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Am 27.02.2011 21:09, schrieb hamilton: |
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> On Sun, 27 Feb 2011 21:01:46 +0100, Florian Philipp wrote: |
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>> Hi list! |
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>> |
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>> I'm currently streamlining some of my shell scripts to avoid unnecessary |
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>> process calls where bash itself is powerful enough. |
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> |
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> My experience (take it for whatever you think it's worth) is that |
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> doing so often just makes things harder to follow and maintain. |
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> It's very unlikely that the overhead of a fork+exec is appreciably |
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> slowing your process down. Having said that (and in that vein) there |
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> is something more straightforward which may be useful: |
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> |
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Oh, I completely agree with you. In 90% of all cases, simple and clean |
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code is preferable. And if I really card about performance, I'd use C or |
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Perl. However, there are still such rare cases where everything works |
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fine and you see no reason to code it all again but those three forks in |
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the innermost loop just kill your performance. |
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In such cases, I optimize it and put the clean version in the comments. |
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That way, clarity doesn't suffer too much. |
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> [...] |
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> |
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>> My current solution is using two string operations: |
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>> string='foo:bar:foo' |
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>> # remove everything up to and including first ':' |
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>> second_and_following=${string#*:} |
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>> # remove everything from the first ':' following |
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>> second_field=${second_and_following%%:*} |
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> |
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> second_field = $(echo $string | awk -F: '{print $2}') |
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> |
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> |
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Regards, |
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Florian Philipp |
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