my scripts rely heavily on external programs and scripts. I need to be sure that a program I need to call exists. Manually, I'd check this using 'which' in the commandline.
Is there an equivalent to File.exists?
for things in $PATH
?
(yes I guess I could parse %x[which scriptINeedToRun]
but that's not super elegant.
Thanks! yannick
UPDATE: Here's the solution I retained:
def command?(command) system("which #{ command} > /dev/null 2>&1") end
True cross-platform solution, works properly on Windows:
# Cross-platform way of finding an executable in the $PATH. # # which('ruby') #=> /usr/bin/ruby def which(cmd) exts = ENV['PATHEXT'] ? ENV['PATHEXT'].split(';') : [''] ENV['PATH'].split(File::PATH_SEPARATOR).each do |path| exts.each do |ext| exe = File.join(path, "#{cmd}#{ext}") return exe if File.executable?(exe) && !File.directory?(exe) end end nil end
This doesn't use host OS sniffing, and respects $PATHEXT which lists valid file extensions for executables on Windows.
Shelling out to which
works on many systems but not all.
Use find_executable
method from mkmf
which is included to stdlib.
require 'mkmf' find_executable 'ruby' #=> "/Users/narkoz/.rvm/rubies/ruby-2.0.0-p0/bin/ruby" find_executable 'which-ruby' #=> nil
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