I'm a bit stuck with this porblem:
I need to write data to a process and then wait for the exit code of it to
see if it was successful or not.
Now I can IO.popen the process but there is no pclose instance method to
get the exitcode back. Additionally my workaround via Process.waitpid2 does
not work either. I think io.close does already all the cleanup.
e.g.
io = IO.popen(cmd, "w")
io.write(msg)
io.close
pid, status = Process.waitpid2(0)
Raises a "Errno::ECHILD: No child processes" exception.
How do other handle this situation? Do I need to take the hard road via
pipe, fork, exec or did I miss something obvious?
Now I can IO.popen the process but there is no pclose instance method to
get the exitcode back. Additionally my workaround via Process.waitpid2 does
not work either. I think io.close does already all the cleanup.
The $? variable will hold the exit status of the last child to terminate.
andrew
···
On Tue, 21 Mar 2006 01:20:36 +0900, Claudio Jeker <cjeker@diehard.n-r-g.com> wrote:
--
Andrew L. Johnson http://www.siaris.net/
What have you done to the cat? It looks half-dead.
-- Schroedinger's wife
I'm a bit stuck with this porblem:
I need to write data to a process and then wait for the exit code of it to
see if it was successful or not.
Now I can IO.popen the process but there is no pclose instance method to
get the exitcode back. Additionally my workaround via Process.waitpid2 does
not work either. I think io.close does already all the cleanup.
e.g.
io = IO.popen(cmd, "w")
io.write(msg)
io.close
pid, status = Process.waitpid2(0)
Raises a "Errno::ECHILD: No child processes" exception.
How do other handle this situation? Do I need to take the hard road via
pipe, fork, exec or did I miss something obvious?
--
share your knowledge. it's a way to achieve immortality.
- h.h. the 14th dali lama
In article <20060320162018.GG5960@diehard.n-r-g.com>,
Claudio Jeker <cjeker@diehard.n-r-g.com> writes:
I'm a bit stuck with this porblem:
I need to write data to a process and then wait for the exit code of it to
see if it was successful or not.
Now I can IO.popen the process but there is no pclose instance method to
get the exitcode back. Additionally my workaround via Process.waitpid2 does
not work either. I think io.close does already all the cleanup.
$? can be used after close.
I hope this documentation helps.
Index: io.c
···
===================================================================
RCS file: /src/ruby/io.c,v
retrieving revision 1.246.2.97
diff -u -p -r1.246.2.97 io.c
--- io.c 14 Feb 2006 02:23:33 -0000 1.246.2.97
+++ io.c 28 Mar 2006 01:47:15 -0000
@@ -2149,6 +2149,9 @@ rb_io_close(io)
* an <code>IOError</code> is raised if such an attempt is made. I/O
* streams are automatically closed when they are claimed by the
* garbage collector.
+ *
+ * If <em>ios</em> is opened by <code>IO.popen</code>,
+ * <code>close</code> sets <code>$?</code>.
*/
static VALUE
@@ -3062,7 +3065,9 @@ retry:
*
* If a block is given, Ruby will run the command as a child connected
* to Ruby with a pipe. Ruby's end of the pipe will be passed as a
- * parameter to the block. In this case <code>IO::popen</code> returns
+ * parameter to the block.
+ * At the end of block, Ruby close the pipe and sets <code>$?</code>.
+ * In this case <code>IO::popen</code> returns
* the value of the block.
*
* If a block is given with a <i>cmd_string</i> of ``<code>-</code>'',
@@ -3078,6 +3083,7 @@ retry:
* puts "Parent is #{Process.pid}"
* IO.popen ("date") { |f| puts f.gets }
* IO.popen("-") {|f| $stderr.puts "#{Process.pid} is here, f is #{f}"}
+ * p $?
*
* <em>produces:</em>
*
@@ -3086,6 +3092,7 @@ retry:
* Wed Apr 9 08:53:52 CDT 2003
* 26169 is here, f is
* 26166 is here, f is #<IO:0x401b3d44>
+ * #<Process::Status: pid=26166,exited(0)>
*/
On Tue, 21 Mar 2006 01:20:36 +0900, Claudio Jeker > <cjeker@diehard.n-r-g.com> wrote:
[snip]
Now I can IO.popen the process but there is no pclose instance method to
get the exitcode back. Additionally my workaround via Process.waitpid2 does
not work either. I think io.close does already all the cleanup.
The $? variable will hold the exit status of the last child to terminate.
andrew
$? does not work with popen, or open3. I am not sure why one would want to run a process, and monitor the output, yet not care what the exit status is? One would think that this oversite will be fixed in future releases.
Actually I just solved this a few threads below. You can just run
Process.wait after you've done with the IO.popen and it should update
$? with the correct values.
···
On 3/22/06, Shea Martin <null@void.0> wrote:
Andrew Johnson wrote:
> On Tue, 21 Mar 2006 01:20:36 +0900, Claudio Jeker > > <cjeker@diehard.n-r-g.com> wrote:
>
> [snip]
>> Now I can IO.popen the process but there is no pclose instance method to
>> get the exitcode back. Additionally my workaround via Process.waitpid2 does
>> not work either. I think io.close does already all the cleanup.
>
> The $? variable will hold the exit status of the last child to terminate.
>
> andrew
>
$? does not work with popen, or open3. I am not sure why one would want
to run a process, and monitor the output, yet not care what the exit
status is? One would think that this oversite will be fixed in future
releases.
Now I can IO.popen the process but there is no pclose instance method to
get the exitcode back. Additionally my workaround via Process.waitpid2 does
not work either. I think io.close does already all the cleanup.
The $? variable will hold the exit status of the last child to terminate.
andrew
$? does not work with popen, or open3. I am not sure why one would want to run a process, and monitor the output, yet not care what the exit status is? One would think that this oversite will be fixed in future releases.
~S
ps - you can call Process.wait to update $?, but it is not reliable if your program is multi threaded.
···
On Tue, 21 Mar 2006 01:20:36 +0900, Claudio Jeker >> <cjeker@diehard.n-r-g.com> wrote:
$? does not work with popen, or open3. I am not sure why one would want to run a process, and monitor the output, yet not care what the exit status is? One would think that this oversite will be fixed in future releases.
~S
Before I get flamed, know Process.waitpid can be used...
~S