notes

一个开放源代码的 AT&T 的 Korn Shell 的复制品, 支持大多数 ksh89 的特性。

      Illegal instruction (core dumped)
    - (all)
      $ for i in a b c ; do echo $i, ${i[2]}, ${i[10]} ; done
      a, ,
      a, , b
      a, , c
      $ 
    - (all)
      $ echo ${abc:-G { I } K }
      G { I K }
      $ 
      $ abc=hi
      $ echo ${abc:-G { I } K }
      hi K }
      $
      The second echo should only have printed `hi'.
    - (all)
      $ echo ${abc:- > foo}
      syntax error: > unexpected
      $ 
    - (all? hpux) read reads too much from pipe (when pipe isn't stdin)
	print 'hi\nthere' | ksh 8<&0 0< /dev/tty
	    $ read -u8 x
	    $ print $x
	    hi
	    $ cat 0<&8
	    $ read -u8 y
	    $ print $y
	    there
	    $ 
    - (all)
	$ umask 0
	$ umask
	00
	$
    - (osf, mips, !hpux)
	$ exec alias
	alias: not found
	(shell dead)
    - (all) non-white space IFS in non-substitution not preserved
	$ IFS="$IFS:"
	$ echo : "$@"		# this is ok
	:
	$ echo :"$@"		# this should print : too (me thinks)
 
	$ 
    - (only osf/1)
	$ set +m
	$ sleep 1 &		# wait for a sec or two
	$ jobs
	Memory fault (core dumped)
    - (all)
	$ (sleep 1 & echo hi) &
	[1] 123
	$ [1] 234
	hi
    - (osf/1, mips)
	$ getopts abc optc -a -b -c
	$ getopts abc optc -a -b -c
	$ getopts abc optc -a
	Memory fault (core dumped)
    - (osf/1) POSIX says OPTIND shall be initialized to 1
	$ echo $OPTIND
	0
	$ 
    - (osf/1 + others?)
	$ typeset -ri r=10
	$ let r=12
	$ echo $r
	12
	$ 
    - (osf/1 + others?)
	$ typeset -i a
	$ typeset -L3 a
	Memory fault (core dumped)
    - (osf/1 + others?): -L strips leading \ \t\n\r, -R only strips trailing
      spaces
	$ typeset -L3 x
	$ x=' ^I^J^M 2'
	$ echo "($x)"
	(2  )
	$ typeset -R3 y
	$ x='2^I^J^M '
	$ echo "($x)"
	(^I^J^M)
	$ 
    - (osf/1 + others?)
	$ typeset +i RANDOM
	Memory fault (core dumped)
    - (osf/1 + others?): -L/-R/-Z clear -l/-u after assignment and vise versa
	$ typeset -u x=ab
	$ echo "($x)"
	(AB)
	$ typeset -L4 x=def
	$ echo "($x)"
	(DEF )
	$ typeset | grep ' x$'
	leftjust 4 x
	$ 
	$ typeset -L4 x=def
	$ echo "($x)"
	(def )
	$ typeset -u x=ab
	$ echo "($x)"
	(AB  )
	$ typeset | grep ' x$'
	uppercase x
	$ 
	$ typeset -i x
	$ x='2()'
	$ x='()'
	$ x='2(4)'
    - (osf/1, others?)
	$ unset foo
	$ echo "${foo:-"*"}"
	<results of * expansion>
	$ 
    - (osf/1, others?)
	$ alias blah
	blah: alias not found
	$ alias -x blah | grep blah
	blah
	$ type blah
	Memory fault (core dumped)
    - (osf/1, others?)
	$ trap 'echo hi; false' ERR
	$ false
	hi
	hi
	....
	Memory fault (core dumped)
    - (osf/1, others?)
	$ typeset +i ERRNO
	Memory fault (core dumped)
    - (osf/1, others?)
	$ X=abcdef
	$ echo ${X#a{b,c}e}	# does not match {} inside word part of ${..#..}
	abcdefe}
	$
    - (osf/1, others?)
	$ x=f=abcdef
	$ echo ${f#a|abc}
	def
	$ echo ${f#abc|a}
	bcdef
	$ echo ${f#abc|a|d}
	abcdef
	$ 
    - (osf/1, hp-ux, others?)
	$ i() echo hi
	$ typeset -f
	function i
	{
	hi
	$ 
    - (osf/1, others?)
	$ function X {
		echo start of X
		function Y {
			echo in Y
		}
		echo end of X
	}
	$ X
	start of X
	end of X
	$ typeset -f
	function X
	{
		echo start of X
		function Y {
			echo in Y
		}
		echo end of X
	}
	function Y
	{
			echo in Y
		echo end of X
		}
	}
	$ 
    - (osf/1, others?)
	 $ while read x; do print -r "A $x"; done |&
	 [1] 18212
	 $ exec 8<&p
	 $ kill %1
	 Memory fault
    - (osf/1, others?) Error only happens for builtin commands (/bin/echo works)
	 $ while read x; do print -r "A $x"; done |&
	 [1] 18212
	 $ echo hi <&p
	 hi
	 $ echo hi <&p
	 ksh: p: bad file unit number
	 $ while read x; do print -r "A $x"; done |&
	 ksh: process already exists
	 $ 
    - (osf/1, others?) in restricted shells, command -p should not work.
	$ PATH=/tmp ksh -r
	$ print hi | command -p cat -n 
	     1  hi
	$ 
    - (osf/1, others?) error message wrong for autoload files that don't define
      functions
	$ FPATH=/tmp
	$ echo echo hi there > /tmp/aja
	$ aja
	hi there
	ksh: echo:  not found
	$ 
    - (SunOS M-12/28/93d): 
	$ cat -n << X $(
	> echo foo
	> )
	> X
	> echo bar
	)
	./ksh93: X: cannot open [No such file or directory]
	Memory fault (core dumped)

POSIX sh questions (references are to POSIX 1003.2-1992)
	- arithmetic expressions: how are empty expressions treated?
	  (eg, echo $((  ))).  at&t ksh (and now pdksh) echo 0.
	  Same question goes for `test "" -eq 0' - does this generate an error
	  or, if not, what is the exit code?
	- should tilde expansion occur after :'s in the word part of ${..=..}?
	  (me thinks it should)
	- if a signal is received during the execution of a built-in,
	  does the builtin command exit or the whole shell?
	- is it legal to execute last command of pipeline in current
	  execution environment (eg, can "echo foo | read bar" set
	  bar?)
	- what action should be taken if there is an error doing a dup due
	  to system limits (eg, not enough feil destriptors): is this
	  a "redirection error" (in which case a script will exit iff the
	  error occured while executing a special built-in)?
	  IMHO, shell should exit script.  Couldn't find a blanket statement
	  like "if shell encounters an unexpected system error, it shall
	  exit non-interactive scripts"...

POSIX sh bugs (references are to POSIX 1003.2-1992)
	- in vi insert mode, ^W deletes to beginning of line or to the first
	  blank/punct character (para at line 9124, section 3).  This means
	  "foo     ^W" will do nothing.  This is inconsistent with the vi
	  spec, which says delete preceding word including and interceding
	  blanks (para at line 5189, section 5).
	- parameter expansion, section 3.6.2, line 391: `in each case that a
	  value of word is needed (..), word shall be subjected to tilde
	  expansion, parameter expansion, ...'.  Various expansions should not
	  be performed if parameter is in double quotes.
	- the getopts description says assigning OPTIND a value other than 1
	  produces undefined results, while the rationale for getopts suggests
	  saving/restoring the OPTIND value inside functions (since POSIX
	  functions don't do the save/restore automatically).  Restoring
	  OPTIND is kind of dumb since getopts may have been in the middle
	  of parsing a group of flags (eg, -abc).
	- unclear whether arithmetic expressions (eg, $((..))) should
	  understand C integer constants (ie, 0x123, 0177).  at&t ksh doesn't
	  and neither does pdksh.
	- `...` definition (3.6.3) says nothing about backslash followed by
	  a newline, which sh and at&t ksh strip out completely.  e.g.,
		$ show-args `echo 'X
		Y'`
		Number of args: 1
			1: <XY>
		$ 
	  POSIX would indicate the backslash-newline would be preserved.
	- does not say how "cat << ''" is to be treated (illegal, read 'til
	  blank line, or read 'til eof).  at&t ksh reads til eof, bourne shell
	  reads 'til blank line.  pdksh reads 'til blank line.