Piping `find` to 'tail`

Hari K Published at Dev

Hari K

I want to get the last two lines of the find output and copy them somewhere. I tried

find . -iname "*FooBar*" | tail -2 -exec cp "{}" dest \;

but the output was "invalid option --2" for tail.

Also, my file or directory name contains spaces.

l0b0

The following should work on absolutely any paths.

Declare a function to be able to use head and tail on NUL-separated output:

nul_terminated() {
    tr '\0\n' '\n\0' | "$@" | tr '\0\n' '\n\0'
}

Then you can use it to get a NUL-separated list of paths from your search after passing through tail:

find . -exec printf '%s\0' {} \; | nul_terminated tail -n 2

You can then pipe that to xargs and add your options:

find . -iname "*FooBar*" -exec printf '%s\0' {} \; | nul_terminated tail -n 2 | xargs -I "{}" -0 cp "{}" "dest"

Explanation:

find files in the current directory (.) and below with a name containing foobar (case insensitive because of the i in -iname);
for each file, run (-exec) a command to
print each file path ({}) followed by a NUL character (\0) individually (\;);
swap newlines and NUL characters (tr '\0\n' '\n\0');"
get the last two lines (that is, paths; tail -n 2, "$@");
swap newlines and NUL characters again to get a NUL-separated list of file names (tr '\0\n' '\n\0').

The xargs command is a bit harder to explain. It builds as many cp ... "dest" commands as necessary to fit in the maximum command length of the operating system, replacing the {} token in the command with the actual file name (-I "{}" ... "{}"), using the NUL character as a separator when reading the parameters (-0).

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