Hello,
While testing ruby to execute external commands, i’m having a strange
behavior with some commands.
To give an example, I have a simple script which is echoing an external
command result.
I observe different behavior
— 1st test : DIR command —
-code- (just a simple echo) :
IO.popen(“dir”) do |f|
while line = f.gets
puts line;
end
end
-result- same as a regular dir executed as a commandline in windows
console :
D:\test>d:\temp\ruby-1.9\bin\ruby.exe test_dir.rb
Le volume dans le lecteur D s’appelle DONNEES
Le numéro de série du volume est C083-B188
Répertoire de D:\test
21/08/2012 13:25 .
21/08/2012 13:25 …
21/08/2012 13:22 temp
21/08/2012 13:24 84 test_dir.rb
21/08/2012 13:25 95 test_ping.rb
2 fichier(s) 179 octets
3 Rép(s) 13 118 869 504 octets libres
OK it works !
— 2nd test : PING command —
When I try to echo a simple ping localhost with the same script :
-code-
IO.popen(“ping localhost”) do |f|
while line = f.gets
puts line;
end
end
-result- I have a different output with annoying added line feeds which
are not visible in a regular command line :
D:\test>d:\temp\ruby-1.9\bin\ruby.exe test_ping.rb
Envoi d’une requête ‘ping’ sur PC43343 [127.0.0.1] avec 32 octets de
données :
Réponse de 127.0.0.1 : octets=32 temps<1ms TTL=128
Réponse de 127.0.0.1 : octets=32 temps<1ms TTL=128
Réponse de 127.0.0.1 : octets=32 temps<1ms TTL=128
Réponse de 127.0.0.1 : octets=32 temps<1ms TTL=128
Statistiques Ping pour 127.0.0.1:
Paquets : envoyés = 4, reçus = 4, perdus = 0 (perte 0%),
Durée approximative des boucles en millisecondes :
Minimum = 0ms, Maximum = 0ms, Moyenne = 0ms
Whereas a regular command line is more compact :
D:\test>ping localhost
Envoi d’une requête ‘ping’ sur PC43343 [127.0.0.1] avec 32 octets de
données :
Réponse de 127.0.0.1 : octets=32 temps<1ms TTL=128
Réponse de 127.0.0.1 : octets=32 temps<1ms TTL=128
Réponse de 127.0.0.1 : octets=32 temps<1ms TTL=128
Réponse de 127.0.0.1 : octets=32 temps<1ms TTL=128
Statistiques Ping pour 127.0.0.1:
Paquets : envoyés = 4, reçus = 4, perdus = 0 (perte 0%),
Durée approximative des boucles en millisecondes :
Minimum = 0ms, Maximum = 0ms, Moyenne = 0ms
-analysis- :
I have indeed many successive “\n” linefeeds :
-code-
output = IO.popen(“ping localhost”).readlines()
print output
-result-
["\n", “\n”, “Envoi d’une requ\x88te ‘ping’ sur PC43343 [127.0.0.1]
avec 32 oct
ets de donn\x82es\xFF:\n”, “\n”, “\n”, “\n”, “R\x82ponse de
127.0.0.1\xFF: octet
s=32 temps<1ms TTL=128\n”, “\n”, “R\x82ponse de 127.0.0.1\xFF:
octets=32 temps<1
ms TTL=128\n”, “\n”, "R\x82ponse de 127.0.0.1\xFF: octets=32 temps<1ms
TTL=128\n
", “\n”, “R\x82ponse de 127.0.0.1\xFF: octets=32 temps<1ms TTL=128\n”,
“\n”, “\n
“, “\n”, “Statistiques Ping pour 127.0.0.1:\n”, “\n”, "
Paquets\xFF: envoy\x8
2s = 4, re\x87us = 4, perdus = 0 (perte 0%),\n”, “\n”, “Dur\x82e
approximative d
es boucles en millisecondes :\n”, “\n”, " Minimum = 0ms, Maximum =
0ms, Moyen
ne = 0ms\n”, “\n”]
-notes-
. i have the same behavior if i use puts or print to echo on stdout.
. i have the same behavior too if i use other apis like popen2 /
popen3 (i tried many things even trying to change encoding mode but with
no success)
. i’m using ruby 1.9 on window XP profesionnal french
If you have any idea to explain such a behavior and any suggested
solution, i would be grateful.
Note : as i’m evaluating ruby as a scripting tool to write some system
scripts which will manipulate lots of input / output of external
commands, I don’t want to manipulate full output or line by line to
delete \n which is not a clean solution in my opinion - so solution MUST
be simple and easy 
?
thx by advance