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.