$stdin

Ruby
1

Hello,

first excuse me my bad english.

i have write a little send_mail script. now i pipe the messagetext from
another program, like cat /var/mailtext| send-mail.rb

the program source:

smtp_message = “”

temp = $stdin

temp.each do |f|
smtp_message += f
end

this is runing very well, but when no text is in the pipe, the program
is waiting for input.

my question is, how can i ask, if text in $stdin, without the program is
waitung for input.

ciao

Stefan

2

Stefan Gremm wrote:

Hello,

first excuse me my bad english.

i have write a little send_mail script. now i pipe the messagetext from
another program, like cat /var/mailtext| send-mail.rb

the program source:

smtp_message = “”

temp = $stdin

temp.each do |f|
smtp_message += f
end

this is runing very well, but when no text is in the pipe, the program
is waiting for input.

my question is, how can i ask, if text in $stdin, without the program is
waitung for input.

ciao

Stefan

Try the -n option

-n assume ‘while gets(); … end’ loop around your
script

#code
smtp_message = “”
$_.each do |f|
smtp_message += f
end
#endcode

cat /var/mailtext| ruby -n send-mail.rb

-rb

3

Am Dienstag, den 25.03.2008, 02:11 +0900 schrieb Rodrigo B.:

#endcode

cat /var/mailtext| ruby -n send-mail.rb

thanks for the answer, but when i start my script is coming the folowing
error

undefined method `each’ for nil:NilClass (NoMethodError)

and my command parser brings failure

ciao

Stefan

4

Am Dienstag, den 25.03.2008, 03:12 +0900 schrieb Rodrigo B.:

did you change ?:

temp.each do |f|
with
$_.each do |f|
–

yes, now i have
$stdin.each do |f| unless $stdin == nil
smtp_message += f
end
end

but when i have nothing in $stdin, the program is waiting

Ciao

Stefan

5

Stefan Gremm wrote:

Am Dienstag, den 25.03.2008, 02:11 +0900 schrieb Rodrigo B.:

#endcode

cat /var/mailtext| ruby -n send-mail.rb

thanks for the answer, but when i start my script is coming the folowing
error

undefined method `each’ for nil:NilClass (NoMethodError)

and my command parser brings failure

ciao

Stefan

did you change ?:

temp.each do |f|
with
$_.each do |f|

6

weird it is working for me…

touch 1
#create empty file

cat 1| 2.rb
: undefined method `each’ for nil:NilClass (NoMethodError)

cat 1| ruby -n 2.rb
#No errors

You need to specify the -n option.

#############

cat 2.rb
smtp_message = “”

$_.each do |f|
smtp_message += f
end
p smtp_message

7

Am Dienstag, den 25.03.2008, 08:50 +0900 schrieb Eric H.:

Here’s one way, but it isn’t foolproof.

$ ruby -e ‘p $stdin.tty?’
true
$ ruby -e ‘p $stdin.tty?’ < /dev/null
false
$ cat /dev/null | ruby -e ‘p $stdin.tty?’
false

eric, thank you for your answer.

But, when starting the program without pipe, the result is true too

Mhmm, my program becoms the messagetext over pipe or over
commandparameter ,if over pipe, all is good, if over parameter, the
program hangs.

Ciao

Stefan

8

On Mar 24, 2008, at 07:51 AM, Stefan Gremm wrote:

my question is, how can i ask, if text in $stdin, without the
program is
waitung for input.

Here’s one way, but it isn’t foolproof.

$ ruby -e ‘p $stdin.tty?’
true
$ ruby -e ‘p $stdin.tty?’ < /dev/null
false
$ cat /dev/null | ruby -e ‘p $stdin.tty?’
false