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Improving Efficiency
When the -exec action is used, it launches a new instance of the specified command each time a matching file is found. There are times when we might prefer to combine all of the search results and launch a single instance of the command. For example, rather than executing the commands like this:
ls -l file1
ls -l file2
we may prefer to execute them this way:
ls -l file1 file2
thus causing the command to be executed only one time rather than multiple times. There are two ways we can do this. The traditional way, using the external command xargs and the alternate way, using a new feature in find itself. We’ll talk about the alternate way first.
By changing the trailing semicolon character to a plus sign, we activate the ability of find to combine the results of the search into an argument list for a single execution of the desired command. Going back to our example, this:
find ~ -type f -name 'foo*' -exec ls -l '{}' ';'
find ~ -type f -name 'foo*' -exec ls -l '{}' ';'
-rwxr-xr-x 1 me
-rw-r--r-- 1 me
-rwxr-xr-x 1 me
-rw-r--r-- 1 me
me 224 2007-10-29 18:44 /home/me/bin/foo
me 224 2007-10-29 18:44 /home/me/bin/foo
me
me
0 2016-09-19 12:53 /home/me/foo.txt
0 2016-09-19 12:53 /home/me/foo.txt
will execute ls each time a matching file is found. By changing the command to:
find ~ -type f -name 'foo*' -exec ls -l '{}' +
find ~ -type f -name 'foo*' -exec ls -l '{}' +
-rwxr-xr-x 1 me
-rw-r--r-- 1 me
-rwxr-xr-x 1 me
-rw-r--r-- 1 me
me 224 2007-10-29 18:44 /home/me/bin/foo
me 224 2007-10-29 18:44 /home/me/bin/foo
me
me
0 2016-09-19 12:53 /home/me/foo.txt
0 2016-09-19 12:53 /home/me/foo.txt
we get the same results, but the system only has to execute the ls command once.