1*b30d1939SAndy Fiddaman 2*b30d1939SAndy Fiddaman KSH-93 VS. KSH-88 3*b30d1939SAndy Fiddaman 4*b30d1939SAndy Fiddaman 5*b30d1939SAndy FiddamanThe following is a list of known incompatibilities between ksh-93 and ksh-88. 6*b30d1939SAndy FiddamanI have not include cases that are clearly bugs in ksh-88. I also have 7*b30d1939SAndy Fiddamanomitted features that are completely upward compatible. 8*b30d1939SAndy Fiddaman 9*b30d1939SAndy Fiddaman1. Functions, defined with name() with ksh-93 are compatible with 10*b30d1939SAndy Fiddaman the POSIX standard, not with ksh-88. No local variables are 11*b30d1939SAndy Fiddaman permitted, and there is no separate scope. Functions defined 12*b30d1939SAndy Fiddaman with the function name syntax, maintain compatibility. 13*b30d1939SAndy Fiddaman This also affects function traces. 14*b30d1939SAndy Fiddaman 15*b30d1939SAndy Fiddaman2. ! is now a reserved word. As a result, any command by that 16*b30d1939SAndy Fiddaman name will no longer work with ksh-93. 17*b30d1939SAndy Fiddaman 18*b30d1939SAndy Fiddaman3. The -x attribute of alias and typeset -f is no longer 19*b30d1939SAndy Fiddaman effective and the ENV file is only read for interactive 20*b30d1939SAndy Fiddaman shells. You need to use FPATH to make function definitions 21*b30d1939SAndy Fiddaman visible to scripts. 22*b30d1939SAndy Fiddaman 23*b30d1939SAndy Fiddaman4. A built-in command named command has been added which is 24*b30d1939SAndy Fiddaman always found before the PATH search. Any script which uses 25*b30d1939SAndy Fiddaman this name as the name of a command (or function) will not 26*b30d1939SAndy Fiddaman be compatible. 27*b30d1939SAndy Fiddaman 28*b30d1939SAndy Fiddaman5. The output format for some built-ins has changed. In particular 29*b30d1939SAndy Fiddaman the output format for set, typeset and alias now have single 30*b30d1939SAndy Fiddaman quotes around values that have special characters. The output 31*b30d1939SAndy Fiddaman for trap without arguments has a format that can be used as input. 32*b30d1939SAndy Fiddaman 33*b30d1939SAndy Fiddaman6. With ksh-88, a dollar sign ($') followed by a single quote was 34*b30d1939SAndy Fiddaman interpreted literally. Now it is an ANSI-C string. You 35*b30d1939SAndy Fiddaman must quote the dollar sign to get the previous behavior. 36*b30d1939SAndy Fiddaman Also, a $ in front of a " indicates that the string needs 37*b30d1939SAndy Fiddaman to be translated for locales other than C or POSIX. The $ 38*b30d1939SAndy Fiddaman is ignored in the C and POSIX locale. 39*b30d1939SAndy Fiddaman 40*b30d1939SAndy Fiddaman7. With ksh-88, tilde expansion did not take place inside ${...}. 41*b30d1939SAndy Fiddaman with ksh-93, ${foo-~} will cause tilde expansion if foo is 42*b30d1939SAndy Fiddaman not set. You need to escape the ~ for the previous behavior. 43*b30d1939SAndy Fiddaman 44*b30d1939SAndy Fiddaman8. Some changes in the tokenizing rules where made that might 45*b30d1939SAndy Fiddaman cause some scripts with previously ambiguous use of quoting 46*b30d1939SAndy Fiddaman to produce syntax errors. 47*b30d1939SAndy Fiddaman 48*b30d1939SAndy Fiddaman9. Programs that rely on specific exit values for the shell, 49*b30d1939SAndy Fiddaman (rather than 0 or non-zero) may not be compatible. The 50*b30d1939SAndy Fiddaman exit status for many shell failures has been changed. 51*b30d1939SAndy Fiddaman 52*b30d1939SAndy Fiddaman10. Built-ins in ksh-88 were always executed before looking for 53*b30d1939SAndy Fiddaman the command in the PATH variable. This is no longer true. 54*b30d1939SAndy Fiddaman Thus, with ksh-93, if you have the current directory first 55*b30d1939SAndy Fiddaman in your PATH, and you have a program named test in your 56*b30d1939SAndy Fiddaman directory, it will be executed when you type test; the 57*b30d1939SAndy Fiddaman built-in version will be run at the point /bin is found 58*b30d1939SAndy Fiddaman in your PATH. 59*b30d1939SAndy Fiddaman 60*b30d1939SAndy Fiddaman11. Some undocumented combinations of argument passing to ksh 61*b30d1939SAndy Fiddaman builtins no longer works since ksh-93 is getopts conforming 62*b30d1939SAndy Fiddaman with respect to its built-ins. For example, typeset -8i 63*b30d1939SAndy Fiddaman previously would work as a synonym for typeset -i8. 64*b30d1939SAndy Fiddaman 65*b30d1939SAndy Fiddaman12. Command substitution and arithmetic expansion are now performed 66*b30d1939SAndy Fiddaman on PS1, PS3, and ENV when they are expanded. Thus, ` and $( 67*b30d1939SAndy Fiddaman as part of the value of these variables must be preceded by a \ 68*b30d1939SAndy Fiddaman to preserve their previous behavior. 69*b30d1939SAndy Fiddaman 70*b30d1939SAndy Fiddaman13. The ERRNO variable has been dropped. 71*b30d1939SAndy Fiddaman 72*b30d1939SAndy Fiddaman14. If the file name following a redirection symbol contain pattern 73*b30d1939SAndy Fiddaman characters they will only be expanded for interactive shells. 74*b30d1939SAndy Fiddaman 75*b30d1939SAndy Fiddaman15. The arguments to a dot script will be restored when it completes. 76*b30d1939SAndy Fiddaman 77*b30d1939SAndy Fiddaman16. The list of tracked aliases is not displayed with alias unless 78*b30d1939SAndy Fiddaman the -t option is specified. 79*b30d1939SAndy Fiddaman 80*b30d1939SAndy Fiddaman17. The POSIX standard requires that test "$arg" have exit status 81*b30d1939SAndy Fiddaman of 0, if and only if $arg is null. However, since this breaks 82*b30d1939SAndy Fiddaman programs that use test -t, ksh-93 treats an explicit test -t 83*b30d1939SAndy Fiddaman as if the user had entered test -t 1. 84*b30d1939SAndy Fiddaman 85*b30d1939SAndy Fiddaman18. The ^T directive of emacs mode has been changed to work the 86*b30d1939SAndy Fiddaman way it does in gnu-emacs. 87*b30d1939SAndy Fiddaman 88*b30d1939SAndy Fiddaman19. ksh-88 allowed unbalanced parenthes within ${name op val} whereas 89*b30d1939SAndy Fiddaman ksh-93 does not. Thus, ${foo-(} needs to be written as ${foo-\(} 90*b30d1939SAndy Fiddaman which works with both versions. 91*b30d1939SAndy Fiddaman 92*b30d1939SAndy Fiddaman20. kill -l in ksh-93 lists only the signal names, not their numerical 93*b30d1939SAndy Fiddaman values. 94*b30d1939SAndy Fiddaman 95*b30d1939SAndy Fiddaman21. Local variables defined by typeset are statically scoped in 96*b30d1939SAndy Fiddaman ksh-93. In ksh-88 they were dynamically scoped although this 97*b30d1939SAndy Fiddaman behavior was never documented. 98*b30d1939SAndy Fiddaman 99*b30d1939SAndy Fiddaman22. The value of the variable given to getopts is set to ? when 100*b30d1939SAndy Fiddaman the end-of-options is reached to conform to the POSIX standard. 101*b30d1939SAndy Fiddaman 102*b30d1939SAndy Fiddaman23. Since the POSIX standard requires that octal constants be 103*b30d1939SAndy Fiddaman recongnized, doing arithmetic on typeset -Z variables can 104*b30d1939SAndy Fiddaman yield different results that with ksh-88. Most of these 105*b30d1939SAndy Fiddaman differences were eliminated in ksh-93o. Starting in ksh-93u+, the 106*b30d1939SAndy Fiddaman let command no longer recognizes octal constants starting with 0 107*b30d1939SAndy Fiddaman for compatibility with ksh-88 unless the option letoctal is on. 108*b30d1939SAndy Fiddaman 109*b30d1939SAndy Fiddaman24. Starting after ksh-93l, If you run ksh name, where name does 110*b30d1939SAndy Fiddaman not contain a /, the current directory will be searched 111*b30d1939SAndy Fiddaman before doing a path search on name as required by the POSIX 112*b30d1939SAndy Fiddaman shell standard. 113*b30d1939SAndy Fiddaman 114*b30d1939SAndy Fiddaman25. In ksh-93, cd - will output the directory that it changes 115*b30d1939SAndy Fiddaman to on standard output as required by X/Open. With ksh-88, 116*b30d1939SAndy Fiddaman this only happened for interactive shells. 117*b30d1939SAndy Fiddaman 118*b30d1939SAndy Fiddaman26. As an undocumented feature of ksh-88, a leading 0 to an 119*b30d1939SAndy Fiddaman assignment of an integer variable caused that variable 120*b30d1939SAndy Fiddaman to be treated as unsigned. This behavior was removed 121*b30d1939SAndy Fiddaman starting in ksh-93p. 122*b30d1939SAndy Fiddaman 123*b30d1939SAndy Fiddaman27. The getopts builtin in ksh-93 requires that optstring contain 124*b30d1939SAndy Fiddaman a leading + to allow options to begin with a +. 125*b30d1939SAndy Fiddaman 126*b30d1939SAndy Fiddaman28. In emacs/gmacs mode, control-v will not display the version when 127*b30d1939SAndy Fiddaman the stty lnext character is set to control-v or is unset. 128*b30d1939SAndy Fiddaman The sequence escape control-v will display the shell version. 129*b30d1939SAndy Fiddaman 130*b30d1939SAndy Fiddaman29. In ksh-88, DEBUG traps were executed. after each command. In ksh-93 131*b30d1939SAndy Fiddaman DEBUG traps are exeucted before each command. 132*b30d1939SAndy Fiddaman 133*b30d1939SAndy Fiddaman30. In ksh-88, a redirection to a file name given by an empty string was 134*b30d1939SAndy Fiddaman ignored. In ksh-93, this is an error. 135*b30d1939SAndy FiddamanI am interested in expanding this list so please let me know if you 136*b30d1939SAndy Fiddamanuncover any others. 137