takes the same arguments as eeeexxxxppppeeeecccctttt, however it
returns immediately. Patterns are tested whenever
new input arrives. Note: this only works in the
Tk environment. The pattern ttttiiiimmmmeeeeoooouuuutttt and ddddeeeeffffaaaauuuulllltttt
are meaningless to eeeexxxxppppeeeecccctttt____bbbbaaaacccckkkkggggrrrroooouuuunnnndddd and are
silently discarded. Otherwise, the
eeeexxxxppppeeeecccctttt____bbbbaaaacccckkkkggggrrrroooouuuunnnndddd command uses eeeexxxxppppeeeecccctttt____bbbbeeeeffffoooorrrreeee and
eeeexxxxppppeeeecccctttt____aaaafffftttteeeerrrr patterns just like eeeexxxxppppeeeecccctttt does.
When eeeexxxxppppeeeecccctttt____bbbbaaaacccckkkkggggrrrroooouuuunnnndddd actions are being
evaluated, background processing for the same
spawn id is blocked. Background processing is
unblocked when the action completes. While
background processing is blocked, it is possible
to do a (foreground) eeeexxxxppppeeeecccctttt on the same spawn id.
It is not possible to execute an eeeexxxxppppeeeecccctttt while an
eeeexxxxppppeeeecccctttt____bbbbaaaacccckkkkggggrrrroooouuuunnnndddd is unblocked. eeeexxxxppppeeeecccctttt____bbbbaaaacccckkkkggggrrrroooouuuunnnndddd
for a particular spawn id is deleted by declaring
a new expect_background with the same spawn id.
Declaring eeeexxxxppppeeeecccctttt____bbbbaaaacccckkkkggggrrrroooouuuunnnndddd with no pattern