Version 4 of eof

eof is, in one sense, a command:

and, in another sense, an acronym for End Of File.

Programmers can use eof to determine whether the channel has reached the end of input.

Note that it fires only after the last successful gets, so testing for a -1 return value on gets may be a better idea:

 while {[gets $fp line]>=0} {...}

instead of

 while {![eof $fp]} {
    gets $fp line
    if [eof $fp break] ;# otherwise loops one time too many
    ...
 } ;# RS

Can anyone indicate whether there are certain types of channels (pipe, socket, etc.) where eof doesn't do what one might at first blush expect?