1 2 KSH-93 VS. KSH-88 3 4 5The following is a list of known incompatibilities between ksh-93 and ksh-88. 6I have not include cases that are clearly bugs in ksh-88. I also have 7omitted features that are completely upward compatible. 8 91. Functions, defined with name() with ksh-93 are compatible with 10 the POSIX standard, not with ksh-88. No local variables are 11 permitted, and there is no separate scope. Functions defined 12 with the function name syntax, maintain compatibility. 13 This also affects function traces. 14 152. ! is now a reserved word. As a result, any command by that 16 name will no longer work with ksh-93. 17 183. The -x attribute of alias and typeset -f is no longer 19 effective and the ENV file is only read for interactive 20 shells. You need to use FPATH to make function definitions 21 visible to scripts. 22 234. A built-in command named command has been added which is 24 always found before the PATH search. Any script which uses 25 this name as the name of a command (or function) will not 26 be compatible. 27 285. The output format for some built-ins has changed. In particular 29 the output format for set, typeset and alias now have single 30 quotes around values that have special characters. The output 31 for trap without arguments has a format that can be used as input. 32 336. With ksh-88, a dollar sign ($') followed by a single quote was 34 interpreted literally. Now it is an ANSI-C string. You 35 must quote the dollar sign to get the previous behavior. 36 Also, a $ in front of a " indicates that the string needs 37 to be translated for locales other than C or POSIX. The $ 38 is ignored in the C and POSIX locale. 39 407. With ksh-88, tilde expansion did not take place inside ${...}. 41 with ksh-93, ${foo-~} will cause tilde expansion if foo is 42 not set. You need to escape the ~ for the previous behavior. 43 448. Some changes in the tokenizing rules where made that might 45 cause some scripts with previously ambiguous use of quoting 46 to produce syntax errors. 47 489. Programs that rely on specific exit values for the shell, 49 (rather than 0 or non-zero) may not be compatible. The 50 exit status for many shell failures has been changed. 51 5210. Built-ins in ksh-88 were always executed before looking for 53 the command in the PATH variable. This is no longer true. 54 Thus, with ksh-93, if you have the current directory first 55 in your PATH, and you have a program named test in your 56 directory, it will be executed when you type test; the 57 built-in version will be run at the point /bin is found 58 in your PATH. 59 6011. Some undocumented combinations of argument passing to ksh 61 builtins no longer works since ksh-93 is getopts conforming 62 with respect to its built-ins. For example, typeset -8i 63 previously would work as a synonym for typeset -i8. 64 6512. Command substitution and arithmetic expansion are now performed 66 on PS1, PS3, and ENV when they are expanded. Thus, ` and $( 67 as part of the value of these variables must be preceded by a \ 68 to preserve their previous behavior. 69 7013. The ERRNO variable has been dropped. 71 7214. If the file name following a redirection symbol contain pattern 73 characters they will only be expanded for interactive shells. 74 7515. The arguments to a dot script will be restored when it completes. 76 7716. The list of tracked aliases is not displayed with alias unless 78 the -t option is specified. 79 8017. The POSIX standard requires that test "$arg" have exit status 81 of 0, if and only if $arg is null. However, since this breaks 82 programs that use test -t, ksh93 treats an explicit test -t 83 as if the user had entered test -t 1. 84 8518. The ^T directive of emacs mode has been changed to work the 86 way it does in gnu-emacs. 87 8819. ksh-88 allowed unbalanced parenthes within ${name op val} whereas 89 ksh-93 does not. Thus, ${foo-(} needs to be written as ${foo-\(} 90 which works with both versions. 91 9220. kill -l in ksh-93 lists only the signal names, not their numerical 93 values. 94 9521. Local variables defined by typeset are statically scoped in 96 ksh93. In ksh88 they were dynamically scoped although this 97 behavior was never documented. 98 9922. The value of the variable given to getopts is set to ? when 100 the end-of-options is reached to conform to the POSIX standard. 101 10223. Since the POSIX standard requires that octal constants be 103 recongnized, doing arithmetic on typeset -Z variables can 104 yield different results that with ksh88. Most of these 105 differences were eliminated in ksh93o. 106 10724. Starting after ksh93l, If you run ksh name, where name does 108 not contain a /, the current directory will be searched 109 before doing a path search on name as required by the POSIX 110 shell standard. 111 11225. In ksh93, cd - will output the directory that it changes 113 to on standard output as required by X/Open. With ksh88, 114 this only happened for interactive shells. 115 11626. As an undocumented feature of ksh-88, a leading 0 to an 117 assignment of an integer variable caused that variable 118 to be treated as unsigned. This behavior was removed 119 starting in ksh93p. 120 12127. The getopts builtin in ksh93 requires that optstring contain 122 a leading + to allow options to begin with a +. 123 12428. In emacs/gmacs mode, control-v will not display the version when 125 the stty lnext character is set to control-v or is unset. 126 The sequence escape control-v will display the shell version. 127 128I am interested in expanding this list so please let me know if you 129uncover any others. 130