first-avail-command

first-avail-command

first-avail-command is a command wrapper designed to be put in configuration files:

• where a command is accepted
• and there are several alternatives for the same task
• but it's not known which alternative is installed

Synopsis

first-avail-command ALTERNATIVE1 ALTERNATIVE2 [...] -- ARGS FOR COMMAND

In a config file, it should typically be called like this:

first-avail-command ALTERNATIVE1 ALTERNATIVE2 ALTERNATIVE3 --

The external runner will pass its own args after the --. first-avail-command will choose the first installed alternative and feed it the external args passed after --.

Samples

~/.gitconfig

[pager]
    diff = first-avail-command delta batcat bat diff-so-fancy --

What are those commands?

• delta
• bat (or batcat on some systems)
• diff-so-fancy

Shell config: fzf

export FZF_DEFAULT_COMMAND="first-avail-command fd 'rg --files' find --"

This sample shows in addition how to pass some arguments that are specific to an alternative: here, rg must be passed --files, but not other alternatives.

What are those commands?

• fzf
• rg
• fd

Shell config: ls

alias ll="first-avail-command exa ls -- -l"

This sample shows in addition how to feed some extra arguments in config, which must be allowed by all alternatives: here, both ls and exa will receive -l, in addition of args passed to the ll alias.

What are those commands?

• exa