** Summary **

`[[file join]` joins together elements to form a file path


** See Also **

   [file]:   

   [file separator]:   

   [file split]:   

   [Tilde Substitution]:   


** Synopsis **


    :   '''file join''' ''name ?name ...?''


** Documentation **

   [http://www.tcl.tk/man/tcl/TclCmd/file.htm%|%man page]:   


** Description **

'''`[[file join]`''' joins zero or more strings using the correct
platform-dependent separators so that the result can be interpreted as a path
name.  If a particular ''name'' is relative, then it will be joined to the
previous file name argument.  Any argument that is an absolute path causes all
previous arguments to be discarded, and any additional arguments will then be
joined to it.  For example,

======
file join a b /foo bar
======

returns

======none
/foo/bar
======

Note that any of the names can contain separators, and that the result is
always canonical for the current platform: '''/''' for Unix and Windows, and
''':''' for pre-OSX Macintosh. 


`[[file join]` does not join items in lists.  If a list contains path elements
to be joined, use [Argument expansion]:

======
file join {*}[file split a/b/c]
======

If the `[{*}]` operator is not available in your version of Tcl, and it isn't
feasible to upgrade, see `[[[eval]` for the proper way to use `[[[eval]]` to
expand a list.

Another example:

======
set path a/b/c/d/e/f/g; set common_length 3
set path [file join {*}[lrange [file split $path] $common_length end]]
======

Or, ror historic versions of Tcl without the `[{*}]` operator:

======
set path a/b/c/d/e/f/g; set common_length 3
set script {file join}
set script [concat $script [lrange [file split $path] $common_length end]]
set path [eval $script]
puts $path
======

One reaon `[[[file join]]` doesn't join list elements is that its behaviour
would then be incorrect in the following case:

======
#warning: bad code ahead!
file join "C:/Program Files/Tcl"
======



** The `[[[pwd]]` Trick **

One way to convert a file type from (possibly) relative to absolute is this:

======
set filename [file join [pwd] $filename]
======

[DKF]: Note that you never need to use `[[[cd]]`, and it is best if you don't
except in response to user action. Otherwise you just confuse your users...
:^/


** Using `[[file join]` to Normalize Path Separators **

`[[file join]` can be used to "normalize" the path separators for relative
paths that you don't want to subject to the full `[[[file normalize]]`:

======none
% file join {\foo\bar\grill}
/foo/bar/grill
======

Back the other way with ''file nativename'':

======
% file nativename /foo/bar/grill
\foo\bar\grill
======


** Escaping Tilde Substitution **

To join a file whose name begins with "~" (tilde), prefix it with "./":

======
file join pwd ./~filename.ext
======

See [Tilde Substitution]



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