Determine if a function exists in bash

by

Like this: [[ $(type -t foo) == function ]] && echo "Foo exists"

The built-in type command will tell you whether something is a function, built-in function, external command, or just not defined.

Additional examples:

$ LC_ALL=C type foo
bash: type: foo: not found

$ LC_ALL=C type ls
ls is aliased to `ls --color=auto'

$ which type

$ LC_ALL=C type type
type is a shell builtin

$ LC_ALL=C type -t rvm
function

$ if [ -n "$(LC_ALL=C type -t rvm)" ] && [ "$(LC_ALL=C type -t rvm)" = function ]; then echo rvm is a function; else echo rvm is NOT a function; fi
rvm is a function

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