FZF_CTRL_T_OPTS evaluates IF statement with system default shell

[lukejanicke]

I switch between Zsh and Fish on Mac.

I have found that FZF evaluates IF statements with the system default shell and not the current shell, if it is different. I am using an IF statement to conditionally set eza or bat in FZF_CTRL_T_OPTS. As a result, I can only use FZF like this when my current and system default shell match. I would like to better understand why and maybe resolve this limitation. My knowledge of shells is limited but I have done extensive troubleshooting to get to this point of understanding the situation. Hope someone can help!

Here are my Zsh and Fish configurations:

# ZSH ~/.zshrc
# CONTROL + T to preview file content using bat or directory structure using eza
export FZF_CTRL_T_OPTS="
  --walker-skip .git,node_modules,target
  --preview 'if [ -d {} ]; then eza --tree --color=always {}; else bat -n --color=always {}; fi'
  --bind 'ctrl-/:change-preview-window(down|hidden|)'
  --color header:italic
  --header 'Use CONTROL + / to toggle preview window'"

# FISH ~/.config/fish/config.fish
# CONTROL + T to preview file content using bat or directory structure using eza
set -x FZF_CTRL_T_OPTS "
  --walker-skip .git,node_modules,target
  --preview 'if test -d {}; eza --tree --colour=always --icons=always {}; else; bat -n --color=always {}; end'
  --bind 'ctrl-/:change-preview-window(down|hidden|)'
  --color header:italic
  --header 'Use CONTROL + / to toggle preview window'"

When I am in Zsh, but the system default shell is Fish, the IF statement in the Zsh configuration causes an error that is reported as a Fish error. And vice versa. When I am in Fish, but the system default shell is Zsh, the IF statement in the Fish configuration causes an error that is reported as a Zsh error.

In this screenshot, I have just set the system default shell to fish with sudo dscl . -create /Users/$(whoami) UserShell /opt/homebrew/bin/fish and opened a new terminal. I then switch to zsh and press CONTROL + Y. Here, you can clearly see that fish is reporting an error but showing the IF string from my zsh configuration. This means the IF string is being evaluated with a fish shell (the current system default) even though I am now in zsh.

In this screenshot, I have just set the system default shell to zsh with sudo dscl . -create /Users/$(whoami) UserShell /bin/zsh and opened a new terminal. I then switch to fish and press CONTROL + Y. The error is reported as a zsh error, even though I am now in fish. With some messing around, I was able to confirm that zsh is indeed getting the IF string from my fish configuration.

Here is a screenshot where it works because I am in fish and the system default shell is also fish.

[LangLangBart]

I have found that FZF evaluates IF statements with the system default shell and not the current shell, if it is different.

Note

fzf runs the command with $SHELL -c if SHELL is set, otherwise with sh -c

Try assigning SHELL in your zsh or fish config file to see if it works for you.

fzf --bind 'start:become:echo zsh $ZSH_VERSION fish $FISH_VERSION bash $BASH_VERSION'
# zsh 5.9 fish bash

SHELL=$(which fish)

fzf --bind 'start:become:echo zsh $ZSH_VERSION fish $FISH_VERSION bash $BASH_VERSION'
# zsh fish 3.7.1 bash

Alternatively, you can pass the --with-shell=STR¹ flag to fzf.

fzf --with-shell="$(which zsh) -c" \
  --bind 'start:become:echo zsh $ZSH_VERSION fish $FISH_VERSION bash $BASH_VERSION'
# zsh 5.9 fish bash

fzf --with-shell="$(which fish) -c" \
  --bind 'start:become:echo zsh $ZSH_VERSION fish $FISH_VERSION bash $BASH_VERSION'
# zsh fish 3.7.1 bash

fzf --with-shell="$(which bash) -c" \
  --bind 'start:become:echo zsh $ZSH_VERSION fish $FISH_VERSION bash $BASH_VERSION'
# zsh fish bash 5.2.37(1)-release

Footnotes

1. fzf/CHANGELOG.md 0.51.0 ↩

[lukejanicke]

Thank you! That works! ❤️

# ~/.config/fish/config.fish

# Set SHELL for Fish sessions
set -x SHELL (which fish)

# ~/.zshrc

# Set SHELL for Zsh sessions
export SHELL=$(which zsh)

And I’ll keep the --with-shell approach up my sleeve too! Much appreciated!