The ksh(1) man page says that PPID should be a read-only variable.
This diff makes that happen. It does not work to combine the two
lines into "typeset -ir PPID" as the following session demonstrates:
$ NUM=42
$ typeset -ir NUM
ksh: NUM: is read only
Curiously, I did this right the first time and tested it, but before
submitting it yesterday I changed it to the incorrect typeset -ir and
apparently failed to retest. I also submitted it from the command line
with the title "ksh ${PPID} should be read-only" and my shell helpfully
replaced ${PPID} with 641.
This change works correctly and hopefully has a correct subject line.
Index: main.c
===================================================================
RCS file: /cvs/src/bin/ksh/main.c,v
retrieving revision 1.79
diff -u -p -r1.79 main.c
--- main.c 4 Mar 2016 15:11:06 -0000 1.79
+++ main.c 28 May 2016 20:37:25 -0000
@@ -85,6 +85,7 @@ static const char *initcoms [] = {
"typeset", "-r", "KSH_VERSION", NULL,
"typeset", "-x", "SHELL", "PATH", "HOME", NULL,
"typeset", "-i", "PPID", NULL,
+ "typeset", "-r", "PPID", NULL,
"typeset", "-i", "OPTIND=1", NULL,
"eval", "typeset -i RANDOM MAILCHECK=\"${MAILCHECK-600}\"
SECONDS=\"${SECONDS-0}\" TMOUT=\"${TMOUT-0}\"", NULL,
"alias",
