'''`$[env](TCLLIBPATH)`''' is a `[list]` of directories to add to `[Tcl Library%|%$auto_path]`, which in turn is used by facilities such as `[package unknown]` to search for [package%|%packages]. 


** See Also **

   [auto_path]:   

   [magic names]:   

   `[TCL_LIBRARY%|%$env(TCL_LIBRARY)]`:   



** Description **

`$[env](TCLLIBPATH)` is a Tcl [list], not some platform-specific
colon-separated or semi-colon separated format, of paths to prepend to
`$[auto_path]`.  Regardless of platform, each item in `$[env](TCLLIBPATH)`
should use `/` to delimit parts of a path.

Example:

======
set env(TCLLIBPATH) [list /opt/tcl/site-lib /users/pat/working]
======

`$[env](TCLLIBPATH)` is often not set by Tcl, and is designed to be set on a case-by-case basis depending on the needs of the site or the  individual user to provide Tcl with additional site-specific
locations to search for packages, or to test a package without installing it.



<<discussion>>Further Discussion and Examples

[PT] 2004-07-20:   

I like to keep all my local packages separate from the [ActiveTcl] installation that I use as a 
base. So I install all additional packages to a ''site-lib'' directory and then set `$[env](TCLLIBPATH)`
to this directory path. With this in place `[package require] XYZ` searches [ActiveTcl] 
'''and''' my ''site-lib'' directory for the most recent version of XYZ.



** Determining which directory to add to TCLLIBPATH **

[LV] 2009-06-29:

I download a package onto my machine. The package has a README, a demo directory, a lib directory, etc. Within the lib directory I see 3 sub-directories, and within the sub-directories are the [pkgIndex.tcl] file, etc. 

So the basic layout is:

======
Installation directory/
 README.txt
 demos/
 lib/
  package1/
    pkgIndex.tcl 
  package2/
    pkgIndex.tcl
  package3/
    pkgIndex.tcl
 src/
 tests/
======

So, what path(s) go into TCLLIBPATH? the path to the lib/, or each of the individual packages?

Thanks!

[PT]: the lib directory.

[LV] PT, thank you for the answer. I tried using that, and ran into my long time nemesis - Windows folders with spaces in the names. 
So eventually, when I have time, I need to change to using `[file join]` to set `$[env](TCLLIBPATH)` rather than just hard coding it, so that it has some chance of working.  


** Example: [Microsoft Windows%|%Windows] with [Git] version 1.7.10-preview20120409 **

[LGT]: 

I ran git, then do 'cd' to be in HOME directory and then add file .bashrc with these lines:

======none
$ cd
$ cat .bashrc
TCLLIBPATH=" . C:/Tcl/lib"
export TCLLIBPATH
$ 
======

Then at the next start of git, you will be able to use library packages from external (to git) Tcl installation (for instance [Activestate] Tcl).

Space character seems to be required at the beginning of `$[env](TCLLIBPATH)`: you can try the following lines on command line to experience it

======none
$ unset TCLLIBPATH
$ TCLLIBPATH=". C:/Tcl/lib"
$ export TCLLIBPATH
$ tclsh
% package require Expect
can't find package Expect
% exit
$ TCLLIBPATH=" . C:/Tcl/lib "
$ export TCLLIBPATH
$ tclsh
% package require Expect
5.43.2
% exit
$
======

[PYK] 2014-05-23: This statement about the space character doesn't sound
plausible. Could someone confirm or deny ? [APN] Works for me without the space. At least for 8.6.0.

[DKF]: It's a ''Tcl [list]''. That should tell you exactly how to make things work, and should also indicate that leading and trailing whitespace will be ignored.

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