IOS now comes with TCL libraries built into them for TCL hacking. E.g.
test0#sho ver | inc REL
Cisco IOS Software, 7200 Software (C7200-JK9S-M), Version 12.4(18), RELEASE SOFTWARE (fc1)
test0#dir system:/lib/tcl
Directory of system:/lib/tcl/
135 -r-- 19247 <no date> auto.tcl
145 -r-- 2577 <no date> base.tcl
147 -r-- 7680 <no date> cli_lib.tcl
148 -r-- 2589 <no date> context_lib.tcl
131 dr-x 0 <no date> eem_lib_user
129 dr-x 0 <no date> eem_scripts
130 dr-x 0 <no date> eem_scripts_registered
150 -r-- 185 <no date> email_template_cfg.tm
151 -r-- 147 <no date> email_template_chs.tm
152 -r-- 154 <no date> email_template_cmd.tm
153 -r-- 156 <no date> email_template_dmp.tm
154 -r-- 144 <no date> email_template_sl.tm
155 -r-- 350 <no date> email_template_sm.tm
156 -r-- 135 <no date> email_template_wd.tm
136 -r-- 9156 <no date> history.tcl
137 -r-- 23517 <no date> http.tcl
141 -r-- 17744 <no date> init.tcl
143 -r-- 6953 <no date> ldAout.tcl
146 -r-- 33266 <no date> optparse.tcl
138 -r-- 19436 <no date> package.tcl
142 -r-- 1035 <no date> parray.tcl
139 -r-- 32745 <no date> safe.tcl
149 -r-- 10371 <no date> smtp_lib.tcl
144 -r-- 13659 <no date> tclIndex
140 -r-- 4520 <no date> word.tcl
No space information available