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GNU Core-utils

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2.3 Target directory

Some GNU programs (at least cp, install, ln, and mv) allow you to specify the target directory via this option:

Specify the destination directory.

The interface for most programs is that after processing options and a finite (possibly zero) number of fixed-position arguments, the remaining argument list is either expected to be empty, or is a list of items (usually files) that will all be handled identically. The xargs program is designed to work well with this convention.

The commands in the mv-family are unusual in that they take a variable number of arguments with a special case at the end (namely, the target directory). This makes it nontrivial to perform some operations, e.g., "move all files from here to ../d/", because mv * ../d/ might exhaust the argument space, and ls | xargs ... doesn't have a clean way to specify an extra final argument for each invocation of the subject command. (It can be done by going through a shell command, but that requires more human labor and brain power than it should.)

The --target-directory option allows the cp, install, ln, and mv programs to be used conveniently with xargs. For example, you can move the files from the current directory to a sibling directory, d like this: (However, this doesn't move files whose names begin with `.'.)

ls |xargs mv --target-directory=../d

If you use the GNU find program, you can move all files with this command:
find . -mindepth 1 -maxdepth 1 \
  | xargs mv --target-directory=../d

But that will fail if there are no files in the current directory or if any file has a name containing a newline character. The following example removes those limitations and requires both GNU find and GNU xargs:
find . -mindepth 1 -maxdepth 1 -print0 \
  | xargs --null --no-run-if-empty \
      mv --target-directory=../d

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