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