linux-kernel - Re: about use wild cards for set_ftrace

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Date:	Thu, 27 Nov 2008 10:34:19 -0500 (EST)
From:	Steven Rostedt <rostedt@...dmis.org>
To:	walimis <walimisdev@...il.com>
cc:	linux-kernel@...r.kernel.org
Subject: Re: about use wild cards for set_ftrace_filter and so on


On Thu, 27 Nov 2008, walimis wrote:

> 
> I encountered an issue when using ftrace.
> We know that we can use wild cards to set set_ftrace_filter, but there's 
> problem when using such as "echo h* > /debug/tracing/set_ftrace_filter".
> If there are files named with "h" prefix in current directory, echo "h*" 
> will echo these files' name to set_ftrace_filter, not "h*".
> For example:
> 
> #cat /debug/tracing/available_filter_functions |grep ^hr |wc -l
> 23
> #ls
> #touch hraa hrdd
> #ls 
> hraa  hrdd
> #echo hr* > /debug/tracing/set_ftrace_filter
> #cat /debug/tracing/set_ftrace_filter
> 
> No output in /debug/tracing/set_ftrace_filter!
> If we use "" to enclose wild cards, it works:
> 
> #ls 
> hraa  hrdd
> #echo "hr*" > /debug/tracing/set_ftrace_filter
> #cat /debug/tracing/set_ftrace_filter |wc -l 
> 23
> 
> This problem can lead to unexpected result if current directory has a 
> lot of files.
> I suppose that we can add some notes to document, so a patch attached.

Using TB? It's best to inline the patch, that way I can comment on it 
better.

Anyway, you should fix the example. I also recommend a single quote over 
double, to prevent any other translation that bash might do.

The example in ftrace.txt should be:

 # echo 'hrtimer_*' > /debug/tracing/set_ftrace_filter


Thanks,

-- Steve

/me goes back to eating turkeys.
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