History of Yash

 Legend:
   +: new feature
   -: removed feature
   =: specification change
   *: bug fix
   x: new bug

----------------------------------------------------------------------
Yash 2.40

  =  The "unset" built-in no longer rejects variable names containing
     the "=" symbol as an error. They are now silently ignored.
  =  In the POSIXly-correct mode, unclosed here-documents are now
     treated as an error.
  *  Fixed possible arithmetic overflow errors in memory allocation
     which might result in an undefined behavior.
  *  Fixed crash on assigning a floating-point number in arithmetic
     expansion.
  *  Fixed memory leak on finding a command in a relative path from
     $PATH.
  *  The parameter expansion ${foo##bar*} was being treated like
     ${foo##bar} where the asterisk should match up to the end of the
     parameter value.
  *  The parameter expansion ${foo%%*} was being expanded to ${foo}
     where it should expand to an empty string.
  *  The "getopts" built-in no longer rejects digits as option
     characters.
  *  The non-interactive shell no longer exits when the "command"
     built-in executes the "." built-in and the script is not found.
  *  Fixed incorrect exit status of simple commands where command
     substitution is performed during command word expansion which
     yields no command line words.
  *  The "exec" built-in now correctly exits with an exit status of
     127 for a script file not found.
  *  Pipes were not being connected as expected during command word
     expansion.
  *  The "fg" and "bg" built-ins now report an error when they fail to
     print the job name.

----------------------------------------------------------------------
Yash 2.39

  +  New options for the "read" built-in: -e, -P, -p
  +  New completion script for: passwd, valgrind
  -  The configuration option '--disable-alias' has been dropped.
  =  The "read" built-in now requires the -e (--line-editing) option
     to enable line-editing.
  =  The behavior of the "trap" built-in now conforms to POSIX.1-2013.
     The built-in prints the traps for the calling shell rather than
     the subshell when it is executed in a command substitution.
  =  The manual for the "return" built-in has been clarified as to
     what the built-in can return from. The behavior of the built-in
     has been modified accordingly. It no longer interrupts the "eval"
     and "fc" built-ins.
  *  Crash on division by zero with the "/=" or "%=" operator
     in arithmetic expansion.
  *  Crash in the "complete" built-in called without the -D option.
  *  Yash no longer tries to find the profile and rcfile scripts in
     the root directory when $HOME is not set.
  *  The "read" built-in with a single operand was failing to trim
     initial IFS whitespaces in field splitting.
  *  The "read" built-in was not handling backslashes correctly in
     field splitting if $IFS contained a backslash.
  *  The "-o allexport" option was being ignored when an array is
     assigned by the "read" built-in with the -A option.
  *  Traps are no longer handled while waiting for input with line-
     editing in the "read" built-in.
  *  Operands to the "set" built-in are now correctly completed.
  *  Minor fix in completion script for "git-svn".

----------------------------------------------------------------------
Yash 2.38

  +  New completion scripts for: git-rm
  =  In the POSIXly-correct mode, functions must now be defined with a
     portable name.
  *  Backslashes following IFS characters were wrongly being dropped
     in field splitting.
  *  In the POSIXly-correct mode, non-portable variable names are no
     longer allowed in for loops.
  *  Completion error on words following a tilde expansion.
  *  Completion error on moved or copied tracked files for git-add and
     git-commit.
  *  Completion error on untracked file for git-commit.

----------------------------------------------------------------------
Yash 2.37

  +  Updated completion scripts for:
     git-checkout (Git 2.1.2), git-push (Git 2.0.1), git-submodule
     (Git 2.1.2).

----------------------------------------------------------------------
Yash 2.36

  +  New completion scripts for: git-describe, tig.
  +  Updated completion script for: git-branch (Git 1.9.0).

----------------------------------------------------------------------
Yash 2.35

  +  '--traceall' option.
  +  New completion scripts for:
     git-clean, git-grep, git-ls-remote, git-submodule,
     git-whatchanged
  +  Updated completion scripts for:
     git-cherry-pick, git-rebase (Git 1.8.1.4),
     ssh, ssh-add, ssh-keygen (OpenSSH 6.2)
  =  The condition for exiting the shell when the -e option is enabled
     has been changed in accordance with the 2013 edition of
     POSIX.1-2008.
  =  The "++" and "--" operators are no longer supported in the
     POSIXly-correct mode.
  =  The $RANDOM variable now always returns random numbers, ignoring
     the value from the environment variable, if any.
  =  If yash encounters a too long line that cannot be handled while
     reading a history file, it now tries to keep reading the rest of
     the file rather than stopping reading.
  =  Very long command lines are no longer saved in the history file.
  *  Minor fix in a syntax error message.
  *  Minor fix in completion script for "git", "ssh" and "rsync".

----------------------------------------------------------------------
Yash 2.34

  +  New "test" built-in operator: =~, -o (unary)
  +  New completion scripts for:
     configure, git-name-rev, git-request-pull, make, rsync
  =  A syntax error or expansion error in .yash_profile or .yashrc
     no longer makes the shell exit even when the shell is not
     interactive.
  =  In line-editing, overwritten characters are now restored when you
     hit the backspace key.
  =  In line-editing, the undo history is no longer saved for each
     backspace.
  *  Fixes in completion scripts for "git".

----------------------------------------------------------------------
Yash 2.33

  =  The "help" built-in now prints brief usage of built-ins.
  =  Some error messages for command syntax error have been revised.
  =  Some built-ins now check command syntax more strictly.
  *  The "set" built-in aborts the shell on a command syntax error
     as specified in POSIX.

----------------------------------------------------------------------
Yash 2.32

  +  Man page and HTML manual in English and Japanese.
  =  The "help" built-in now prints part of the man page.
  *  Fixes in completion scripts for "git".

----------------------------------------------------------------------
Yash 2.31

  +  Completion of directory stack indices in extended tilde
     expansion.
  +  New option for the "complete" built-in: --dirstack-index
  +  Completion for "svn" version 1.7.
  *  Fixes in "git", "tar" and "su" completion scripts.

----------------------------------------------------------------------
Yash 2.30

  *  Fixed pathname completion for redirections.
  +  New completion scripts for:
     svn, git, gitg, gitk, and gitx.
  *  Minor fixes in completion scripts.

----------------------------------------------------------------------
Yash 2.29

  +  An alias value now can contain newlines.
  *  Fixed invalid memory access on printing an empty array using the
     "typeset" built-in.
  *  The function body is now correctly executed in a subshell when
     the body is defined using the (...) compound command.
  *  In line-editing, the undo command can now be applied only to the
     history entry that is being edited.

----------------------------------------------------------------------
Yash 2.28

  =  In an interactive shell, mail check is now done before job status
     report.
  *  Fixed arithmetic expansion evaluating some expressions that
     should not be evaluated.
  *  Fixed the "array" built-in removing the wrong elements when
     positive and negative indices are intermixed with the -d option.
  *  Fixed the EXIT trap being wrongly executed after a command-not-
     found error.
  *  The EXIT trap is now executed with the correct redirection when
     the last command had redirection.
  *  The "exec" built-in now correctly exports arrays that are just
     assigned.
  *  ${#@} is now correctly expanded to an array of integers that
     represent the lengths of array elements.
  *  Fixed infinite loop in sequential brace expansion.
  *  Fixed configuration file parsing in completion of the "ssh"
     command.
  *  The "-T" option of the "ln" and "mv" commands now can be
     completed.
  *  The EXIT trap now can be completed.

----------------------------------------------------------------------
Yash 2.27

  *  Minor bug fixes.
  +  New completion scripts for:
     awk, chsh, gawk, nawk, pgawk, scp, sftp, ssh-add, ssh-agent,
     ssh-keygen, su, sudo, sudoedit, and useradd.
  *  Fix in completion scripts for the "set" and "tar" commands.

----------------------------------------------------------------------
Yash 2.26

  +  New option for the "return" built-in: -n (--no-return)
  =  Error messages have been revised.
  =  Shell option names have been generalized: Option names are now
     case-insensitive. Non-alphanumeric characters are ignored in
     option names. Options can be inverted by prefixing "no" to
     their names.
  =  "case foo in (esac) bar; esac" is now rejected in the POSIXly
     correct mode.
  =  The "-o noexec" option is now ignored in an interactive shell.
  =  New mail notification is now printed only when the mailbox file
     is not empty.
  =  "printf %c ''" now prints nothing as "printf %c" do.
  =  In an invocation of the "complete" built-in with the -A or -R
     option, the pattern is now matched against the last component of
     the pathname when generating pathname candidates with the -f
     option.
  *  Function names containing an '=' sign can now be specified as
     arguments to the typeset and unset built-ins (with the -f
     option).
  *  Fixed the exit status of iterative execution that was interrupted
     by SIGINT.
  +  New completion scripts for:
     bsdtar, eview, evim, gex, gnutar, gtar, return, rgview, rgvim,
     rview, rvim, slogin, ssh, tar, and which.
  *  Many fixes in completion scripts for:
     bash, chmod, dash, less, mksh, set, sh, and umask.

----------------------------------------------------------------------
Yash 2.25

  =  In the completion candidate list, options are now sorted case-
     insensitively.
  =  While executing a completion function, the $IFS is reset to the
     default value.
  +  New completion scripts for:
     bash, csplit, dash, diff, ed, egrep, env, ex, expand, fgrep,
     file, find, fold, getconf, grep, gview, gvim, gvimdiff, head,
     iconv, id, join, ksh, less, ln, locale, man, mesg, mkdir, mkfifo,
     mksh, more, mv, newgrp, nice, nl, nohup, od, paste, patch,
     pathchk, pr, ps, renice, rm, rmdir, sed, sh, sort, split, stty,
     tail, tee, time, touch, tr, uname, uniq, vi, view, vim, vimdiff,
     wc, who, xargs, and yash.
  *  Many fixes in completion scripts for:
     cat, cd, chgrp, chmod, chown, cmp, comm, cp, crontab, cut, date,
     df, du, exec, ls, and set.

----------------------------------------------------------------------
Yash 2.24

  +  New option for the "." built-in: -L
  +  New options for the "command" built-in: -a, -f, -k
  -  Removed the -B option for the "command" built-in.
  =  Fixed configuration process so that the shell can handle all
     kinds of signals on FreeBSD.
  =  [line-editing] New command completion mechanism. The "complete"
     built-in now has new syntax and semantics. Completion settings
     are now autoloaded from $YASH_LOADPATH.
  +  New completion scripts for:
     basename, bg, cat, chgrp, chmod, chown, cmp, comm, command, cp,
     crontab, cut, date, df, du, export, popd, pushd, readonly, type,
     ".", and "[".
  =  Revised completion scripts for:
     alias, array, bindkey, break, cd, complete, continue, dirs,
     disown, echo, eval, exec, exit, fc, fg, getopts, hash, help,
     history, jobs, kill, ls, printf, pwd, read, set, suspend, test,
     trap, typeset, ulimit, umask, unalias, unset, and wait.
  -  Removed completion script for the "return" built-in.
  =  Short options now come before long options in a completion
     candidate list.
  *  Symbolic links to non-existent files can now be completed.
  *  Other fixes in command completion.
  *  Fixed invalid memory access on parameter expansion failure in
     redirection.

----------------------------------------------------------------------
Yash 2.23

  *  Traps are no longer handled during completion to avoid messing up
     the display.
  *  Fixed invalid memory access during completion. When the notify
     option is enabled, the shell was wrongly trying to notify the job
     status while executing a candidate generator function.
  *  The "-o verbose" option is now disabled during completion to
     suppress the auto-loaded script being printed.
  *  Fixed completion script for the "kill" built-in.

----------------------------------------------------------------------
Yash 2.22

  +  New "test" built-in operators: -G, -O, -N
  +  Completion settings are now autoloaded from $YASH_COMPPATH.
  +  New completion scripts for:
     alias, array, bindkey, break, cd, complete, continue, dirs,
     disown, echo, eval, exec, exit, fc, fg, getopts, hash, help,
     history, jobs, kill, ls, printf, pwd, read, return, set, suspend,
     test, trap, typeset, ulimit, umask, unalias, unset, and wait.
  *  Fix a bug that was causing a signal received by a just-created
     subshell to be wrongly ignored.
  *  Other bug fixes

----------------------------------------------------------------------
Yash 2.21

  +  Command line completion
  =  In an interactive shell, the value of $LINENO is now reset to 1
     every time a command is input and executed.
  *  The "function" keyword was not recognized by "command -v".
  *  Fixed handling of SIGINT so that the interactive shell properly
     gets back to normal after receiving SIGINT.
  *  Input reading functions rewritten, including some bug fixes.

----------------------------------------------------------------------
Yash 2.20

  +  Function definition using the "function" keyword.
  =  The "-nt" and "-ot" operators of the "test" built-in now consider
     a non-existent file older in favor of Korn shell.
  =  [line-editing] some editing commands have been renamed:
       vi-change-all -> vi-change-line
       vi-yank-and-change-all -> vi-yank-all-change-line
       vi-append-end -> vi-append-to-eol
  *  [line-editing] the clear-and-redraw-all command was broken.

----------------------------------------------------------------------
Yash 2.19

  +  The "ulimit" built-in is now available on FreeBSD.
  +  In mail checking, the timestamp of the mail file is now compared
     by the nanosecond if possible.
  +  [line-editing] new line-editing commands:
        oldest-history-bol, newest-history-bol, return-history-bol,
        prev-history-bol, next-history-bol,
        beginning-search-forward, beginning-search-backward
  =  Faster filename pattern matching.
  =  [line-editing] the "accept-line" command no longer accepts a
     failing history search result.
  =  [line-editing] the following commands have been changed not to
     move the cursor to the beginning of the line:
        oldest-history, newest-history, return-history,
        prev-history, next-history
     The new commands whose names end with "-bol" provide the
     previous behaviors.
  *  Fixed broken output of array assignment traces.
  *  [line-editing] the "vi-edit-and-accept" command now handles the
     count.
  *  [line-editing] fixed the cursor position after the
     search-again-forward/backward command in the emacs-like mode.

----------------------------------------------------------------------
Yash 2.18

  +  New operators for string comparison in the "test" built-in:
     ==, ===, !==, <, <=, >, >=
  +  Operators "-nt" and "-ot" in the "test" built-in now compares the
     modification time by the nanosecond if possible.
  +  '--default-directory' option for the "cd" and "pushd" built-in.
  +  '--remove-duplicates' option for the "pushd" built-in.
  +  The right prompt and the styler prompt.
  +  '--le-alwaysrp' option.
  =  The interpretation of escape sequences to change the font in
     $PS1 and $PS2 has been changed.
  =  $PS3 no longer initialized.
  =  Escape sequences are now interpreted in $PS4 as well as in $PS1
     and $PS2.
  =  The "echo" and "printf" built-ins now can print a null character.
  *  [line-editing] $LINES and $COLUMNS were wrongly ignored.
  *  [line-editing] fixed font color for some terminals.

----------------------------------------------------------------------
Yash 2.17

  +  '--le-visiblebell' option.
  +  New operators for version comparison in the "test" built-in:
     -veq, -vne, -vgt, -vge, -vlt, -vle
  +  [line-editing] "eof" command
  =  The "typeset" built-in now prints only local variables when
     invoked without the -g option or operands.
  =  The "typeset" built-in now prints function definitions in a
     pretty format.
  =  When not in POSIXly-correct mode, commands in command substitu-
     tion are now parsed when the command containing the substitution
     is parsed.
  *  Fixed the parse error on parameter expansion "${#}".
  *  Fixed the "wait" built-in wrongly trying to wait for non-parent
     processes when invoked in a subshell.
  *  [line-editing] vi-replace-char command was broken.
  *  Many other bug fixes

----------------------------------------------------------------------
Yash 2.16

  +  '--curbg' and '--curstop' options.
  =  '--curasync' option is now set by default.
  =  Changed exit status of a while/until loop whose body is empty.
  =  The "return" and "exit" built-ins now accepts an exit status of
     256 or larger.
  =  The "echo" built-in now interprets octal escapes only beginning
     with a backslash followed by a zero.
  *  Fixed a syntax error of a special built-in invoked thru the
     "command" built-in causing the non-interactive shell to exit.
  *  Fixed the exit status of the shell when the EXIT trap is set.
  *  The '--allexport' option was wrongly ignored by the "read" and
     "getopts" built-ins.
  *  Fixed segfaults and other errors in the "getopts" built-in.
  *  [line-editing] Fixed the vi-replace-char command causing invalid
     memory access.
  *  [line-editing] Fixed the emacs-just-one-space command not leaving
     space(s).

----------------------------------------------------------------------
Yash 2.15

  +  An interactive shell now can be interrupted by SIGINT.
  +  Bracket expressions in pathname expansion are now fully supported
     (provided that libc's regex implementation is correct).
  =  The "suspend" built-in now requires the -f option to suspend an
     interactive shell that is a session leader.
  =  The shell no longer automatically sets the $YASH_LE_TIMEOUT
     variable.
  =  A job-control shell now stops itself when invoked in the
     background.
  =  A job-control shell no longer ignores SIGTTOU by default.
  =  The '--nocaseglob' option no longer affects pattern matching in
     parameter expansions of the form "${var#xxx}", "${var%xxx}", etc.
  *  Fixed pathname expansion on redirection target.
  *  Couldn't set a signal handler to the default by the "trap"
     built-in if the signal was ignored on invocation of an inter-
     active shell.
  *  Fixed accidental interruption of built-ins by signals.
  *  Fixed parser so that a non-simple command is properly parsed
     after alias substitution.
  *  Various bug fixes

----------------------------------------------------------------------
Yash 2.14

  +  The -l option for the "bindkey" built-in.
  +  Negative array indices are now allowed.
  =  $PWD is now set to "/" (rather than "/..") after "cd /..".
  =  The "command" built-in with the -vb option now ignores shell
     keywords, aliases and functions.
  =  Most of the built-ins now prints an error message and returns
     non-zero when they cannot print something to the standard output.
  =  The "pwd" and "times" built-ins now fail when an operand is
     given.
  =  The shell no longer exits when an assignment for a special
     built-in failed if not in POSIXly-correct mode.
  *  "cd //" was failing if the current directory is "/".
  *  Invoking the "bindkey" built-in in the yashrc file was causing an
     invalid memory access.
  *  The "command" built-in with the -vb option was failing to find
     regular built-ins that are not in $PATH.
  *  The "dirs" command was going into an infinite loop if given an
     argument.
  *  The -c and -d options are wrongly rejected by the "ulimit"
     built-in.
  *  The "fg" built-in now refuses more than one operands in POSIXly-
     correct mode, as described in the help.

----------------------------------------------------------------------
Yash 2.13

  +  "history" built-in
  +  The -i option for the "eval", "break" and "continue" built-ins.
  +  The value of the $COMMAND_NOT_FOUND_HANDLER variable is now
     executed when a command is not found.
  -  '--autocd' option
  =  The exit status is now one when the "return" built-in is used
     outside a function in an interactive shell.
  =  Revised command search and execution.
  *  The shell would not exit after the "exit" built-in twice in a row
     when you have $PROMPT_COMMAND set and you have stopped jobs.
  *  The "notifyle" option not working with $PROMPT_COMMAND set.
  *  [line-editing] Redoing was broken.
  *  [line-editing] The command line was not redrawn after trap
     handling.
  *  [line-editing] Fixed some bugs in the vi-edit-and-accept command.

----------------------------------------------------------------------
Yash 2.12

  +  Emacs-like line-editing.
  +  "bindkey" built-in.
  +  The $PROMPT_COMMAND variable now can be an array.
  +  The value of the $YASH_AFTER_CD variable is now executed after
     the working directory was changed.
  =  The "fg" and "bg" built-in now always sends SIGCONT to the
     continued job.
  =  The "exit" built-in now warns about stopped jobs even when
     executed after the "fg", "bg", "disown" or "wait" built-in.
  *  In vi-like line-editing, the wrong text was put after 30th yank.
  *  In vi-like line-editing, the "s" command cannot be used if the
     cursor is at the beginning of line

----------------------------------------------------------------------
Yash 2.11

  +  Added the "--histspace" and "--le-noconvmeta" options.
  +  Support for the $HISTRMDUP variable.
  +  Support for the $YASH_LE_TIMEOUT variable.
  +  The "kill" built-in with the "-l" option now accepts signal names
     as operands.
  =  The "--le-convmeta" option now is a Boolean option.
  =  The "$-" special parameter now includes the "l" flag if the
     shell is a login shell.
  *  An empty case command "case i in (*) esac" now always returns the
     exit status of zero.
  *  Quoted words were incorrectly expanded with backslashes when the
     "-f" option is set.
  *  Fixed invalid memory access in the "v" command of vi-like
     line-editing.

----------------------------------------------------------------------
Yash 2.10

  +  History search in line-editing.
  =  Empty lines are no longer stored in the history.
  =  In the vi-like line-editing, "cw" and "cW" now work as in vi.
  *  Setting the "notifyle" option caused a segfault if yash was
     configured with line-editing disabled.
  *  In line-editing, undoing a change to a history entry did not
     restore the cursor position properly.
  *  Some fixes for invalid memory access during line-editing.

----------------------------------------------------------------------
Yash 2.9

  +  Line-editing in the interactive mode.
  x  Line-editing is not fully implemented.
  +  Multiple instances of shell that use the same file for the
     history file now share the history.
  -  The "history" built-in has been removed.
  =  Now non-ASCII alphabets are allowed in variable names.
  =  Now nested parameter expansions must be enclosed by braces.
  =  The "help" built-in now prints an error message if the specified
     built-in is not found.
  *  Fixed floating-point arithmetics in arithmetic expansions.
  *  Fixed parser for arithmetic expansions that was incorrectly
     rejecting identifiers that start with underscores.
  *  Fixed parser that had trouble parsing parameter expansions
     containing the hash sign like "${#=x}".
  *  Fixed the help message for the "pwd" built-in.

----------------------------------------------------------------------
Yash 2.8

  +  Brace expansion with delta: {a..b..c}
  +  The "command" built-in's -b and -B options now can be used with
     the -v and -V options.
  =  Yash now conforms to POSIX.1-2008.
    .  The "read" built-in now always removes trailing white-spaces
       from the input.
    .  The results of tilde expansion are no longer subject to field
       splitting and pathname expansion.
    .  The "pwd" built-in with the -P option no longer sets the $PWD
       variable.
    .  "cd -L foo/.." is no more the same as "cd -L ." in that it is
       an error when the directory "foo" does not exist.
    .  The "command" built-in's -p option now can be used with the -v
       and -V options.
    .  In POSIXly-correct mode, all asynchronous commands now ignore
       SIGINT and SIGQUIT (even when job control is active).
  *  When executing commands edited by the "fc" built-in, the $?
     variable was incorrectly assigned the exit status of the editor
     invoked by "fc".
  *  Backslashes, commas and braces in $IFS were incorrectly ignored
     in field splitting.
  *  Pathname expansion failed if we do not have the read permission
     for the specified directory even when we only need the search
     permission.
  *  The signal mask of commands invoked by the shell now inherits
     that of the shell (except for trapped signals).
  *  The "command" built-in now properly handles directories given as
     the commands when the "autocd" option is on.

----------------------------------------------------------------------
Yash 2.7

  +  Parameter expansion ${array[index]:=value} now allows assignment
     to an empty array element.
  +  Here-string by the "<<<" operator.
  +  New redirection operator ">>|" opens a pipe.
  -  Loop pipes no longer supported.
  =  The $IFS variable is always initialized to the default value when
     the shell is invoked.
  *  The "echo" and "printf" built-ins now print an error message on
     failure.
  *  A quoted period at the beginning of a filename was not properly
     matching during filename expansion.

----------------------------------------------------------------------
Yash 2.6

  +  Added the -q option to the fc built-in.
  +  Compound commands may now contain no commands inside.
  *  "alias -p" now prints commands with proper escape.
  *  In POSIXly-correct mode, a semicolon followed by the identifier
     followed by "for" is now treated as an error.
  *  Global aliases are now allowed after compound commands.
  *  The "fg" and "wait" built-ins were causing invalid memory access
     when the "-o notify" option is enabled.

----------------------------------------------------------------------
Yash 2.5

  =  Redirection of FDs used by the shell is now error.
  *  Some redirection syntax errors were overlooked.
  *  Fixed the "sig.y" test failure.
  *  When an "exec" command with redirections is enclosed in a brace
     with redirections, the redirections to the brace are now properly
     closed after execution.
  *  Fixed parsing error of a comment after the identifier of a for
     statement.

----------------------------------------------------------------------
Yash 2.4

  =  The long option for the -p option of the "jobs" built-in has been
     changed from "--pid-only" to "--pgid-only".
  *  Trap of SIGCHLD, SIGINT, SIGTERM, SIGQUIT, SIGTSTP, SIGTTOU were
     wrongly set to "ignore" in some condition.
  *  Signal handlers for SIGINT, SIGTERM, SIGQUIT, SIGTSTP, SIGTTOU
     were mistakenly reset in some moments.
  *  Fixed the exit status of the "wait" built-in returned when
     interrupted by a signal.
  *  Fixed file access permission test
  *  "command -V xxx/yyy" now prints an error message if "xxx/yyy" is
     not a valid command.

----------------------------------------------------------------------
Yash 2.3

  =  Now changing LC_CTYPE immediately takes effect if the shell is
     interactive and not in the POSIXly-correct mode.
  *  Fixed parameter expansion: empty words are now expanded properly.
  *  Fixed a race condition, which was causing some signals ignored.
  *  Assignments using the typeset/readonly/export built-ins failed to
     update the shell's internal data. This caused the shell to keep
     using the old PATH after the PATH has been changed.

----------------------------------------------------------------------
Yash 2.2

  +  "help", "pushd", "popd" and "dirs" built-ins
  =  The value of $PWD set by the "cd" built-in is fixed. It now has a
     correct value when changing to a relative path from the root
     directory.
  *  Pathname expansion not properly performed for patterns including
     "." or "..".

----------------------------------------------------------------------
Yash 2.1

  +  Array variables
  +  "array", "echo", "printf" and "test" built-ins
  +  The -A option for the "read" built-in
  *  The colon flag in a parameter expansion like "${FOO:-bar}" was
     ignored if the value of the parameter begins with a certain
     character.
  *  The readonly attribute was ignored when an assignment occurs
     against a command invocation
  *  Passing "=" as a name to the "unset" built-in incorrectly unset
     the positional parameters and caused a potential invalid memory
     access.
  *  Field splitting on variable values that consist only of spaces
     produced wrong results.
  *  Test of file access permission now uses the effective user/group
     IDs rather than the real user/group IDs.

----------------------------------------------------------------------
Yash 2.0

  +  "history" built-in
  +  Command redirection
  *  A POSIXly-correct non-interactive shell exits when a particular
     error occurred on a special built-in according to POSIX.
  *  Alias substitution routines were improved.
  *  Other bug fixes

----------------------------------------------------------------------
Yash 2.0 beta2

  +  Command history
  +  "type", "hash" and "fc" built-ins
  =  If the "command" built-in with the -V option fails to find a
     command, an message is printed.
  *  Invocation of an external command with an assignment to the $PATH
     variable caused an invalid memory access.
  *  Single quote not parsed properly in some circumstances.
  *  Other bug fixes

----------------------------------------------------------------------
Yash 2.0 beta1

  +  "read", "getopts" and "command" built-ins
  +  '--autocd' and '--curasync' option
  +  Mail check feature
  +  The prompt command
  =  The "readonly" and "export" built-ins now affects global
     variables by default.
  *  The standard input is no longer buffered
  *  The "typeset" built-in now allows any characters other than '='
     for variable names.
  *  The special parameter $? reflects the exit status of a command
     substitution in a variable assignment.
  *  Many other bug fixes

----------------------------------------------------------------------
Yash 2.0 beta0

  +  "eval", "exec", ".", "times", "umask", "typeset", "export",
     "readonly", "unset", "shift" and "trap" built-ins
  +  "wait" built-in now can be interrupted
  +  Arithmetic expansions
  +  Interactive shell now notifies the process killed by a signal
  -  "/etc/profile" and "~/.profile" are no longer sourced on start-up
  *  Fixed token delimitation in alias substitution
  *  Fixed token delimitation on assignments without values
  *  Many other bug fixes

----------------------------------------------------------------------
Yash 2.0 alpha2

  +  Initialization files such as "/etc/profile" and "~/.yashrc" are
     now sourced on start-up.
  +  '--noprofile', '--norcfile' and '--rcfile' options
  +  "pwd", "set", "exit", "return", "break", "continue", "jobs",
     "fg", "bg", "wait", "disown", "alias" and "unalias" built-ins
  *  '--nocaseglob' was misinterpreted as '-c'.
  *  It was not fully case-insensitive when '--nocaseglob' is on.
  *  If job control is off, an interactive shell no longer prints
     changed status of jobs before prompt.
  =  Error handling for unset parameters was improved.
  =  The help message for 'yash --help' is now much briefer.

----------------------------------------------------------------------
Yash 2.0 alpha1

  +  New options implemented: -x, -h, -a
  =  The default value of 'PS3' is not set in POSIXly-correct mode.
  +  'configure' accepts new '--no-undefined' option
  +  ":", "true", "false", "cd" built-ins
  *  Command hashtable is now cleared when PATH is assigned.
  *  Assertion failure when a null character is input
  *  Many other bug fixes

----------------------------------------------------------------------
Yash 2.0 alpha0 (the first release of version 2.x)

  x  Arithmetic expansion is not implemented
  x  Built-ins are not implemented at all
