ptx bug

[utzoo!duke!vax135!ucbvax!ucsfcgl!tef]

There is a bug in the distributed version of ptx (permuted index)
which may cause the program to hang unexpectedly.  The code is a bit
"unusual" as it is, but if an execl to the sort(1) program fails
ptx falls through a switch case statement and a child process ends up
up waiting for itself to exit (forever).  The fix is left to the
interested hacker.