/usr/share/tcltk/critcl-platform/pkgIndex.tcl is in critcl 3.1.9-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 | package ifneeded critcl::platform 1.0.11 [list source [file join $dir platform.tcl]]
package ifneeded critcl::platform::shell 1.1.4 [list source [file join $dir shell.tcl]]
|