Opened 3 years ago

Closed 3 years ago

#4404 closed task (fixed)


Reported by: Anton Maisak Owned by: lfs-book
Priority: normal Milestone: 8.4
Component: Book Version: SVN
Severity: normal Keywords:


Change History (2)

comment:1 by Bruce Dubbs, 3 years ago

This is a terse description of the new features added to bash-5.0 since the release of bash-4.4. As always, the manual page (doc/bash.1) is the place to look for complete descriptions.

  1. New Features in Bash
  1. The `wait' builtin can now wait for the last process substitution created.
  1. There is an EPOCHSECONDS variable, which expands to the time in seconds since the Unix epoch.
  1. There is an EPOCHREALTIME variable, which expands to the time in seconds since the Unix epoch with microsecond granularity.
  1. New loadable builtins: rm, stat, fdflags.
  1. BASH_ARGV0: a new variable that expands to $0 and sets $0 on assignment.
  1. When supplied a numeric argument, the shell-expand-line bindable readline command does not perform quote removal and suppresses command and process substitution.
  1. `history -d' understands negative arguments: negative arguments offset from the end of the history list.
  1. The name' argument to the coproc' reserved word now undergoes word expansion, so unique coprocs can be created in loops.
  1. A nameref name resolution loop in a function now resolves to a variable by that name in the global scope.
  1. The wait' builtin now has a -f' option, which signfies to wait until the specified job or process terminates, instead of waiting until it changes state.
  1. There is a define in config-top.h that allows the shell to use a static value for $PATH, overriding whatever is in the environment at startup, for use by the restricted shell.
  1. Process substitution does not inherit the `v' option, like command substitution.
  1. If a non-interactive shell with job control enabled detects that a foreground job died due to SIGINT, it acts as if it received the SIGINT.
  1. The SIGCHLD trap is run once for each exiting child process even if job control is not enabled when the shell is in Posix mode.
  1. A new shopt option: localvar_inherit; if set, a local variable inherits the value of a variable with the same name at the nearest preceding scope.
  1. `bind -r' now checks whether a key sequence is bound before binding it to NULL, to avoid creating keymaps for a multi-key sequence.
  2. A numeric argument to the line editing `operate-and-get-next' command specifies which history entry to use.
  1. The positional parameters are now assigned before running the shell startup files, so startup files can use $@.
  1. There is a compile-time option that forces the shell to disable the check for an inherited OLDPWD being a directory.
  1. The `history' builtin can now delete ranges of history entries using `-d start-end'.
  1. The `vi-edit-and-execute-command' bindable readline command now puts readline back in vi insertion mode after executing commands from the edited file.
  1. The command completion code now matches aliases and shell function names case-insensitively if the readline completion-ignore-case variable is set.
  1. There is a new `assoc_expand_once' shell option that attempts to expand associative array subscripts only once.
  1. The shell only sets up BASH_ARGV and BASH_ARGC at startup if extended debugging mode is active. The old behavior of unconditionally setting them is available as part of the shell compatibility options.
  1. The `umask' builtin now allows modes and masks greater than octal 777.
  1. The `times' builtin now honors the current locale when printing a decimal point.

aa. There is a new (disabled by default, undocumented) shell option to enable

and disable sending history to syslog at runtime.

bb. Bash no longer allows variable assignments preceding a special builtin that

changes variable attributes to propagate back to the calling environment unless the compatibility level is 44 or lower.

cc. You can set the default value for $HISTSIZE at build time in config-top.h.

dd. The `complete' builtin now accepts a -I option that applies the completion

to the initial word on the line.

ee. The internal bash malloc now uses mmap (if available) to satisfy requests

greater than 128K bytes, so free can use mfree to return the pages to the kernel.

ff. The shell doesn't automatically set BASH_ARGC and BASH_ARGV at startup

unless it's in debugging mode, as the documentation has always said, but will dynamically create them if a script references them at the top level without having enabled debugging mode.

gg. The localvar_inherit option will not attempt to inherit a value from a

variable of an incompatible type (indexed vs. associative arrays, for example).

hh. The `globasciiranges' option is now enabled by default; it can be set to

off by default at configuration time.

  1. Associative and indexed arrays now allow subscripts consisting solely of


jj. `checkwinsize' is now enabled by default.

kk. The `localvar_unset' shopt option is now visible and documented.

ll. The `progcomp_alias' shopt option is now visible and documented.

mm. The signal name processing code now understands `SIGRTMIN+n' all the way


nn. There is a new `seq' loadable builtin.

oo. Trap execution now honors the (internal) max invocations of `eval', since

traps are supposed to be executed as if using `eval'.

pp. The $_ variable doesn't change when the shell executes a command that forks.

qq. The `kill' builtin now supports -sSIGNAME and -nSIGNUM, even though

conforming applications aren't supposed to use them.

rr. POSIX mode now enables the `shift_verbose' option.

  1. New Features in Readline
  1. Non-incremental vi-mode search (N', n') can search for a shell pattern, as Posix specifies (uses fnmatch(3) if available).
  1. There are new next-screen-line' and previous-screen-line' bindable commands, which move the cursor to the same column in the next, or previous, physical line, respectively.
  1. There are default key bindings for control-arrow-key key combinations.
  1. A negative argument (-N) to `quoted-insert' means to insert the next N characters using quoted-insert.
  1. New public function: rl_check_signals(), which allows applications to respond to signals that readline catches while waiting for input using a custom read function.
  1. There is new support for conditionally testing the readline version in an inputrc file, with a full set of arithmetic comparison operators available.
  1. There is a simple variable comparison facility available for use within an inputrc file. Allowable operators are equality and inequality; string variables may be compared to a value; boolean variables must be compared to either on' or off'; variable names are separated from the operator by whitespace.
  1. The history expansion library now understands command and process substitution and extended globbing and allows them to appear anywhere in a word.
  1. The history library has a new variable that allows applications to set the initial quoting state, so quoting state can be inherited from a previous line.
  1. Readline now allows application-defined keymap names; there is a new public function, rl_set_keymap_name(), to do that.
  1. The "Insert" keypad key, if available, now puts readline into overwrite mode.

comment:2 by Bruce Dubbs, 3 years ago

Resolution: fixed
Status: newclosed

Fixed at revision 11499.

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