Realtime scp output with ruby
I have had an annoying problem recently with a shell script where it would not show the output of an scp command in realtime. Initially I was fighting with different methods of capturing output in realtime from a ruby script.
The solution to this which I went for is using IO.popen
eg.
def stdout_redirect(command)
f = IO.popen(command)
while line = f.gets
puts line
end
f.close
endHowever, this was only part of the solution. It wasnt working so I even tried implementing a solution in python.
import subprocess
def myrun(cmd):
"""from http://blog.kagesenshi.org/2008/02/teeing-python-subprocesspopen-output.html
"""
print "Running " + cmd
p = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
stdout = []
while True:
line = p.stdout.readline()
stdout.append(line)
print line,
if line == '' and p.poll() != None:
break
return ''.join(stdout)
myrun('scp -r "remote_server:/directory/test_copy" ~/test_files/')To my surprise, all was quiet so had a check in the terminal and it would output fine. Hmmm.
file1.txt 100% 0 0.0KB/s 00:00
file2.txt 100% 0 0.0KB/s 00:00
file3.txt 100% 0 0.0KB/s 00:00
file4.txt 100% 0 0.0KB/s 00:00
file5.txt 100% 0 0.0KB/s 00:00
file6.txt 100% 0 0.0KB/s 00:00
After some time with mr google, I managed to track down the issue with scp itself. It runs the isatty() function to check and see if the command is being run in a shell. If it is not, then all is quiet! This means ruby, python et al do not get scp output.
The solution thanks to stack exchange was to send all output to a shell!
eg. scp -r "remote_server:/directory/test_copy" ~/test_files/ > /dev/tty
Hope this helps you if you are having a similar issue!