How to check if a shell command exists

Question

I'm now using

silent! let l:status = system(l:command . ' > /dev/null')

if match(l:status, '\cunknown') != -1 || match(l:status, '\cnot') != -1
    echo 'command not found'
    return 0`enter code here`
endif

i know it's not complete but is there any better way to check?

edit

i'm now using

silent! let l:status = system('which espeak')

if l:status !~ '\w\+'
    echo 'command not found'
    return 0
endif

edit

changed from which to command https://unix.stackexchange.com/questions/85249/why-not-use-which-what-to-use-then

Answer 1

Incidentally vim has a special function just for this: executable().

Answer 2

thanks for the comments above, i'm using this code right now:

silent! let l:status = system('command -v ' . l:cmd)

if l:status !~ '\w\+'
    echo 'command not found'
    return -1
endif