execline
Software
skarnet.org
 The ifte program 
ifte performs a conditional alternative.
 Interface 
 In an execlineb script:
     ifte [ -X ] [ -n ] { progthen... } { progelse... } progif...
 -  ifte reads progthen... and progelse... in two
consecutive blocks. 
-  ifte runs progif... as a child process
and waits for it to complete. 
-  If progif... crashes (i.e. is killed by a signal), ifte
prints an error message, then exits 128 plus the number of the signal that
killed progif. 
-  If progif... exits zero, ifte execs into
progthen..., else it execs into progelse.... 
 Options 
 -  -X : do not exit if progif crashes; instead,
proceed as if the test had returned false. 
-  -n : negate the test. progthen... will be run
iff progif... exits nonzero. 
 Notes 
 ifte is a simpler version of ifthenelse.
It performs only conditional execution, not instruction sequence.
"ifthenelse { progif } { progthen } { progelse } remainder" is the
equivalent of "foreground { ifte { progthen } { progelse } progif } remainder".