Bash-4.2 distribution sources and documentation

NEWS

@@ -1,3 +1,99 @@
+This is a terse description of the new features added to bash-4.2 since
+the release of bash-4.1.  As always, the manual page (doc/bash.1) is
+the place to look for complete descriptions.
+
+1.  New Features in Bash
+
+a.  `exec -a foo' now sets $0 to `foo' in an executable shell script without a
+    leading #!.
+
+b.  Subshells begun to execute command substitutions or run shell functions or
+    builtins in subshells do not reset trap strings until a new trap is
+    specified.  This allows $(trap) to display the caller's traps and the
+    trap strings to persist until a new trap is set.
+
+c.  `trap -p' will now show signals ignored at shell startup, though their
+    disposition still cannot be modified.
+
+d.  $'...', echo, and printf understand \uXXXX and \UXXXXXXXX escape sequences.
+
+e.  declare/typeset has a new `-g' option, which creates variables in the
+    global scope even when run in a shell function.
+
+f.  test/[/[[ have a new -v variable unary operator, which returns success if
+    `variable' has been set.
+
+g.  Posix parsing changes to allow `! time command' and multiple consecutive
+    instances of `!' (which toggle) and `time' (which have no cumulative
+    effect).
+
+h.  Posix change to allow `time' as a command by itself to print the elapsed
+    user, system, and real times for the shell and its children.
+
+j.  $((...)) is always parsed as an arithmetic expansion first, instead of as
+    a potential nested command substitution, as Posix requires.
+
+k.  A new FUNCNEST variable to allow the user to control the maximum shell
+    function nesting (recursive execution) level.
+
+l.  The mapfile builtin now supplies a third argument to the callback command:
+    the line about to be assigned to the supplied array index.
+
+m.  The printf builtin has a new %(fmt)T specifier, which allows time values
+    to use strftime-like formatting.
+
+n.  There is a new `compat41' shell option.
+
+o.  The cd builtin has a new Posix-mandated `-e' option.
+
+p.  Negative subscripts to indexed arrays, previously errors, now are treated
+    as offsets from the maximum assigned index + 1.
+
+q.  Negative length specifications in the ${var:offset:length} expansion,
+    previously errors, are now treated as offsets from the end of the variable.
+
+r.  Parsing change to allow `time -p --'.
+
+s.  Posix-mode parsing change to not recognize `time' as a keyword if the
+    following token begins with a `-'.  This means no more Posix-mode
+    `time -p'.  Posix interpretation 267.
+
+t.  There is a new `lastpipe' shell option that runs the last command of a
+    pipeline in the current shell context.  The lastpipe option has no
+    effect if job control is enabled.
+
+u.  History expansion no longer expands the `$!' variable expansion.
+
+v.  Posix mode shells no longer exit if a variable assignment error occurs
+    with an assignment preceding a command that is not a special builtin.
+
+w.  Non-interactive mode shells exit if -u is enabled and an attempt is made
+    to use an unset variable with the % or # expansions, the `//', `^', or
+    `,' expansions, or the parameter length expansion.
+
+x.  Posix-mode shells use the argument passed to `.' as-is if a $PATH search
+    fails, effectively searching the current directory.  Posix-2008 change.
+
+2.  New Features in Readline
+
+a.  The history library does not try to write the history filename in the
+    current directory if $HOME is unset.  This closes a potential security
+    problem if the application does not specify a history filename.
+
+b.  New bindable variable `completion-display-width' to set the number of
+    columns used when displaying completions.
+
+c.  New bindable variable `completion-case-map' to cause case-insensitive
+    completion to treat `-' and `_' as identical.
+
+d.  There are new bindable vi-mode command names to avoid readline's case-
+    insensitive matching not allowing them to be bound separately.
+
+e.  New bindable variable `menu-complete-display-prefix' causes the menu
+    completion code to display the common prefix of the possible completions
+    before cycling through the list, instead of after.
+
+-------------------------------------------------------------------------------
 This is a terse description of the new features added to bash-4.1 since
 the release of bash-4.0.  As always, the manual page (doc/bash.1) is
 the place to look for complete descriptions.