Difference between revisions of "Find notes"
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[[Category:Engineering]] | [[Category:Engineering]] | ||
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| + | == exec versus xargs == | ||
You see some people pipe find output into xargs, but other people start a command using -exec. | You see some people pipe find output into xargs, but other people start a command using -exec. | ||
You wonder what the difference is. The difference is that xargs is faster. It will intelligently group | You wonder what the difference is. The difference is that xargs is faster. It will intelligently group | ||
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You can always do it in a shell loop too: | You can always do it in a shell loop too: | ||
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| + | <pre> | ||
for filename in *.png ; do convert $filename `basename $filename .png`.jpg; done | for filename in *.png ; do convert $filename `basename $filename .png`.jpg; done | ||
| + | </pre> | ||
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| + | == List all extensions in the current directory == | ||
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| + | This came in handy when I was trying to find out exactly what mime-types I need to care about. | ||
| + | |||
| + | <pre> | ||
| + | find . | grep -v .svn | xargs -L 1 basename | sed -e "s/.*\(\\.\\s*\)/\\1/" | sort | uniq | ||
| + | </pre> | ||
Revision as of 12:14, 15 June 2007
exec versus xargs
You see some people pipe find output into xargs, but other people start a command using -exec. You wonder what the difference is. The difference is that xargs is faster. It will intelligently group arguments and feed batches to the subcommand, so it doesn't have to start a new instance of the subcommand for every argument.
Generally I find -exec easier to use because you can easily repeat the found filename in the exec argument. It's easier for me to express exactly what I want to be executed. Of course, some people think the find syntax is wacky. The xargs command comes in handy in other places such as a stream not generated by find, but when using find I stick with -exec unless I have a good reason not to.
You can always do it in a shell loop too:
for filename in *.png ; do convert $filename `basename $filename .png`.jpg; done
List all extensions in the current directory
This came in handy when I was trying to find out exactly what mime-types I need to care about.
find . | grep -v .svn | xargs -L 1 basename | sed -e "s/.*\(\\.\\s*\)/\\1/" | sort | uniq
