Shell Files Zsh – How to List X Random Files from a Directory

This is not a job for find, since there is no recursion involved.

for x in */C/populate.sh; do
  mkdir -- "${x%%/*}$suffix"
  mkdir -- "${x%%/*}$suffix/C"
  cp -p -- "$x" "./${x%%/*}$suffix/C"
done

Remove the -p option to cp if you don't want to preserve the files' modification time.

To generate a random suffix, BSD/Linux mktemp is as portable as it gets.

suffix=$(mktemp -u tmp_XXXXX)

If you want something vaguely random-looking and POSIX-compliant, this gives a string that changes every second and varies from location to location; you can't really do better with only POSIX tools:

suffix=$({ hostname; pwd; date; } |
         cksum | uuencode -m /dev/stdin | awk 'NR==2 {print substr($0,3,5)}')

If you put this code in a makefile, remember to:

• double all $ signs;
• put all the code on one line, using ; instead to separate shell instructions (you can use backslash+newline+tab to put a line break in the makefile, but that sequence is removed to build the shell command);
• start the shell snippet with set -e, so that it aborts if there is any error.

With zsh and Glob Qualifiers you can easily express it directly, e.g:

echo *(.)

will either only return the list of regular files or an error depending on your configuration.

For the non-directories:

echo *(^/)

(will include symlinks (including to directories), named pipes, devices, sockets, doors...)

echo *(-.)

for regular files and symlinks to regular files.

echo *(-^/)

for non-directories and no symlinks to directories either.

Also, see the D globbing qualifier if you want to include Dot files (hidden files), like *(D-.).