0.38.0

The output of `tmux -V` starts with "tmux ".

.github/workflows/winget.yml

@@ -0,0 +1,15 @@
+name: Publish to Winget
+on:
+  release:
+    types: [released]
+
+jobs:
+  publish:
+    runs-on: windows-latest # Action can only run on Windows
+    steps:
+      - uses: vedantmgoyal2009/winget-releaser@v2
+        with:
+          identifier: junegunn.fzf
+          version: ${{ github.event.release.tag_name }}
+          installers-regex: '-windows_(armv7|arm64|amd64)\.zip$'
+          token: ${{ secrets.WINGET_TOKEN }}

ADVANCED.md

@@ -1,30 +1,33 @@
 Advanced fzf examples
 ======================
 
-*(Last update: 2022/08/25)*
+* *Last update: 2023/02/15*
+* *Requires fzf 0.38.0 or above*
+
+---
 
 <!-- vim-markdown-toc GFM -->
 
 * [Introduction](#introduction)
 * [Screen Layout](#screen-layout)
-  * [`--height`](#--height)
-  * [`fzf-tmux`](#fzf-tmux)
-    * [Popup window support](#popup-window-support)
+    * [`--height`](#--height)
+    * [`fzf-tmux`](#fzf-tmux)
+        * [Popup window support](#popup-window-support)
 * [Dynamic reloading of the list](#dynamic-reloading-of-the-list)
-  * [Updating the list of processes by pressing CTRL-R](#updating-the-list-of-processes-by-pressing-ctrl-r)
-  * [Toggling between data sources](#toggling-between-data-sources)
+    * [Updating the list of processes by pressing CTRL-R](#updating-the-list-of-processes-by-pressing-ctrl-r)
+    * [Toggling between data sources](#toggling-between-data-sources)
 * [Ripgrep integration](#ripgrep-integration)
-  * [Using fzf as the secondary filter](#using-fzf-as-the-secondary-filter)
-  * [Using fzf as interactive Ripgrep launcher](#using-fzf-as-interactive-ripgrep-launcher)
-  * [Switching to fzf-only search mode](#switching-to-fzf-only-search-mode)
-  * [Switching between Ripgrep mode and fzf mode](#switching-between-ripgrep-mode-and-fzf-mode)
+    * [Using fzf as the secondary filter](#using-fzf-as-the-secondary-filter)
+    * [Using fzf as interactive Ripgrep launcher](#using-fzf-as-interactive-ripgrep-launcher)
+    * [Switching to fzf-only search mode](#switching-to-fzf-only-search-mode)
+    * [Switching between Ripgrep mode and fzf mode](#switching-between-ripgrep-mode-and-fzf-mode)
 * [Log tailing](#log-tailing)
 * [Key bindings for git objects](#key-bindings-for-git-objects)
-  * [Files listed in `git status`](#files-listed-in-git-status)
-  * [Branches](#branches)
-  * [Commit hashes](#commit-hashes)
+    * [Files listed in `git status`](#files-listed-in-git-status)
+    * [Branches](#branches)
+    * [Commit hashes](#commit-hashes)
 * [Color themes](#color-themes)
-  * [Generating fzf color theme from Vim color schemes](#generating-fzf-color-theme-from-vim-color-schemes)
+    * [Generating fzf color theme from Vim color schemes](#generating-fzf-color-theme-from-vim-color-schemes)
 
 <!-- vim-markdown-toc -->
 
@@ -236,15 +239,13 @@ file called `rfv`.
 # 1. Search for text in files using Ripgrep
 # 2. Interactively narrow down the list using fzf
 # 3. Open the file in Vim
-IFS=: read -ra selected < <(
-  rg --color=always --line-number --no-heading --smart-case "${*:-}" |
-    fzf --ansi \
-        --color "hl:-1:underline,hl+:-1:underline:reverse" \
-        --delimiter : \
-        --preview 'bat --color=always {1} --highlight-line {2}' \
-        --preview-window 'up,60%,border-bottom,+{2}+3/3,~3'
-)
-[ -n "${selected[0]}" ] && vim "${selected[0]}" "+${selected[1]}"
+rg --color=always --line-number --no-heading --smart-case "${*:-}" |
+  fzf --ansi \
+      --color "hl:-1:underline,hl+:-1:underline:reverse" \
+      --delimiter : \
+      --preview 'bat --color=always {1} --highlight-line {2}' \
+      --preview-window 'up,60%,border-bottom,+{2}+3/3,~3' \
+      --bind 'enter:become(vim {1} +{2})'
 ```
 
 And run it with an initial query string.
@@ -307,8 +308,12 @@ I know it's a lot to digest, let's try to break down the code.
       position in the window
     - `~3` makes the top three lines fixed header so that they are always
       visible regardless of the scroll offset
-- Once we selected a line, we open the file with `vim` (`vim
-  "${selected[0]}"`) and move the cursor to the line (`+${selected[1]}`).
+- Instead of using shell script to process the final output of fzf, we use
+  `become(...)` action which was added in [fzf 0.38.0][0.38.0] to turn fzf
+  into a new process that opens the file with `vim` (`vim {1}`) and move the
+  cursor to the line (`+{2}`).
+
+[0.38.0]: https://github.com/junegunn/fzf/blob/master/CHANGELOG.md#0380
 
 ### Using fzf as interactive Ripgrep launcher
 
@@ -331,16 +336,14 @@ projects, and it will free up memory as you narrow down the results.
 # 3. Open the file in Vim
 RG_PREFIX="rg --column --line-number --no-heading --color=always --smart-case "
 INITIAL_QUERY="${*:-}"
-IFS=: read -ra selected < <(
-  FZF_DEFAULT_COMMAND="$RG_PREFIX $(printf %q "$INITIAL_QUERY")" \
-  fzf --ansi \
-      --disabled --query "$INITIAL_QUERY" \
-      --bind "change:reload:sleep 0.1; $RG_PREFIX {q} || true" \
-      --delimiter : \
-      --preview 'bat --color=always {1} --highlight-line {2}' \
-      --preview-window 'up,60%,border-bottom,+{2}+3/3,~3'
-)
-[ -n "${selected[0]}" ] && vim "${selected[0]}" "+${selected[1]}"
+FZF_DEFAULT_COMMAND="$RG_PREFIX $(printf %q "$INITIAL_QUERY")" \
+fzf --ansi \
+    --disabled --query "$INITIAL_QUERY" \
+    --bind "change:reload:sleep 0.1; $RG_PREFIX {q} || true" \
+    --delimiter : \
+    --preview 'bat --color=always {1} --highlight-line {2}' \
+    --preview-window 'up,60%,border-bottom,+{2}+3/3,~3' \
+    --bind 'enter:become(vim {1} +{2})'
 ```
 
 ![image](https://user-images.githubusercontent.com/700826/113684212-f9ff0a00-96ff-11eb-8737-7bb571d320cc.png)
@@ -358,8 +361,6 @@ IFS=: read -ra selected < <(
 
 ### Switching to fzf-only search mode
 
-*(Requires fzf 0.27.1 or above)*
-
 In the previous example, we lost fuzzy matching capability as we completely
 delegated search functionality to Ripgrep. But we can dynamically switch to
 fzf-only search mode by *"unbinding"* `reload` action from `change` event.
@@ -375,19 +376,17 @@ fzf-only search mode by *"unbinding"* `reload` action from `change` event.
 # 3. Open the file in Vim
 RG_PREFIX="rg --column --line-number --no-heading --color=always --smart-case "
 INITIAL_QUERY="${*:-}"
-IFS=: read -ra selected < <(
-  FZF_DEFAULT_COMMAND="$RG_PREFIX $(printf %q "$INITIAL_QUERY")" \
-  fzf --ansi \
-      --color "hl:-1:underline,hl+:-1:underline:reverse" \
-      --disabled --query "$INITIAL_QUERY" \
-      --bind "change:reload:sleep 0.1; $RG_PREFIX {q} || true" \
-      --bind "alt-enter:unbind(change,alt-enter)+change-prompt(2. fzf> )+enable-search+clear-query" \
-      --prompt '1. ripgrep> ' \
-      --delimiter : \
-      --preview 'bat --color=always {1} --highlight-line {2}' \
-      --preview-window 'up,60%,border-bottom,+{2}+3/3,~3'
-)
-[ -n "${selected[0]}" ] && vim "${selected[0]}" "+${selected[1]}"
+FZF_DEFAULT_COMMAND="$RG_PREFIX $(printf %q "$INITIAL_QUERY")" \
+fzf --ansi \
+    --color "hl:-1:underline,hl+:-1:underline:reverse" \
+    --disabled --query "$INITIAL_QUERY" \
+    --bind "change:reload:sleep 0.1; $RG_PREFIX {q} || true" \
+    --bind "alt-enter:unbind(change,alt-enter)+change-prompt(2. fzf> )+enable-search+clear-query" \
+    --prompt '1. ripgrep> ' \
+    --delimiter : \
+    --preview 'bat --color=always {1} --highlight-line {2}' \
+    --preview-window 'up,60%,border-bottom,+{2}+3/3,~3' \
+    --bind 'enter:become(vim {1} +{2})'
 ```
 
 * Phase 1. Filtering with Ripgrep
@@ -408,10 +407,8 @@ IFS=: read -ra selected < <(
 
 ### Switching between Ripgrep mode and fzf mode
 
-*(Requires fzf 0.30.0 or above)*
-
-fzf 0.30.0 added `rebind` action so we can "rebind" the bindings that were
-previously "unbound" via `unbind`.
+[fzf 0.30.0][0.30.0] added `rebind` action so we can "rebind" the bindings
+that were previously "unbound" via `unbind`.
 
 This is an improved version of the previous example that allows us to switch
 between Ripgrep launcher mode and fzf-only filtering mode via CTRL-R and
@@ -421,25 +418,34 @@ CTRL-F.
 #!/usr/bin/env bash
 
 # Switch between Ripgrep launcher mode (CTRL-R) and fzf filtering mode (CTRL-F)
+rm -f /tmp/rg-fzf-{r,f}
 RG_PREFIX="rg --column --line-number --no-heading --color=always --smart-case "
 INITIAL_QUERY="${*:-}"
-IFS=: read -ra selected < <(
-  FZF_DEFAULT_COMMAND="$RG_PREFIX $(printf %q "$INITIAL_QUERY")" \
-  fzf --ansi \
-      --color "hl:-1:underline,hl+:-1:underline:reverse" \
-      --disabled --query "$INITIAL_QUERY" \
-      --bind "change:reload:sleep 0.1; $RG_PREFIX {q} || true" \
-      --bind "ctrl-f:unbind(change,ctrl-f)+change-prompt(2. fzf> )+enable-search+clear-query+rebind(ctrl-r)" \
-      --bind "ctrl-r:unbind(ctrl-r)+change-prompt(1. ripgrep> )+disable-search+reload($RG_PREFIX {q} || true)+rebind(change,ctrl-f)" \
-      --prompt '1. Ripgrep> ' \
-      --delimiter : \
-      --header '╱ CTRL-R (Ripgrep mode) ╱ CTRL-F (fzf mode) ╱' \
-      --preview 'bat --color=always {1} --highlight-line {2}' \
-      --preview-window 'up,60%,border-bottom,+{2}+3/3,~3'
-)
-[ -n "${selected[0]}" ] && vim "${selected[0]}" "+${selected[1]}"
+FZF_DEFAULT_COMMAND="$RG_PREFIX $(printf %q "$INITIAL_QUERY")" \
+fzf --ansi \
+    --color "hl:-1:underline,hl+:-1:underline:reverse" \
+    --disabled --query "$INITIAL_QUERY" \
+    --bind "change:reload:sleep 0.1; $RG_PREFIX {q} || true" \
+    --bind "ctrl-f:unbind(change,ctrl-f)+change-prompt(2. fzf> )+enable-search+rebind(ctrl-r)+transform-query(echo {q} > /tmp/rg-fzf-r; cat /tmp/rg-fzf-f)" \
+    --bind "ctrl-r:unbind(ctrl-r)+change-prompt(1. ripgrep> )+disable-search+reload($RG_PREFIX {q} || true)+rebind(change,ctrl-f)+transform-query(echo {q} > /tmp/rg-fzf-f; cat /tmp/rg-fzf-r)" \
+    --bind "start:unbind(ctrl-r)" \
+    --prompt '1. ripgrep> ' \
+    --delimiter : \
+    --header '╱ CTRL-R (ripgrep mode) ╱ CTRL-F (fzf mode) ╱' \
+    --preview 'bat --color=always {1} --highlight-line {2}' \
+    --preview-window 'up,60%,border-bottom,+{2}+3/3,~3' \
+    --bind 'enter:become(vim {1} +{2})'
 ```
 
+- To restore the query string when switching between modes, we store the
+  current query in `/tmp/rg-fzf-{r,f}` files and restore the query using
+  `transform-query` action which was added in [fzf 0.36.0][0.36.0].
+- Also note that we unbind `ctrl-r` binding on `start` event which is
+  triggered once when fzf starts.
+
+[0.30.0]: https://github.com/junegunn/fzf/blob/master/CHANGELOG.md#0300
+[0.36.0]: https://github.com/junegunn/fzf/blob/master/CHANGELOG.md#0360
+
 Log tailing
 -----------
 

CHANGELOG.md

@@ -1,6 +1,28 @@
 CHANGELOG
 =========
 
+0.38.0
+------
+- New actions
+    - `become(...)` - Replace the current fzf process with the specified
+      command using `execve(2)` system call.
+      See https://github.com/junegunn/fzf#turning-into-a-different-process for
+      more information.
+      ```sh
+      # Open selected files in Vim
+      fzf --multi --bind 'enter:become(vim {+})'
+
+      # Open the file in Vim and go to the line
+      git grep --line-number . |
+          fzf --delimiter : --nth 3.. --bind 'enter:become(vim {1} +{2})'
+      ```
+        - This action is not supported on Windows
+    - `show-preview`
+    - `hide-preview`
+- Bug fixes
+    - `--preview-window 0,hidden` should not execute the preview command until
+      `toggle-preview` action is triggered
+
 0.37.0
 ------
 - Added a way to customize the separator of inline info

README.md

@@ -54,6 +54,7 @@ Table of Contents
 * [Advanced topics](#advanced-topics)
     * [Performance](#performance)
     * [Executing external programs](#executing-external-programs)
+    * [Turning into a different process](#turning-into-a-different-process)
     * [Reloading the candidate list](#reloading-the-candidate-list)
         * [1. Update the list of processes by pressing CTRL-R](#1-update-the-list-of-processes-by-pressing-ctrl-r)
         * [2. Switch between sources by pressing CTRL-D or CTRL-F](#2-switch-between-sources-by-pressing-ctrl-d-or-ctrl-f)
@@ -136,15 +137,17 @@ git clone --depth 1 https://github.com/junegunn/fzf.git ~/.fzf
 ### Windows
 
 Pre-built binaries for Windows can be downloaded [here][bin]. fzf is also
-available via [Chocolatey][choco] and [Scoop][scoop]:
+available via [Chocolatey][choco], [Scoop][scoop], and [Winget][winget]:
 
-| Package manager | Command             |
-| ---             | ---                 |
-| Chocolatey      | `choco install fzf` |
-| Scoop           | `scoop install fzf` |
+| Package manager | Command              |
+| ---             | ---                  |
+| Chocolatey      | `choco install fzf`  |
+| Scoop           | `scoop install fzf`  |
+| Winget          | `winget install fzf` |
 
 [choco]: https://chocolatey.org/packages/fzf
 [scoop]: https://github.com/ScoopInstaller/Main/blob/master/bucket/fzf.json
+[winget]: https://github.com/microsoft/winget-pkgs/tree/master/manifests/j/junegunn/fzf
 
 Known issues and limitations on Windows can be found on [the wiki
 page][windows-wiki].
@@ -202,6 +205,22 @@ files excluding hidden ones. (You can override the default command with
 vim $(fzf)
 ```
 
+> *:bulb: A more robust solution would be to use `xargs` but we've presented
+> the above as it's easier to grasp*
+> ```sh
+> fzf --print0 | xargs -0 -o vim
+> ```
+
+>
+> *:bulb: fzf also has the ability to turn itself into a different process.*
+>
+> ```sh
+> fzf --bind 'enter:become(vim {})'
+> ```
+>
+> *See [Turning into a different process](#turning-into-a-different-process)
+> for more information.*
+
 ### Using the finder
 
 - `CTRL-K` / `CTRL-J` (or `CTRL-P` / `CTRL-N`) to move cursor up and down
@@ -560,6 +579,47 @@ fzf --bind 'f1:execute(less -f {}),ctrl-y:execute-silent(echo {} | pbcopy)+abort
 
 See *KEY BINDINGS* section of the man page for details.
 
+### Turning into a different process
+
+`become(...)` is similar to `execute(...)`/`execute-silent(...)` described
+above, but instead of executing the command and coming back to fzf on
+complete, it turns fzf into a new process for the command.
+
+```sh
+fzf --bind 'enter:become(vim {})'
+```
+
+Compared to the seemingly equivalent command substitution `vim "$(fzf)"`, this
+approach has several advantages:
+
+* Vim will not open an empty file when you terminate fzf with
+  <kbd>CTRL-C</kbd>
+* Vim will not open an empty file when you press <kbd>ENTER</kbd> on an empty
+  result
+* Can handle multiple selections even when they have whitespaces
+  ```sh
+  fzf --multi --bind 'enter:become(vim {+})'
+  ```
+
+To be fair, running `fzf --print0 | xargs -0 -o vim` instead of `vim "$(fzf)"`
+resolves all of the issues mentioned. Nonetheless, `become(...)` still offers
+additional benefits in different scenarios.
+
+* You can set up multiple bindings to handle the result in different ways
+  without any wrapping script
+  ```sh
+  fzf --bind 'enter:become(vim {}),ctrl-e:become(emacs {})'
+  ```
+  * Previously, you would have to use `--expect=ctrl-e` and check the first
+    line of the output of fzf
+* You can easily build the subsequent command using the field index
+  expressions of fzf
+  ```sh
+  # Open the file in Vim and go to the line
+  git grep --line-number . |
+      fzf --delimiter : --nth 3.. --bind 'enter:become(vim {1} +{2})'
+  ```
+
 ### Reloading the candidate list
 
 By binding `reload` action to a key or an event, you can make fzf dynamically

bin/fzf-tmux

@@ -179,9 +179,10 @@ trap 'cleanup' EXIT
 
 envs="export TERM=$TERM "
 if [[ "$opt" =~ "-E" ]]; then
-  FZF_DEFAULT_OPTS="--margin 0,1 $FZF_DEFAULT_OPTS"
   tmux_version=$(tmux -V)
-  if [[ ! $tmux_version =~ 3\.2 ]]; then
+  if [[ $tmux_version =~ ^tmux\ 3\.2[a-z]?$ ]]; then
+    FZF_DEFAULT_OPTS="--margin 0,1 $FZF_DEFAULT_OPTS"
+  else
     FZF_DEFAULT_OPTS="--border $FZF_DEFAULT_OPTS"
     opt="-B $opt"
   fi

install

@@ -2,7 +2,7 @@
 
 set -u
 
-version=0.37.0
+version=0.38.0
 auto_completion=
 key_bindings=
 update_config=2

install.ps1

@@ -1,4 +1,4 @@
-$version="0.37.0"
+$version="0.38.0"
 
 $fzf_base=Split-Path -Parent $MyInvocation.MyCommand.Definition
 

main.go

@@ -5,7 +5,7 @@ import (
 	"github.com/junegunn/fzf/src/protector"
 )
 
-var version string = "0.37"
+var version string = "0.38"
 var revision string = "devel"
 
 func main() {

man/man1/fzf-tmux.1

@@ -21,7 +21,7 @@ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
 ..
-.TH fzf-tmux 1 "Jan 2023" "fzf 0.37.0" "fzf-tmux - open fzf in tmux split pane"
+.TH fzf-tmux 1 "Feb 2023" "fzf 0.38.0" "fzf-tmux - open fzf in tmux split pane"
 
 .SH NAME
 fzf-tmux - open fzf in tmux split pane

man/man1/fzf.1

@@ -21,7 +21,7 @@ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
 ..
-.TH fzf 1 "Jan 2023" "fzf 0.37.0" "fzf - a command-line fuzzy finder"
+.TH fzf 1 "Feb 2023" "fzf 0.38.0" "fzf - a command-line fuzzy finder"
 
 .SH NAME
 fzf - a command-line fuzzy finder
@@ -999,6 +999,7 @@ A key or an event can be bound to one or more of the following actions.
     \fBbackward-delete-char/eof\fR     (same as \fBbackward-delete-char\fR except aborts fzf if query is empty)
     \fBbackward-kill-word\fR           \fIalt-bs\fR
     \fBbackward-word\fR                \fIalt-b   shift-left\fR
+    \fBbecome(...)\fR                  (replace fzf process with the specified command; see below for the details)
     \fBbeginning-of-line\fR            \fIctrl-a  home\fR
     \fBcancel\fR                       (clear query string if not empty, abort fzf otherwise)
     \fBchange-border-label(...)\fR     (change \fB--border-label\fR to the given string)
@@ -1036,6 +1037,7 @@ A key or an event can be bound to one or more of the following actions.
     \fBpage-up\fR                      \fIpgup\fR
     \fBhalf-page-down\fR
     \fBhalf-page-up\fR
+    \fBhide-preview\fR
     \fBpos(...)\fR                     (move cursor to the numeric position; negative number to count from the end)
     \fBprev-history\fR                 (\fIctrl-p\fR on \fB--history\fR)
     \fBprev-selected\fR                (move to the previous selected item)
@@ -1058,6 +1060,7 @@ A key or an event can be bound to one or more of the following actions.
     \fBreplace-query\fR                (replace query string with the current selection)
     \fBselect\fR
     \fBselect-all\fR                   (select all matches)
+    \fBshow-preview\fR
     \fBtoggle\fR                       (\fIright-click\fR)
     \fBtoggle-all\fR                   (toggle all matches)
     \fBtoggle+down\fR                  \fIctrl-i  (tab)\fR
@@ -1141,6 +1144,14 @@ On *nix systems, fzf runs the command with \fB$SHELL -c\fR if \fBSHELL\fR is
 set, otherwise with \fBsh -c\fR, so in this case make sure that the command is
 POSIX-compliant.
 
+\fBbecome(...)\fR action is similar to \fBexecute(...)\fR, but it replaces the
+current fzf process with the specifed command using \fBexecve(2)\fR system
+call.
+
+    \fBfzf --bind "enter:become(vim {})"\fR
+
+\fBbecome(...)\fR is not supported on Windows.
+
 .SS RELOAD INPUT
 
 \fBreload(...)\fR action is used to dynamically update the input list

plugin/fzf.vim

@@ -512,9 +512,7 @@ try
     let optstr .= ' --height='.height
   endif
   " Respect --border option given in 'options'
-  if stridx(optstr, '--border') < 0 && stridx(optstr, '--no-border') < 0
-    let optstr .= s:border_opt(get(dict, 'window', 0))
-  endif
+  let optstr = join([s:border_opt(get(dict, 'window', 0)), optstr])
   let prev_default_command = $FZF_DEFAULT_COMMAND
   if len(source_command)
     let $FZF_DEFAULT_COMMAND = source_command
@@ -741,7 +739,7 @@ function! s:calc_size(max, val, dict)
     return size
   endif
   let margin = match(opts, '--inline-info\|--info[^-]\{-}inline') > match(opts, '--no-inline-info\|--info[^-]\{-}\(default\|hidden\)') ? 1 : 2
-  let margin += stridx(opts, '--border') > stridx(opts, '--no-border') ? 2 : 0
+  let margin += match(opts, '--border\([^-]\|$\)') > match(opts, '--no-border\([^-]\|$\)') ? 2 : 0
   if stridx(opts, '--header') > stridx(opts, '--no-header')
     let margin += len(split(opts, "\n"))
   endif

shell/completion.bash

@@ -373,7 +373,7 @@ _fzf_setup_completion() {
 }
 
 # Environment variables / Aliases / Hosts / Process
-_fzf_setup_completion 'var'   export unset
+_fzf_setup_completion 'var'   export unset printenv
 _fzf_setup_completion 'alias' unalias
 _fzf_setup_completion 'host'  ssh telnet
 _fzf_setup_completion 'proc'  kill

src/options.go

@@ -10,6 +10,7 @@ import (
 
 	"github.com/junegunn/fzf/src/algo"
 	"github.com/junegunn/fzf/src/tui"
+	"github.com/junegunn/fzf/src/util"
 
 	"github.com/mattn/go-runewidth"
 	"github.com/mattn/go-shellwords"
@@ -921,7 +922,7 @@ const (
 
 func init() {
 	executeRegexp = regexp.MustCompile(
-		`(?si)[:+](execute(?:-multi|-silent)?|reload(?:-sync)?|preview|(?:change|transform)-(?:query|prompt|border-label|preview-label)|change-preview-window|change-preview|(?:re|un)bind|pos|put)`)
+		`(?si)[:+](become|execute(?:-multi|-silent)?|reload(?:-sync)?|preview|(?:change|transform)-(?:query|prompt|border-label|preview-label)|change-preview-window|change-preview|(?:re|un)bind|pos|put)`)
 	splitRegexp = regexp.MustCompile("[,:]+")
 	actionNameRegexp = regexp.MustCompile("(?i)^[a-z-]+")
 }
@@ -1111,6 +1112,10 @@ func parseActionList(masked string, original string, prevActions []*action, putA
 			appendAction(actPrevSelected)
 		case "next-selected":
 			appendAction(actNextSelected)
+		case "show-preview":
+			appendAction(actShowPreview)
+		case "hide-preview":
+			appendAction(actHidePreview)
 		case "toggle-preview":
 			appendAction(actTogglePreview)
 		case "toggle-preview-wrap":
@@ -1167,6 +1172,10 @@ func parseActionList(masked string, original string, prevActions []*action, putA
 					actions = append(actions, &action{t: t, a: actionArg})
 				}
 				switch t {
+				case actBecome:
+					if util.IsWindows() {
+						exit("become action is not supported on Windows")
+					}
 				case actUnbind, actRebind:
 					parseKeyChordsImpl(actionArg, spec[0:offset]+" target required", exit)
 				case actChangePreviewWindow:
@@ -1219,6 +1228,8 @@ func isExecuteAction(str string) actionType {
 
 	prefix := actionNameRegexp.FindString(str)
 	switch prefix {
+	case "become":
+		return actBecome
 	case "reload":
 		return actReload
 	case "reload-sync":

src/terminal.go

@@ -6,6 +6,7 @@ import (
 	"io/ioutil"
 	"math"
 	"os"
+	"os/exec"
 	"os/signal"
 	"regexp"
 	"sort"
@@ -104,7 +105,6 @@ type previewer struct {
 	version    int64
 	lines      []string
 	offset     int
-	enabled    bool
 	scrollable bool
 	final      bool
 	following  resumableState
@@ -350,6 +350,8 @@ const (
 	actRefreshPreview
 	actReplaceQuery
 	actToggleSort
+	actShowPreview
+	actHidePreview
 	actTogglePreview
 	actTogglePreviewWrap
 	actTransformBorderLabel
@@ -386,6 +388,7 @@ const (
 	actDeselect
 	actUnbind
 	actRebind
+	actBecome
 )
 
 type placeholderFlags struct {
@@ -643,7 +646,7 @@ func NewTerminal(opts *Options, eventBox *util.EventBox) *Terminal {
 		reqBox:             util.NewEventBox(),
 		initialPreviewOpts: opts.Preview,
 		previewOpts:        opts.Preview,
-		previewer:          previewer{0, []string{}, 0, len(opts.Preview.command) > 0, false, true, disabledState, "", []bool{}},
+		previewer:          previewer{0, []string{}, 0, false, true, disabledState, "", []bool{}},
 		previewed:          previewed{0, 0, 0, false},
 		previewBox:         previewBox,
 		eventBox:           eventBox,
@@ -1032,7 +1035,7 @@ func (t *Terminal) adjustMarginAndPadding() (int, int, [4]int, [4]int) {
 	if t.noInfoLine() {
 		minAreaHeight -= 1
 	}
-	if t.mayNeedPreviewWindow() {
+	if t.needPreviewWindow() {
 		minPreviewHeight := 1 + borderLines(t.previewOpts.border)
 		minPreviewWidth := 5
 		switch t.previewOpts.position {
@@ -1115,7 +1118,7 @@ func (t *Terminal) resizeWindows(forcePreview bool) {
 
 	// Set up preview window
 	noBorder := tui.MakeBorderStyle(tui.BorderNone, t.unicode)
-	if t.mayNeedPreviewWindow() {
+	if forcePreview || t.needPreviewWindow() {
 		var resizePreviewWindows func(previewOpts *previewOpts)
 		resizePreviewWindows = func(previewOpts *previewOpts) {
 			t.activePreviewOpts = previewOpts
@@ -1244,6 +1247,8 @@ func (t *Terminal) resizeWindows(forcePreview bool) {
 			}
 		}
 		resizePreviewWindows(&t.previewOpts)
+	} else {
+		t.activePreviewOpts = &t.previewOpts
 	}
 
 	// Without preview window
@@ -2234,7 +2239,7 @@ func (t *Terminal) redraw() {
 
 func (t *Terminal) executeCommand(template string, forcePlus bool, background bool, captureFirstLine bool) string {
 	line := ""
-	valid, list := t.buildPlusList(template, forcePlus, false)
+	valid, list := t.buildPlusList(template, forcePlus)
 	// captureFirstLine is used for transform-{prompt,query} and we don't want to
 	// return an empty string in those cases
 	if !valid && !captureFirstLine {
@@ -2273,13 +2278,13 @@ func (t *Terminal) hasPreviewer() bool {
 	return t.previewBox != nil
 }
 
-func (t *Terminal) mayNeedPreviewWindow() bool {
-	return t.hasPreviewer() && t.previewer.enabled && t.previewOpts.Visible()
+func (t *Terminal) needPreviewWindow() bool {
+	return t.hasPreviewer() && len(t.previewOpts.command) > 0 && t.previewOpts.Visible()
 }
 
 // Check if previewer is currently in action (invisible previewer with size 0 or visible previewer)
-func (t *Terminal) isPreviewEnabled() bool {
-	return t.hasPreviewer() && t.previewer.enabled && (!t.previewOpts.Visible() || t.pwindow != nil)
+func (t *Terminal) canPreview() bool {
+	return t.hasPreviewer() && (!t.previewOpts.Visible() && !t.previewOpts.hidden || t.hasPreviewWindow())
 }
 
 func (t *Terminal) hasPreviewWindow() bool {
@@ -2294,10 +2299,10 @@ func (t *Terminal) currentItem() *Item {
 	return nil
 }
 
-func (t *Terminal) buildPlusList(template string, forcePlus bool, forceEvaluation bool) (bool, []*Item) {
+func (t *Terminal) buildPlusList(template string, forcePlus bool) (bool, []*Item) {
 	current := t.currentItem()
 	slot, plus, query := hasPreviewFlags(template)
-	if !forceEvaluation && !(!slot || query || (forcePlus || plus) && len(t.selected) > 0) {
+	if !(!slot || query || (forcePlus || plus) && len(t.selected) > 0) {
 		return current != nil, []*Item{current, current}
 	}
 
@@ -2387,7 +2392,7 @@ func (t *Terminal) Loop() {
 		pad := fitpad.pad
 		t.tui.Resize(func(termHeight int) int {
 			contentHeight := fit + t.extraLines()
-			if t.mayNeedPreviewWindow() {
+			if t.needPreviewWindow() {
 				if t.previewOpts.aboveOrBelow() {
 					if t.previewOpts.size.percent {
 						newContentHeight := int(float64(contentHeight) * 100. / (100. - t.previewOpts.size.size))
@@ -2621,8 +2626,8 @@ func (t *Terminal) Loop() {
 	}
 
 	refreshPreview := func(command string) {
-		if len(command) > 0 && t.isPreviewEnabled() {
-			_, list := t.buildPlusList(command, false, false)
+		if len(command) > 0 && t.canPreview() {
+			_, list := t.buildPlusList(command, false)
 			t.cancelPreview()
 			t.previewBox.Set(reqPreviewEnqueue, previewRequest{command, t.pwindow, t.evaluateScrollOffset(), list})
 		}
@@ -2696,7 +2701,7 @@ func (t *Terminal) Loop() {
 					case reqFullRedraw:
 						wasHidden := t.pwindow == nil
 						t.redraw()
-						if wasHidden && t.pwindow != nil {
+						if wasHidden && t.hasPreviewWindow() {
 							refreshPreview(t.previewOpts.command)
 						}
 					case reqClose:
@@ -2857,6 +2862,24 @@ func (t *Terminal) Loop() {
 		doAction = func(a *action) bool {
 			switch a.t {
 			case actIgnore:
+			case actBecome:
+				valid, list := t.buildPlusList(a.a, false)
+				if valid {
+					command := t.replacePlaceholder(a.a, false, string(t.input), list)
+					shell := os.Getenv("SHELL")
+					if len(shell) == 0 {
+						shell = "sh"
+					}
+					shellPath, err := exec.LookPath(shell)
+					if err == nil {
+						t.tui.Close()
+						if t.history != nil {
+							t.history.append(string(t.input))
+						}
+						util.SetStdin(tui.TtyIn())
+						syscall.Exec(shellPath, []string{shell, "-c", command}, os.Environ())
+					}
+				}
 			case actExecute, actExecuteSilent:
 				t.executeCommand(a.a, false, a.t == actExecuteSilent, false)
 			case actExecuteMulti:
@@ -2864,16 +2887,21 @@ func (t *Terminal) Loop() {
 			case actInvalid:
 				t.mutex.Unlock()
 				return false
-			case actTogglePreview:
-				if t.hasPreviewer() {
-					if t.activePreviewOpts != nil {
-						t.activePreviewOpts.Toggle()
-					} else if !t.previewOpts.Visible() {
-						t.previewer.enabled = !t.previewer.enabled
-					}
+			case actTogglePreview, actShowPreview, actHidePreview:
+				var act bool
+				switch a.t {
+				case actShowPreview:
+					act = !t.hasPreviewWindow() && len(t.previewOpts.command) > 0
+				case actHidePreview:
+					act = t.hasPreviewWindow()
+				case actTogglePreview:
+					act = t.hasPreviewWindow() || len(t.previewOpts.command) > 0
+				}
+				if act {
+					t.activePreviewOpts.Toggle()
 					updatePreviewWindow(false)
-					if t.isPreviewEnabled() {
-						valid, list := t.buildPlusList(t.previewOpts.command, false, false)
+					if t.canPreview() {
+						valid, list := t.buildPlusList(t.previewOpts.command, false)
 						if valid {
 							t.cancelPreview()
 							t.previewBox.Set(reqPreviewEnqueue,
@@ -2968,7 +2996,6 @@ func (t *Terminal) Loop() {
 				t.prompt, t.promptLen = t.parsePrompt(a.a)
 				req(reqPrompt)
 			case actPreview:
-				t.previewer.enabled = true
 				updatePreviewWindow(true)
 				refreshPreview(a.a)
 			case actRefreshPreview:
@@ -3353,7 +3380,7 @@ func (t *Terminal) Loop() {
 			case actReload, actReloadSync:
 				t.failed = nil
 
-				valid, list := t.buildPlusList(a.a, false, false)
+				valid, list := t.buildPlusList(a.a, false)
 				if !valid {
 					// We run the command even when there's no match
 					// 1. If the template doesn't have any slots
@@ -3381,9 +3408,8 @@ func (t *Terminal) Loop() {
 				}
 			case actChangePreview:
 				if t.previewOpts.command != a.a {
-					t.previewer.enabled = len(a.a) > 0
-					updatePreviewWindow(false)
 					t.previewOpts.command = a.a
+					updatePreviewWindow(false)
 					refreshPreview(t.previewOpts.command)
 				}
 			case actChangePreviewWindow:
@@ -3403,7 +3429,7 @@ func (t *Terminal) Loop() {
 				if !currentPreviewOpts.sameLayout(t.previewOpts) {
 					wasHidden := t.pwindow == nil
 					updatePreviewWindow(false)
-					if wasHidden && t.pwindow != nil {
+					if wasHidden && t.hasPreviewWindow() {
 						refreshPreview(t.previewOpts.command)
 					} else {
 						req(reqPreviewRefresh)
@@ -3480,12 +3506,10 @@ func (t *Terminal) Loop() {
 			req(reqList)
 		}
 
-		if queryChanged {
-			if t.isPreviewEnabled() {
-				_, _, q := hasPreviewFlags(t.previewOpts.command)
-				if q {
-					t.version++
-				}
+		if queryChanged && t.canPreview() && len(t.previewOpts.command) > 0 {
+			_, _, q := hasPreviewFlags(t.previewOpts.command)
+			if q {
+				t.version++
 			}
 		}
 

src/util/util_unix.go

@@ -6,6 +6,8 @@ import (
 	"os"
 	"os/exec"
 	"syscall"
+
+	"golang.org/x/sys/unix"
 )
 
 // ExecCommand executes the given command with $SHELL
@@ -45,3 +47,7 @@ func SetNonblock(file *os.File, nonblock bool) {
 func Read(fd int, b []byte) (int, error) {
 	return syscall.Read(int(fd), b)
 }
+
+func SetStdin(file *os.File) {
+	unix.Dup2(int(file.Fd()), 0)
+}

src/util/util_windows.go

@@ -81,3 +81,7 @@ func SetNonblock(file *os.File, nonblock bool) {
 func Read(fd int, b []byte) (int, error) {
 	return syscall.Read(syscall.Handle(fd), b)
 }
+
+func SetStdin(file *os.File) {
+	// No-op
+}

test/test_go.rb

@@ -180,7 +180,7 @@ class TestBase < Minitest::Test
   end
 
   def writelines(path, lines)
-    File.unlink(path) while File.exist?(path)
+    FileUtils.rm_f(path) while File.exist?(path)
     File.open(path, 'w') { |f| f.puts lines }
   end
 
@@ -188,7 +188,7 @@ class TestBase < Minitest::Test
     wait { assert_path_exists tempname }
     File.read(tempname)
   ensure
-    File.unlink(tempname) while File.exist?(tempname)
+    FileUtils.rm_f(tempname) while File.exist?(tempname)
     @temp_suffix += 1
     tmux.prepare
   end
@@ -905,11 +905,7 @@ class TestGoFZF < TestBase
     history_file = '/tmp/fzf-test-history'
 
     # History with limited number of entries
-    begin
-      File.unlink(history_file)
-    rescue StandardError
-      nil
-    end
+    FileUtils.rm_f(history_file)
     opts = "--history=#{history_file} --history-size=4"
     input = %w[00 11 22 33 44]
     input.each do |keys|
@@ -955,7 +951,7 @@ class TestGoFZF < TestBase
     tmux.until { |lines| assert_equal '> 33', lines[-1] }
     tmux.send_keys :Enter
   ensure
-    File.unlink(history_file)
+    FileUtils.rm_f(history_file)
   end
 
   def test_execute
@@ -984,11 +980,7 @@ class TestGoFZF < TestBase
       ], File.readlines(output, chomp: true)
     end
   ensure
-    begin
-      File.unlink(output)
-    rescue StandardError
-      nil
-    end
+    FileUtils.rm_f(output)
   end
 
   def test_execute_multi
@@ -1013,20 +1005,12 @@ class TestGoFZF < TestBase
       ], File.readlines(output, chomp: true)
     end
   ensure
-    begin
-      File.unlink(output)
-    rescue StandardError
-      nil
-    end
+    FileUtils.rm_f(output)
   end
 
   def test_execute_plus_flag
     output = tempname + '.tmp'
-    begin
-      File.unlink(output)
-    rescue StandardError
-      nil
-    end
+    FileUtils.rm_f(output)
     writelines(tempname, ['foo bar', '123 456'])
 
     tmux.send_keys "cat #{tempname} | #{FZF} --multi --bind 'x:execute-silent(echo {+}/{}/{+2}/{2} >> #{output})'", :Enter
@@ -1059,21 +1043,13 @@ class TestGoFZF < TestBase
       ], File.readlines(output, chomp: true)
     end
   rescue StandardError
-    begin
-      File.unlink(output)
-    rescue StandardError
-      nil
-    end
+    FileUtils.rm_f(output)
   end
 
   def test_execute_shell
     # Custom script to use as $SHELL
     output = tempname + '.out'
-    begin
-      File.unlink(output)
-    rescue StandardError
-      nil
-    end
+    FileUtils.rm_f(output)
     writelines(tempname,
                ['#!/usr/bin/env bash', "echo $1 / $2 > #{output}"])
     system("chmod +x #{tempname}")
@@ -1087,11 +1063,7 @@ class TestGoFZF < TestBase
       assert_equal ["-c / 'foo'bar"], File.readlines(output, chomp: true)
     end
   ensure
-    begin
-      File.unlink(output)
-    rescue StandardError
-      nil
-    end
+    FileUtils.rm_f(output)
   end
 
   def test_cycle
@@ -1485,6 +1457,83 @@ class TestGoFZF < TestBase
     tmux.until { |lines| assert_includes lines[1], ' {5-1  3 4} ' }
   end
 
+  def test_toggle_preview_without_default_preview_command
+    tmux.send_keys %(seq 100 | #{FZF} --bind 'space:preview(echo [{}]),enter:toggle-preview' --preview-window up,border-double), :Enter
+    tmux.until do |lines|
+      assert_equal 100, lines.match_count
+      refute_includes lines[1], '║ [1]'
+    end
+
+    # toggle-preview should do nothing
+    tmux.send_keys :Enter
+    tmux.until { |lines| refute_includes lines[1], '║ [1]' }
+    tmux.send_keys :Up
+    tmux.until do |lines|
+      refute_includes lines[1], '║ [1]'
+      refute_includes lines[1], '║ [2]'
+    end
+
+    tmux.send_keys :Up
+    tmux.until do |lines|
+      assert_includes lines, '> 3'
+      refute_includes lines[1], '║ [3]'
+    end
+
+    # One-off preview action
+    tmux.send_keys :Space
+    tmux.until { |lines| assert_includes lines[1], '║ [3]' }
+
+    # toggle-preview to hide it
+    tmux.send_keys :Enter
+    tmux.until { |lines| refute_includes lines[1], '║ [3]' }
+
+    # toggle-preview again does nothing
+    tmux.send_keys :Enter, :Up
+    tmux.until do |lines|
+      assert_includes lines, '> 4'
+      refute_includes lines[1], '║ [4]'
+    end
+  end
+
+  def test_show_and_hide_preview
+    tmux.send_keys %(seq 100 | #{FZF} --preview-window hidden,border-bold --preview 'echo [{}]' --bind 'a:show-preview,b:hide-preview'), :Enter
+
+    # Hidden by default
+    tmux.until do |lines|
+      assert_equal 100, lines.match_count
+      refute_includes lines[1], '┃ [1]'
+    end
+
+    # Show
+    tmux.send_keys :a
+    tmux.until { |lines| assert_includes lines[1], '┃ [1]' }
+
+    # Already shown
+    tmux.send_keys :a
+    tmux.send_keys :Up
+    tmux.until { |lines| assert_includes lines[1], '┃ [2]' }
+
+    # Hide
+    tmux.send_keys :b
+    tmux.send_keys :Up
+    tmux.until do |lines|
+      assert_includes lines, '> 3'
+      refute_includes lines[1], '┃ [3]'
+    end
+
+    # Already hidden
+    tmux.send_keys :b
+    tmux.send_keys :Up
+    tmux.until do |lines|
+      assert_includes lines, '> 4'
+      refute_includes lines[1], '┃ [4]'
+    end
+
+    # Show it again
+    tmux.send_keys :a
+    tmux.until { |lines| assert_includes lines[1], '┃ [4]' }
+  end
+
   def test_preview_hidden
     tmux.send_keys %(seq 1000 | #{FZF} --preview 'echo {{}-{}-$FZF_PREVIEW_LINES-$FZF_PREVIEW_COLUMNS}' --preview-window down:1:hidden --bind ?:toggle-preview), :Enter
     tmux.until { |lines| assert_equal '>', lines[-1] }
@@ -1497,11 +1546,7 @@ class TestGoFZF < TestBase
   end
 
   def test_preview_size_0
-    begin
-      File.unlink(tempname)
-    rescue StandardError
-      nil
-    end
+    FileUtils.rm_f(tempname)
     tmux.send_keys %(seq 100 | #{FZF} --reverse --preview 'echo {} >> #{tempname}; echo ' --preview-window 0 --bind space:toggle-preview), :Enter
     tmux.until do |lines|
       assert_equal 100, lines.item_count
@@ -1526,6 +1571,32 @@ class TestGoFZF < TestBase
     end
   end
 
+  def test_preview_size_0_hidden
+    FileUtils.rm_f(tempname)
+    tmux.send_keys %(seq 100 | #{FZF} --reverse --preview 'echo {} >> #{tempname}; echo ' --preview-window 0,hidden --bind space:toggle-preview), :Enter
+    tmux.until { |lines| assert_equal 100, lines.item_count }
+    tmux.send_keys :Down, :Down
+    tmux.until { |lines| assert_includes lines, '> 3' }
+    wait { refute_path_exists tempname }
+    tmux.send_keys :Space
+    wait do
+      assert_path_exists tempname
+      assert_equal %w[3], File.readlines(tempname, chomp: true)
+    end
+    tmux.send_keys :Down
+    wait do
+      assert_equal %w[3 4], File.readlines(tempname, chomp: true)
+    end
+    tmux.send_keys :Space, :Down
+    tmux.until { |lines| assert_includes lines, '> 5' }
+    tmux.send_keys :Down
+    tmux.until { |lines| assert_includes lines, '> 6' }
+    tmux.send_keys :Space
+    wait do
+      assert_equal %w[3 4 6], File.readlines(tempname, chomp: true)
+    end
+  end
+
   def test_preview_flags
     tmux.send_keys %(seq 10 | sed 's/^/:: /; s/$/  /' |
         #{FZF} --multi --preview 'echo {{2}/{s2}/{+2}/{+s2}/{q}/{n}/{+n}}'), :Enter
@@ -2087,11 +2158,7 @@ class TestGoFZF < TestBase
     wait { refute system("pgrep -f #{script}") }
   ensure
     system("pkill -9 -f #{script}")
-    begin
-      File.unlink(script)
-    rescue StandardError
-      nil
-    end
+    FileUtils.rm_f(script)
   end
 
   def test_kill_default_command_on_accept
@@ -2109,11 +2176,7 @@ class TestGoFZF < TestBase
     wait { refute system("pgrep -f #{script}") }
   ensure
     system("pkill -9 -f #{script}")
-    begin
-      File.unlink(script)
-    rescue StandardError
-      nil
-    end
+    FileUtils.rm_f(script)
   end
 
   def test_kill_reload_command_on_abort
@@ -2134,11 +2197,7 @@ class TestGoFZF < TestBase
     wait { refute system("pgrep -f #{script}") }
   ensure
     system("pkill -9 -f #{script}")
-    begin
-      File.unlink(script)
-    rescue StandardError
-      nil
-    end
+    FileUtils.rm_f(script)
   end
 
   def test_kill_reload_command_on_accept
@@ -2158,11 +2217,7 @@ class TestGoFZF < TestBase
     wait { refute system("pgrep -f #{script}") }
   ensure
     system("pkill -9 -f #{script}")
-    begin
-      File.unlink(script)
-    rescue StandardError
-      nil
-    end
+    FileUtils.rm_f(script)
   end
 
   def test_preview_header
@@ -2588,6 +2643,19 @@ class TestGoFZF < TestBase
     tmux.send_keys :Space
     tmux.until { |lines| assert_includes lines, '/1/1/' }
   end
+
+  def test_become
+    tmux.send_keys "seq 100 | #{FZF} --bind 'enter:become:seq {} | #{FZF}'", :Enter
+    tmux.until { |lines| assert_equal 100, lines.item_count }
+    tmux.send_keys 999
+    tmux.until { |lines| assert_equal 0, lines.match_count }
+    tmux.send_keys :Enter
+    tmux.until { |lines| assert_equal 0, lines.match_count }
+    tmux.send_keys :BSpace
+    tmux.until { |lines| assert_equal 1, lines.match_count }
+    tmux.send_keys :Enter
+    tmux.until { |lines| assert_equal 99, lines.item_count }
+  end
 end
 
 module TestShell