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Re: [OT] Cleaning up the output of a multiple file rename (bash)



sean finney <seanius@seanius.net> [2003-01-02 19:21:14 -0500]:
> instead of using date +%s, incrementing, and sleep, how about 
> using date +%s%N?  what you can do is something like

Interesting suggestion.  Note that %N is only available in the sid
version in coreutils and not the stable woody version.  It is a new
feature.

> while [ ! $doneyet ]; do
> 	FN="`date +%s%N`.jpg"
> 	[ ! -f $FN ] && doneyet=1;
> done

> - if there is a collision, it simply tries again immediately (and will
>   get a new value from %N)

But if there is a lot of activity then this will 'spinlock' until it
generates a new filename.  There is no sleep there or anything so it
will keep spinning at full cpu until the time changes to a unique
name.  The faster the cpu the more cycles available to spin.  And if
there were several mail processes arriving at the same time this is
even likely.  Therefore I don't like it as much.

Half baked idea: How about using 'mktemp'?  If all you are looking for
is a temporary filename then that command will provide unique names
without this set of problems.  By default in /tmp but you can always
put it in the current directory with 'mktemp -p ./'.

Bob

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