fish 3.0b1

fish 3.0 is a major release which brings with it both improvements in functionality and some breaking changes. All fish scripts should be reviewed

Deprecations

• The IFS variable is deprecated and will be removed in fish 4.0 (#4156).
• The function --on-process-exit event will be removed in future (#4700). Use the fish_exit event instead.
• $_ is deprecated and will removed in the future (#813). Use status current-command in a subshell instead.
• ^ as a redirection deprecated and will be removed in the future. (#4394). Use 2> to redirect stderr. This is controlled by the stderr-nocaret feature flag.
• ? as a glob is deprecated and will be removed in the future. (#4520). This is controlled by the qmark-noglob feature flag.

Notable non-backward compatible changes

• % is no longer used for process and job expansion. $fish_pid and $last_pid have taken the place of %self and %last respectively. Some commands have been wrapped to still understand process expansion, including bg, fg and kill (#4230, #1202)
• A literal {} now expands to itself, rather than nothing. This makes working with find -exec easier. (#1109, #4632)
• Successive commas in brace expansions are handled in less surprising manner ({,,,} expands to four empty strings rather than an empty string, a comma and an empty string again). (#3002, #4632).
• for loop control variables are no longer local to the for block (#1935).
• Variables set in if and while conditions are available outside the block (#4820).
• Local exported (set -lx) vars are now visible to functions (#1091).
• set x[1] x[2] a b is no longer valid syntax (#4236).
• The new math builtin (see below) does not support logical expressions; test should be used instead (#4777).
• Range expansion ($foo[1..5]) will now always go forward if only the end is negative, and in reverse if just the start is. This is to enable clamping to the last valid index without changing direction if the list has fewer elements than expected.
• Background jobs not first disown'd will be reaped upon exec, bringing the behavior in line with that of exit.
• read now uses -s as short for --silent (à la bash); --shell's abbreviation (formerly -s) is now -S instead (#4490).

Notable fixes and improvements

Syntax/semantic changes and new builtins

• fish now supports &&, ||, and ! (#4620).
• Variables may be used as commands (#154).
• A new feature flags mechanism is added for staging deprecations and breaking changes. Feature flags may be specified at launch with fish --features ... or by setting the universal fish_features variable. (#4940)
• wait builtin is added for waiting on processes (#4498).
• math is now a builtin rather than a wrapper around bc (#3157). The default scale is now 6, so that floating point computations produce decimals (#4478).
• Using a read-only variable in a for loop is now an error. Note that this never worked. It simply failed to set the for loop var and thus silently produced incorrect results (#4342).
• Arguments to end are now errors, instead of being silently ignored.
• Setting $PATH no longer warns on non-existent directories, allowing for a single $PATH to be shared across machines (e.g. via dotfiles).
• A pipe at the end of a line now allows the job to continue on the next line (#1285).
• The names argparse, read, set, status, test and [ are now reserved and not allowed as function names. This prevents users unintentionally breaking stuff (#3000).
• while sets $status to a more useful value (#4982)
• Command substitution output is now limited to 10 MB by default (#3822).

New features in builtins

• read has a new --delimiter option as a better alternative to the IFS variable (#4256).
• read writes directly to stdout if called without arguments (#4407)
• read can now read one or more individual lines from the input stream without consuming the input in its entirety via read -L/--line. Refer to the read documentation for more info.
• set has a new --append and --prepend option (#1326).
• set has a new --show option to show lots of information about variables (#4265).
• complete now has a -k and --keep-order option to keep the order of the OPTION_ARGUMENTS (#361).
• history search supports globs for wildcard searching (#3136).
• bind has a new --silent option to ignore bind requests for named keys not available under the current $TERMINAL (#4188, #4431).
• string split supports -n/--no-empty to exclude empty strings from the result (#4779).
• funced now has a -s and --save option to automatically save the edited function after successfully editing (#4668).
• exec now triggers the same safety features as exit and prompts for confirmation if background jobs are running.
• The machine hostname, where available, is now exposed as $hostname which is now a reserved variable. This drops the dependency on the hostname executable (#4422).
• The jobs builtin now has a -q and --quiet option to silence the output.
• functions --handlers can be used to show event handlers (#4694).
• alias now has a -s and --save option to save the function generated by the alias using funcsave (#4878).
• The string builtin has new commands split0 and join0 for working with NUL-delimited output.
• The -d option to functions to set the description of an existing function now works; before 3.0 it was documented but unimplemented. Note that the long form --description continues to work. (#5105)
• test and [ now support floating point values in numeric comparisons.

Performance improvements

• abbr has been reimplemented to be faster. This means the old fish_user_abbreviations variable is ignored (#4048).
• Setting variables is much faster (#4200, #4341).
• Globs are faster (#4579).
• string reads from stdin faster (#4610).
• Slicing $history (in particular, $history[1] for the last executed command) is much faster.

Interactive improvements and completions

• cd tab completions no longer descend into the deepest unambiguous path (#4649).
• sudo completions now provide completions for the target of the sudo command.
• Pager navigation has been improved. Most notably, moving down now wraps around, moving up from the commandline now jumps to the last element and moving right and left now reverse each other even when wrapping around (#4680).
• Typing normal characters while the completion pager is active no longer shows the search field. Instead it enters them into the command line, and ends paging (#2249).
• A new input binding pager-toggle-search toggles the search field in the completions pager on and off. By default this is bound to control-s.
• The pager will now show the full command instead of just its last line if the number of completions is large (#4702).
• Tildes in file names are now properly escaped in completions (#2274).
• Wrapping completions (from complete -w or function -w) can now inject arguments. For example, complete gco -w 'git checkout' now works properly (#1976). The alias function has been updated to respect this behavior.
• The universal variables file no longer contains the MAC address. It is now at the fixed location .config/fish/fish_universal_variables (#1912).
• Path completions now support expansions, meaning expressions like python ~/<TAB> now provides file suggestions just like any other relative or absolute path. (This includes support for other expansions, too.)
• Autosuggestions try to avoid arguments that are already present in the command line.
• Added completions for
  • bd (#4472)
  • bower
  • configure (autoconf only)
  • doas
  • hjson
  • j (autojump #4344)
  • jhipster (#4472)
  • kldload
  • kldunload
  • meson
  • ngrok (#4642)
  • optipng
  • port
  • serve (#5026)
  • ttx
  • unzip
  • xsv
• Lots of improvements to completions (especially git and hg).
• Completions for yarn and npm now require the all-the-package-names NPM package for full functionality.
• Completions for bower and yarn now require the jq utility for full functionality.
• Improved French translations.