[PATCH] blktrace bno_plot.py: output comprehensive message when gnuplot not found

[PATCH] blktrace bno_plot.py: output comprehensive message when gnuplot not found

[Eiichi Tsukata]

Currently, bno_plot.py uses os.execvp which does not show enough information
when executed command is not found. For example, when gnuplot is not found
bno_plot.py shows the following messages:

    Traceback (most recent call last):
      File "/usr/local/bin/bno_plot.py", line 123, in <module>
        os.execvp(cmd[0], cmd)
      File "/usr/lib64/python2.7/os.py", line 344, in execvp
        _execvpe(file, args)
      File "/usr/lib64/python2.7/os.py", line 368, in _execvpe
        func(file, *argrest)
    OSError: [Errno 2] No such file or directory

Users can't understand what happend directly from the message.

Instead of os.execvp, this patch uses os.system which shows the following
messages when gnuplot not found:

    sh: gnuplot: command not found

Signed-off-by: Eiichi Tsukata <devel@etsukata.com>
---
 btt/bno_plot.py | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/btt/bno_plot.py b/btt/bno_plot.py
index 19dfdfd..aa92480 100644
--- a/btt/bno_plot.py
+++ b/btt/bno_plot.py
@@ -114,13 +114,12 @@ if __name__ = '__main__':
 
 	pid = os.fork()
 	if pid = 0:
-		cmd = '/usr/bin/gnuplot %s/plot.cmds -' % tmpdir
+		cmd = 'gnuplot %s/plot.cmds -' % tmpdir
 
 		if verbose: print 'Executing %s' % cmd
 
-		cmd = cmd.split(None)
 		os.chdir(tmpdir)
-		os.execvp(cmd[0], cmd)
+		os.system(cmd)
 		sys.exit(1)
 
 	os.waitpid(pid, 0)
-- 
1.8.3.1

Re: [PATCH] blktrace bno_plot.py: output comprehensive message when gnuplot not found

[Jens Axboe]

On Tue, Dec 03 2013, Eiichi Tsukata wrote:
> Currently, bno_plot.py uses os.execvp which does not show enough information
> when executed command is not found. For example, when gnuplot is not found
> bno_plot.py shows the following messages:
> 
>     Traceback (most recent call last):
>       File "/usr/local/bin/bno_plot.py", line 123, in <module>
>         os.execvp(cmd[0], cmd)
>       File "/usr/lib64/python2.7/os.py", line 344, in execvp
>         _execvpe(file, args)
>       File "/usr/lib64/python2.7/os.py", line 368, in _execvpe
>         func(file, *argrest)
>     OSError: [Errno 2] No such file or directory
> 
> Users can't understand what happend directly from the message.
> 
> Instead of os.execvp, this patch uses os.system which shows the following
> messages when gnuplot not found:
> 
>     sh: gnuplot: command not found

Thanks, applied.

-- 
Jens Axboe