How to run a shell function with execute or become

[rbhanot4739]

Lets say we have a shell function defined which can be do different things depending on the arguments passed to it. How can run this function by binding a key with become or execute action ? Here is the example code

greet(){
echo "Hello $@"
}

ls | fzf --bind '<some-key>:become(greet {})

Unfortunately the above does not seem to work key press fails with command greet not found. I have also tried exporting the function but with no success.
One workaround is to simply run the command directly inside the become like become(echo "Hello " {} which works but then if I have logic that I want to reuse across multiple bindings, I would have to repeat the same code.

Another way is to put this function into its own script and then invoke that script, which works, but moving these functions into their own scripts can be painful and overkill if I am working on something more involved .

Am I missing something obvious here, I have searched through docs, example sections, advanced section but could not find anything.

[LangLangBart]

This will depend on your shell. If you are using bash, try it with export -f. As a good measure, assign the SHELL variable to your bash executable, Alternatively, there is also the --with-shell flag.

greet(){
echo "Hello $@"
}
export -f greet
ls | SHELL=$(which bash) fzf --bind '<some-key>:become(greet {})

---

I have also tried exporting the function but with no success.

If you are using zsh, there is no export -f. See this discussion for workarounds: #3993

---

The key lesson to take away is that fzf executes these functions in a child process like this:

Note

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

[rbhanot4739]

@LangLangBart Yes, I am using zsh. I had considered squishing the function into a single command string but that can become really hard to read and debug. For shorter and one liner functions this approach would work just fine however for longer and complicated functions its non-trivial and I think maybe .zshenv is the way but as you mentioned that has another side effect of very loose code locality !

Is it possible to run the zsh function inside a bash subshell when fzf executes it ? I tried running the following from zshell but it din't work

greet(){
echo "Hello $@"
}
export -f greet
ls | SHELL=$(which bash) fzf --bind '<some-key>:become(greet {})

[LangLangBart]

Within a zsh environment, you can't run export -f greet; it will throw an error.

In a bash environment, like in a script, it will work.

#!/usr/bin/env bash
greet(){
echo "Hello $@"
}
export -f greet
ls | SHELL=$(which bash) fzf --bind '<some-key>:become(greet {})

---

Alternatively, source the function from a specific file and then run it.

# file: ~/greet.zsh
greet(){
echo "Hello $@"
}

# command line
ls | fzf --bind '<some-key>:become(source ~/greet.zsh; greet {})

---

There is also autoload, but this would also require you to write the function in its own file

man zshmisc | less --pattern "AUTOLOADING FUNCTIONS"

This is just an example of using the is-at-least¹ function that comes with every zsh version. Use autoload to call it and test if your fzf version is at least 0.40.1. This is just a demo to illustrate the point.

• is-at-least check if a given command version meets the requirements

autoload -Uz is-at-least
is-at-least 0.40.1 $(fzf --version) && echo YES || echo NO 

There are several useful functions available with every zsh version. You can find them in the share/zsh/functions directory of your zsh distribution, along with many other completion functions. zsh even includes a tetris game, which might not be very helpful, but is amusing.

man zshcontrib | less --pattern tetris

echo "Play Tetris" | SHELL="$(which zsh)" fzf --bind 'enter:become:autoload -Uz tetriscurses; tetriscurses'

Footnotes

1. zsh/code Functions/Misc/is-at-least ↩

[rbhanot4739]

This seems to be the most convenient way if I put this inside a script like test.sh.

#!/usr/bin/env bash
greet(){
echo "Hello $@"
}
export -f greet
ls | SHELL=$(which bash) fzf --bind '<some-key>:become(greet {})

But it still does not work if I run this script like bash test.sh.

Even with autoloading the function fzf somehow fails to correctly load the function, here is the snippet from .zshrc

fpath=(~/zsh_functions $fpath);
autoload -U $fpath[1]/*(.:t)

Now if I open a new shell and run greet Foo I get Hello Foo, but if I do

❯ ls |SHELL="$(which zsh)" fzf --bind 'enter:become(greet)'
zsh:1: command not found: greet

Even with explicit autoloading it isn't working.

❯ ls |SHELL="$(which zsh)" fzf --bind 'enter:become:autoload -Uz greet; greet'
zsh:1: greet: function definition file not found

Here is the functions directory and file named greet inside it.

zsh_functions
└── greet

[LangLangBart]

But it still does not work if I run this script like bash test.sh.

Unable to reproduce the issue. Tried it with the following.

cat <<'EOF' >/tmp/test.sh
#!/usr/bin/env bash
greet(){
echo "Hello $@"
}
export -f greet
ls | SHELL=$(which bash) fzf --bind 'enter:become(greet {})'
EOF

bash /tmp/test.sh

Could you enable xtrace ?

bash -x /tmp/test.sh

---

Even with explicit autoloading it isn't working.

Did you restart your shell before running the command to ensure that the FPATH variable was properly exported? Check the output when printing the listed paths in fpath.

: | SHELL="$(which zsh)" fzf --bind 'start:become: echo "$FPATH"'

or try

fpath=(~/zsh_functions $fpath)
export FPATH=$FPATH

Testing it in a clean environment:

command env -i HOME=$HOME TERM=$TERM USER=$USER PATH=$PATH zsh -f
cd ~
mkdir zsh_functions

cat <<'EOF' > zsh_functions/greet
echo "Hello $@"
EOF

fpath=(~/zsh_functions $fpath)
export FPATH=$FPATH

ls | SHELL="$(which zsh)" fzf --bind 'enter:become:autoload -Uz greet; greet {}'
Hello ...

[rbhanot4739]

@LangLangBart I did some more testing with bash script method and noticed something really strange, the script works outside of tmux but not within tmux. Here is the example

❯ cat  /tmp/test.sh
#!/usr/bin/env bash
greet() {
  echo "Hello $@"
}
export -f greet
ls | SHELL=$(which bash) fzf --bind 'enter:become(greet {})'

❯ FZF_DEFAULT_OPTS=""
❯ bash /tmp/test.sh
Hello catpuccin.txt

Now if I add the --tmux option to default opts, it breaks

❯ cat /tmp/test.sh
#!/usr/bin/env bash
greet() {
  echo "Hello $@"
}
export -f greet
ls | SHELL=$(which bash) fzf --bind 'enter:become(greet {})'

❯ FZF_DEFAULT_OPTS="--tmux"
❯ bash /tmp/test.sh
/opt/homebrew/bin/bash: line 1: greet: command not found

Not sure what's going on here.

[LangLangBart]

the script works outside of tmux but not within tmux

See #4001 (comment)