| Tcl | Shell | What it Does |
|---|---|---|
| { } | ' ' | prevents variable, command, or backslash substitution |
| [ ] | ` ` | performs command substitution |
Strings are the only data type in Tcl, although numeric calculation is possible with the expr function. The Tcl language contains a collection of list manipulation facilities including append, insert, search, replace, join, split, and sort procedures.
New procedures can be written in Tcl using the proc keyword, or bound to compiled C or C++ procedures for greater efficiency. In fact Tcl is implemented as a library of C procedures, as are most Tcl extensions.
You can run extended Tcl interactively using either the tclsh or sgitcl command; see the tclsh(1) or sgitcl(1) reference pages for details. There is no way to run unextended Tcl by itself using the SGITCL facility, and really no reason to do so.