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On Tuesday 9 June 2009, 16:36, Neil Bothwick wrote: |
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> On Tue, 09 Jun 2009 16:15:21 +0200, Joerg Schilling wrote: |
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> > > find -H /usr/lib /lib -type f | xargs -d'\n' qfile --orphans |
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> > |
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> > No, this is definitely wrong: the right way to handle this is |
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> > execplus (since 19 years). |
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> |
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> If it's been around 19 years, why doesn't Google know anything about |
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> it? What is it? |
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Well, google does not know everything :) |
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Basically, using + instead of ; after -exec allows to run the specified |
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command less times, each time with the highest possible number of |
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arguments (instead of running it once per file, which is what happens |
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with ;). And yes, that's been in POSIX for a long time now. Example: |
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|
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$ ls |
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file1 file2 file3 file4 file5 |
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|
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$ find . -type f -exec sh -c 'echo "number of arguments: $#"' sh {} \; |
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number of arguments: 1 |
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number of arguments: 1 |
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number of arguments: 1 |
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number of arguments: 1 |
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number of arguments: 1 |
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|
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$ find . -type f -exec sh -c 'echo "number of arguments: $#"' sh {} + |
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number of arguments: 5 |
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So when you have to run a command on a very big number of files, say 1000 |
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or more, with ; you spawn 1000 processes, with + you span just one or |
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two (well, depending on the maximum command line length on the system |
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anyway). This is of course much less resource intensive. |
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Basically, using -exec with + does what xargs does, but without the need |
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to care for strange characters in file names (well, a bit simplified, |
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but you get the idea). |
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