes.

In order to install local::lib into a directory other than the
default, you need to specify the name of the directory when you call
bootstrap, as follows:

perl Makefile.PL --bootstrap=~/foo

3. Run this: (local::lib assumes you have make installed on your
system)

make test && make install

4. Now we need to setup the appropriate environment variables, so that
Perl starts using our newly generated lib/ directory. If you are
using bash or any other Bourne shells, you can add this to your
shell startup script this way:

echo 'eval "$(perl -I$HOME/perl5/lib/perl5 -Mlocal::lib)"' >>~/.bashrc

If you are using C shell, you can do this as follows:

/bin/csh
echo $SHELL
/bin/csh
echo 'eval `perl -I$HOME/perl5/lib/perl5 -Mlocal::lib`' >> ~/.cshrc

If you passed to bootstrap a directory other than default, you also
need to give that as import parameter to the call of the local::lib
module like this way:

echo 'eval "$(perl -I$HOME/foo/lib/perl5 -Mlocal::lib=$HOME/foo)"' >>~/.bashrc

After writing your shell configuration file, be sure to re-read it
to get the changed settings into your current shell's environment.
Bourne shells use ". ~/.bashrc" for this, whereas C shells use
"source ~/.cshrc".

If you're on a slower machine, or are operating under draconian disk
space limitations, you can disable the automatic generation of manpages
from POD when installing modules by using the "--no-manpages" argument
when bootstrapping:

perl Makefile.PL --bootstrap --no-manpages

To avoid doing several bootstrap for several Perl module environments on
the same account, for example if you use it for several different
deployed applications independently, you can use one bootstrapped
local::lib installation to install modules in different directories
directly this way:

cd ~/mydir1
perl -Mlocal::lib=./
eval $(perl -Mlocal::lib=./) ### To set the environment for this shell alone
printenv ### You will see that ~/mydir1 is in the PERL5LIB
perl -MCPAN -e install ... ### whatever modules you want
cd ../mydir2
... REPEAT ...

If you use .bashrc to activate a local::lib automatically, the
local::lib will be re-enabled in any sub-shells used, overriding
adjustments you may have made in the parent shell. To avoid this, you
can initialize the local::lib in .bash_profile rather than .bashrc, or
protect the local::lib invocation with a $SHLVL check:

[ $SHLVL -eq 1 ] && eval "$(perl -I$HOME/perl5/lib/perl5 -Mlocal::lib)"

If you are working with several "local::lib" environments, you may want
to remove some of them from the current environment without disturbing
the others. You can deactivate one environment like this (using bourne
sh):

eval $(perl -Mlocal::lib=--deactivate,~/path)

which will generate and run the commands needed to remove "~/path" from
your various search paths. Whichever environment was activated most
recently will remain the target for module installations. That is, if
you activate "~/path_A" and then you activate "~/path_B", new modules
you install will go in "~/path_B". If you deactivate "~/path_B" then
modules will be installed into "~/pathA" -- but if you deactivate
"~/path_A" then they will still be installed in "~/pathB" because pathB
was activated later.

You can also ask "local::lib" to clean itself completely out of the
current shell's environment with the "--deactivate-all" option. For
multiple environments for multiple apps you may need to include a
modified version of the "use FindBin" instructions in the "In code"
sample above. If you did something like the above, you have a set of
Perl modules at "~/mydir1/lib". If you have a script at
"~/mydir1/scripts/myscript.pl", you need to tell it where to find the
modules you installed for it at "~/mydir1/lib".

In "~/mydir1/scripts/myscript.pl":

use strict;
use warnings;
use local::lib "$FindBin::Bin/.."; ### points to ~/mydir1 and local::lib finds lib
use lib "$FindBin::Bin/../lib"; ### points to ~/mydir1/lib

Put this before any BEGIN { ... } blocks that require the modules you
installed.

Differences when using this module under Win32
To set up the proper environment variables for your current session of
"CMD.exe", you can use this:

C:\>perl -Mlocal::lib
set PERL_MB_OPT=--install_base C:\DOCUME~1\ADMINI~1\perl5
set PERL_MM_OPT=INSTALL_BASE=C:\DOCUME~1\ADMINI~1\perl5
set PERL5LIB=C:\DOCUME~1\ADMINI~1\perl5\lib\perl5
set PATH=C:\DOCUME~1\ADMINI~1\perl5\bin;%PATH%

### To set the environment for this shell alone
C:\>perl -Mlocal::lib > %TEMP%\tmp.bat && %TEMP%\tmp.bat && del %TEMP%\tmp.bat
### instead of $(perl -Mlocal::lib=./)

If you want the environment entries to persist, you'll need to add them
to the Control Panel's System applet yourself or use
App::local::lib::Win32Helper.

The "~" is translated to the user's profile directory (the directory
named for the user under "Documents and Settings" (Windows XP or
earlier) or "Users" (Windows Vista or later)) unless $ENV{HOME} exists.
After that, the home directory is translated to a short name (which
means the directory must exist) and the subdirectories are created.

PowerShell
local::lib also supports PowerShell, and can be used with the
"Invoke-Expression" cmdlet.

Invoke-Expression "$(perl -Mlocal::lib)"

RATIONALE
The version of a Perl package on your machine is not always the version
you need. Obviously, the best thing to do would be to update to the
version you need. However, you might be in a situation where you're
prevented from doing this. Perhaps you don't have system administrator
privileges; or perhaps you are using a package management system such as
Debian, and nobody has yet gotten around to packaging up the version you
need.

local::lib solves this problem by allowing you to create your own
directory of Perl packages downloaded from CPAN (in a multi-user system,
this would typically be within your own home directory). The existing
system Perl installation is not affected; you simply invoke Perl with
special options so that Perl uses the packages in your own local package
directory rather than the system packages. local::lib arranges things so
that your locally installed version of the Perl packages takes
precedence over the system installation.

If you are using a package management system (such as Debian), you don't
need to worry about Debian and CPAN stepping on each other's toes. Your
local version of the packages will be written to an entirely separate
directory from those installed by Debian.

DESCRIPTION
This module provides a quick, convenient way of bootstrapping a
user-local Perl module library located within the user's home directory.
It also constructs and prints out for the user the list of environment
variables using the syntax appropriate for the user's current shell (as
specified by the "SHELL" environment variable), suitable for directly
adding to one's shell configuration file.

More generally, local::lib allows for the bootstrapping and usage of a
directory containing Perl modules outside of Perl's @INC. This makes it
easier to ship an application with an app-specific copy of a Perl
module, or collection of modules. Useful in cases like when an upstream
maintainer hasn't applied a patch to a module of theirs that you need
for your application.

On import, local::lib sets the following environment variables to
appropriate values:

PERL_MB_OPT
PERL_MM_OPT
PERL5LIB
PATH
PERL_LOCAL_LIB_ROOT

When possible, these will be appended to instead of overwritten
entirely.

These values are then available for reference by any code after import.

CREATING A SELF-CONTAINED SET OF MODULES
See lib::core::only for one way to do this - but note that there are a
number of caveats, and the best approach is always to perform a build
against a clean perl (i.e. site and vendor as close to empty as
possible).

IMPORT OPTIONS
Options are values that can be passed to the "local::lib" import besides
the directory to use. They are specified as "use local::lib '--option'[,
path];" or "perl -Mlocal::lib=--option[,path]".

--deactivate
Remove the chosen path (or the default path) from the module search
paths if it was added by "local::lib", instead of adding it.

--deactivate-all
Remove all directories that were added to search paths by "local::lib"
from the search paths.

--shelltype
Specify the shell type to use for output. By default, the shell will be
detected based on the environment. Should be one of: "bourne", "csh",
"cmd", or "powershell".

--no-create
Prevents "local::lib" from creating directories when activating dirs.
This is likely to cause issues on Win32 systems.

CLASS METHODS
ensure_dir_structure_for
Arguments: $path
Return value: None

Attempts to create a local::lib directory, including subdirectories and
all required parent directories. Throws an exception on failure.

print_environment_vars_for
Arguments: $path
Return value: None

Prints to standard output the variables listed above, properly set to
use the given path as the base directory.

build_environment_vars_for
Arguments: $path
Return value: %environment_vars

Returns a hash with the variables listed above, properly set to use the
given path as the base directory.

setup_env_hash_for
Arguments: $path
Return value: None

Constructs the %ENV keys for the given path, by calling
"build_environment_vars_for".

active_paths
Arguments: None
Return value: @paths

Returns a list of active "local::lib" paths, according to the
"PERL_LOCAL_LIB_ROOT" environment variable and verified against what is
really in @INC.

install_base_perl_path
Arguments: $path
Return value: $install_base_perl_path

Returns a path describing where to install the Perl modules for this
local library installation. Appends the directories "lib" and "perl5" to
the given path.

lib_paths_for
Arguments: $path
Return value: @lib_paths

Returns the list of paths perl will search for libraries, given a base
path. This includes the base path itself, the architecture specific
subdirectory, and perl version specific subdirectories. These paths may
not all exist.

install_base_bin_path
Arguments: $path
Return value: $install_base_bin_path

Returns a path describing where to install the executable programs for
this local library installation. Appends the directory "bin" to the
given path.

installer_options_for
Arguments: $path
Return value: %installer_env_vars

Returns a hash of environment variables that should be set to cause
installation into the given path.

resolve_empty_path
Arguments: $path
Return value: $base_path

Builds and returns the base path into which to set up the local module
installation. Defaults to "~/perl5".

resolve_home_path
Arguments: $path
Return value: $home_path

Attempts to find the user's home directory. If installed, uses
"File::HomeDir" for this purpose. If no definite answer is available,
throws an exception.

resolve_relative_path
Arguments: $path
Return value: $absolute_path

Translates the given path into an absolute path.

resolve_path
Arguments: $path
Return value: $absolute_path

Calls the following in a pipeline, passing the result from the previous
to the next, in an attempt to find where to configure the environment
for a local library installation: "resolve_empty_path",
"resolve_home_path", "resolve_relative_path". Passes the given path
argument to "resolve_empty_path" which then returns a result that is
passed to "resolve_home_path", which then has its result passed to
"resolve_relative_path". The result of this final call is returned from
"resolve_path".

OBJECT INTERFACE
new
Arguments: %attributes
Return value: $local_lib

Constructs a new "local::lib" object, representing the current state of
@INC and the relevant environment variables.

ATTRIBUTES
roots
An arrayref representing active "local::lib" directories.

inc
An arrayref representing @INC.

libs
An arrayref representing the PERL5LIB environment variable.

bins
An arrayref representing the PATH environment variable.

extra
A hashref of extra environment variables (e.g. "PERL_MM_OPT" and
"PERL_MB_OPT")

no_create
If set, "local::lib" will not try to create directories when activating
them.

OBJECT METHODS
clone
Arguments: %attributes
Return value: $local_lib

Constructs a new "local::lib" object based on the existing one,
overriding the specified attributes.

activate
Arguments: $path
Return value: $new_local_lib

Constructs a new instance with the specified path active.

deactivate
Arguments: $path
Return value: $new_local_lib

Constructs a new instance with the specified path deactivated.

deactivate_all
Arguments: None
Return value: $new_local_lib

Constructs a new instance with all "local::lib" directories deactivated.

environment_vars_string
Arguments: [ $shelltype ]
Return value: $shell_env_string

Returns a string to set up the "local::lib", meant to be run by a shell.

build_environment_vars
Arguments: None
Return value: %environment_vars

Returns a hash with the variables listed above, properly set to use the
given path as the base directory.

setup_env_hash
Arguments: None
Return value: None

Constructs the %ENV keys for the given path, by calling
"build_environment_vars".

setup_local_lib
Constructs the %ENV hash using "setup_env_hash", and set up @INC.

A WARNING ABOUT UNINST=1
Be careful about using local::lib in combination with "make install
UNINST=1". The idea of this feature is that will uninstall an old
version of a module before installing a new one. However it lacks a
safety check that the old version and the new version will go in the
same directory. Used in combination with local::lib, you can potentially
delete a globally accessible version of a module while installing the
new version in a local place. Only combine "make install UNINST=1" and
local::lib if you understand these possible consequences.

LIMITATIONS
* Directory names with spaces in them are not well supported by the
perl toolchain and the programs it uses. Pure-perl distributions
should support spaces, but problems are more likely with dists that
require compilation. A workaround you can do is moving your
local::lib to a directory with spaces after you installed all
modules inside your local::lib bootstrap. But be aware that you
can't update or install CPAN modules after the move.

* Rather basic shell detection. Right now anything with csh in its
name is assumed to be a C shell or something compatible, and
everything else is assumed to be Bourne, except on Win32 systems. If
the "SHELL" environment variable is not set, a Bourne-compatible
shell is assumed.

* Kills any existing PERL_MM_OPT or PERL_MB_OPT.

* Should probably auto-fixup CPAN config if not already done.

* On VMS and MacOS Classic (pre-OS X), local::lib loads File::Spec.
This means any File::Spec version installed in the local::lib will
be ignored by scripts using local::lib. A workaround for this is
using "use lib "$local_lib/lib/perl5";" instead of using
"local::lib" directly.

* Conflicts with ExtUtils::MakeMaker's "PREFIX" option. "local::lib"
uses the "INSTALL_BASE" option, as it has more predictable and sane
behavior. If something attempts to use the "PREFIX" option when
running a Makefile.PL, ExtUtils::MakeMaker will refuse to run, as
the two options conflict. This can be worked around by temporarily
unsetting the "PERL_MM_OPT" environment variable.

* Conflicts with Module::Build's "--prefix" option. Similar to the
previous limitation, but any "--prefix" option specified will be
ignored. This can be worked around by temporarily unsetting the
"PERL_MB_OPT" environment variable.

Patches very much welcome for any of the above.

* On Win32 systems, does not have a way to write the created
environment variables to the registry, so that they can persist
through a reboot.

TROUBLESHOOTING
If you've configured local::lib to install CPAN modules somewhere in to
your home directory, and at some point later you try to install a module
with "cpan -i Foo::Bar", but it fails with an error like: "Warning: You
do not have permissions to install into
/usr/lib64/perl5/site_perl/5.8.8/x86_64-linux at
/usr/lib64/perl5/5.8.8/Foo/Bar.pm" and buried within the install log is
an error saying "'INSTALL_BASE' is not a known MakeMaker parameter
name", then you've somehow lost your updated ExtUtils::MakeMaker module.

To remedy this situation, rerun the bootstrapping procedure documented
above.

Then, run "rm -r ~/.cpan/build/Foo-Bar*"

Finally, re-run "cpan -i Foo::Bar" and it should install without
problems.

ENVIRONMENT
SHELL
COMSPEC
local::lib looks at the user's "SHELL" environment variable when
printing out commands to add to the shell configuration file.

On Win32 systems, "COMSPEC" is also examined.

SEE ALSO
* Perl Advent article, 2011
<http://perladvent.org/2011/2011-12-01.html>

SUPPORT
IRC:

Join #local-lib on irc.perl.org.

AUTHOR
Matt S Trout <[email protected]> http://www.shadowcat.co.uk/

auto_install fixes kindly sponsored by http://www.takkle.com/

CONTRIBUTORS
Patches to correctly output commands for csh style shells, as well as
some documentation additions, contributed by Christopher Nehren
<[email protected]>.

Doc patches for a custom local::lib directory, more cleanups in the
english documentation and a german documentation contributed by Torsten
Raudssus <[email protected]>.

Hans Dieter Pearcey <[email protected]> sent in some additional tests for
ensuring things will install properly, submitted a fix for the bug
causing problems with writing Makefiles during bootstrapping,
contributed an example program, and submitted yet another fix to ensure
that local::lib can install and bootstrap properly. Many, many thanks!

pattern of Freenode IRC contributed the beginnings of the
Troubleshooting section. Many thanks!

Patch to add Win32 support contributed by Curtis Jewell
<[email protected]>.

Warnings for missing PATH/PERL5LIB (as when not running interactively)
silenced by a patch from Marco Emilio Poleggi.

Mark Stosberg <[email protected]> provided the code for the now
deleted '--self-contained' option.

Documentation patches to make win32 usage clearer by David Mertens
<[email protected]> (run4flat).

Brazilian portuguese translation and minor doc patches contributed by
Breno G. de Oliveira <[email protected]>.

Improvements to stacking multiple local::lib dirs and removing them from
the environment later on contributed by Andrew Rodland
<[email protected]>.

Patch for Carp version mismatch contributed by Hakim Cassimally
<[email protected]>.

Rewrite of internals and numerous bug fixes and added features
contributed by Graham Knop <[email protected]>.

COPYRIGHT
Copyright (c) 2007 - 2013 the local::lib "AUTHOR" and "CONTRIBUTORS" as
listed above.

LICENSE
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.