pgtksh is a Tcl/Tk shell interface extended with Postgres database access functions. (Essentially, it is wish with libpgtcl loaded.) Like with wish, the regular Tcl/Tk shell, the first command line argument is a script file, any remaining arguments are passed to the script. Special options may be processed by the X Window System libraries instead. If no script file is named, the shell is interactive.
A plain Tcl shell with Postgres functions is available as pgtclsh .
Read the upstream documentation. For corrections, first check the current manual.