Question

Is have a keyword in bash? Or do bash completion scripts use a language that is not bash?

have gcc &&
_gcc()
{

It is common. See: grep "have .* &&" /etc/bash_completion.d/*

I could not find any information on the bash completion tutorials I’ve seen and I could not find any information in man bash. It’s also difficult to google “have”. Where do I find documentation on this?

I’m guessing it has to do with making sure that there gcc exists in the PATH?

edit: yes. /etc/bash_completion contains:

have()
{
    unset -v have
    # Completions for system administrator commands are installed as well in
    # case completion is attempted via `sudo command ...'.
    PATH=$PATH:/sbin:/usr/sbin:/usr/local/sbin type $1 &>/dev/null &&
    have="yes"
}

Answer 1

have and _have are just two functions defined in the base bash_completion file. Between the two, they form a wrapper around the built-in type command to determine if a particular command/program available.

# This function checks whether we have a given program on the system.
#
_have()
{
    # Completions for system administrator commands are installed as well in
    # case completion is attempted via `sudo command ...'.
    PATH=$PATH:/usr/sbin:/sbin:/usr/local/sbin type $1 &>/dev/null
}

# Backwards compatibility for compat completions that use have().
# @deprecated should no longer be used; generally not needed with dynamically
#             loaded completions, and _have is suitable for runtime use.
have()
{
    unset -v have
    _have $1 && have=yes
}