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 .bashrc file -

      [ $SHLVL -eq 1 ] && eval "$(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 '[ $SHLVL -eq 1 ] && eval "$(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 '[ $SHLVL -eq 1 ] && eval "$(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 ...

    When used in a ".bashrc" file, it is recommended that you protect
    against re-activating a directory in a sub-shell. This can be done by
    checking the $SHLVL variable as shown in synopsis. Without this,
    sub-shells created by the user or other programs will override changes
    made to the parent shell's environment.

    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 the given path, 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 <mst@shadowcat.co.uk> 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
    <apeiron@cpan.org>.

    Doc patches for a custom local::lib directory, more cleanups in the
    english documentation and a german documentation contributed by Torsten
    Raudssus <torsten@raudssus.de>.

    Hans Dieter Pearcey <hdp@cpan.org> 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
    <csjewell@cpan.org>.

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

    Mark Stosberg <mark@summersault.com> provided the code for the now
    deleted '--self-contained' option.

    Documentation patches to make win32 usage clearer by David Mertens
    <dcmertens.perl@gmail.com> (run4flat).

    Brazilian portuguese translation and minor doc patches contributed by
    Breno G. de Oliveira <garu@cpan.org>.

    Improvements to stacking multiple local::lib dirs and removing them from
    the environment later on contributed by Andrew Rodland
    <arodland@cpan.org>.

    Patch for Carp version mismatch contributed by Hakim Cassimally
    <osfameron@cpan.org>.

    Rewrite of internals and numerous bug fixes and added features
    contributed by Graham Knop <haarg@haarg.org>.

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.