1*4887Schin
2*4887Schin			KSH-93 VS. KSH-88
3*4887Schin
4*4887Schin
5*4887SchinThe following is a list of known incompatibilities between ksh-93 and ksh-88.
6*4887SchinI have not include cases that are clearly bugs in ksh-88.  I also have
7*4887Schinomitted features that are completely upward compatible.
8*4887Schin
9*4887Schin1.	Functions, defined with name() with ksh-93 are compatible with
10*4887Schin	the POSIX standard, not with ksh-88.  No local variables are
11*4887Schin	permitted, and there is no separate scope.  Functions defined
12*4887Schin	with the function name syntax, maintain compatibility.
13*4887Schin	This also affects function traces.
14*4887Schin
15*4887Schin2.	! is now a reserved word.  As a result, any command by that
16*4887Schin	name will no longer work with ksh-93.
17*4887Schin
18*4887Schin3.	The -x attribute of alias and typeset -f is no longer
19*4887Schin	effective and the ENV file is only read for interactive
20*4887Schin	shells.  You need to use FPATH to make function definitions
21*4887Schin	visible to scripts.
22*4887Schin
23*4887Schin4.	A built-in command named command has been added which is
24*4887Schin	always found before the PATH search.  Any script which uses
25*4887Schin	this name as the name of a command (or function) will not
26*4887Schin	be compatible.
27*4887Schin
28*4887Schin5.	The output format for some built-ins has changed.  In particular
29*4887Schin	the output format for set, typeset and alias now have single
30*4887Schin	quotes around values that have special characters.  The output
31*4887Schin	for trap without arguments has a format that can be used as input.
32*4887Schin
33*4887Schin6.	With ksh-88, a dollar sign ($') followed by a single quote was
34*4887Schin	interpreted literally.  Now it is an ANSI-C string.  You
35*4887Schin	must quote the dollar sign to get the previous behavior.
36*4887Schin	Also, a $ in front of a " indicates that the string needs
37*4887Schin	to be translated for locales other than C or POSIX.  The $
38*4887Schin	is ignored in the C and POSIX locale.
39*4887Schin
40*4887Schin7.	With ksh-88, tilde expansion did not take place inside ${...}.
41*4887Schin	with ksh-93, ${foo-~} will cause tilde expansion if foo is
42*4887Schin	not set.  You need to escape the ~ for the previous behavior.
43*4887Schin
44*4887Schin8.      Some changes in the tokenizing rules where made that might
45*4887Schin	cause some scripts with previously ambiguous use of quoting
46*4887Schin	to produce syntax errors.
47*4887Schin
48*4887Schin9.	Programs that rely on specific exit values for the shell,
49*4887Schin	(rather than 0 or non-zero) may not be compatible.  The
50*4887Schin	exit status for many shell failures has been changed.
51*4887Schin
52*4887Schin10.	Built-ins in ksh-88 were always executed before looking for
53*4887Schin	the command in the PATH variable.  This is no longer true.
54*4887Schin	Thus, with ksh-93, if you have the current directory first
55*4887Schin	in your PATH, and you have a program named test in your
56*4887Schin	directory, it will be executed when you type test; the
57*4887Schin	built-in version will be run at the point /bin is found
58*4887Schin	in your PATH.
59*4887Schin
60*4887Schin11.	Some undocumented combinations of argument passing to ksh
61*4887Schin	builtins no longer works since ksh-93 is getopts conforming
62*4887Schin	with respect to its built-ins.  For example, typeset -8i
63*4887Schin	previously would work as a synonym for typeset -i8.
64*4887Schin
65*4887Schin12.	Command substitution and arithmetic expansion are now performed
66*4887Schin	on PS1, PS3, and ENV when they are expanded.  Thus,  ` and $(
67*4887Schin	as part of the value of these variables must be preceded by a \
68*4887Schin	to preserve their previous behavior.
69*4887Schin
70*4887Schin13.	The ERRNO variable has been dropped.
71*4887Schin
72*4887Schin14.	If the file name following a redirection symbol contain pattern
73*4887Schin	characters they will only be expanded for interactive shells.
74*4887Schin
75*4887Schin15.	The arguments to a dot script will be restored when it completes.
76*4887Schin
77*4887Schin16.	The list of tracked aliases is not displayed with alias unless
78*4887Schin	the -t option is specified.
79*4887Schin
80*4887Schin17.	The POSIX standard requires that test "$arg" have exit status
81*4887Schin	of 0, if and only if $arg is null.  However, since this breaks
82*4887Schin	programs that use test -t, ksh93 treats an explicit test -t
83*4887Schin	as if the user had entered test -t 1.
84*4887Schin
85*4887Schin18.	The ^T directive of emacs mode has been changed to work the
86*4887Schin	way it does in gnu-emacs.
87*4887Schin
88*4887Schin19.	ksh-88 allowed unbalanced parenthes within ${name op val} whereas
89*4887Schin	ksh-93 does not.  Thus, ${foo-(} needs to be written as ${foo-\(}
90*4887Schin	which works with both versions.
91*4887Schin
92*4887Schin20.     kill -l in ksh-93 lists only the signal names, not their numerical
93*4887Schin	values.
94*4887Schin
95*4887Schin21.	Local variables defined by typeset are statically scoped in
96*4887Schin	ksh93.  In ksh88 they were dynamically scoped although this
97*4887Schin	behavior was never documented.
98*4887Schin
99*4887Schin22.	The value of the variable given to getopts is set to ? when
100*4887Schin	the end-of-options is reached to conform to the POSIX standard.
101*4887Schin
102*4887Schin23.	Since the POSIX standard requires that octal constants be
103*4887Schin	recongnized, doing arithmetic on typeset -Z variables can
104*4887Schin	yield different results that with ksh88.  Most of these
105*4887Schin	differences were eliminated in ksh93o.
106*4887Schin
107*4887Schin24.	Starting after ksh93l, If you run ksh name, where name does
108*4887Schin	not contain a /, the current directory will be searched
109*4887Schin	before doing a path search on name as required by the POSIX
110*4887Schin	shell standard.
111*4887Schin
112*4887Schin25.	In ksh93, cd - will output the directory that it changes
113*4887Schin	to on standard output as required by X/Open.  With ksh88,
114*4887Schin	this only happened for interactive shells.
115*4887Schin
116*4887Schin26.	As an undocumented feature of ksh-88, a leading 0 to an
117*4887Schin	assignment of an integer variable caused that variable
118*4887Schin	to be treated as unsigned.  This behavior was removed
119*4887Schin	starting in ksh93p.
120*4887Schin
121*4887Schin27.	The getopts builtin in ksh93 requires that optstring contain
122*4887Schin	a leading + to allow options to begin with a +.
123*4887Schin
124*4887Schin28.	In emacs/gmacs mode, control-v will not display the version when
125*4887Schin	the stty lnext character is set to control-v or is unset.
126*4887Schin	The sequence escape control-v will display the shell version.
127*4887Schin
128*4887SchinI am interested in expanding this list so please let me know if you
129*4887Schinuncover any others.
130