Find Directories with Two or More Files

With find:

find . -type f -exec sh -c 'SHELL COMMAND' {} \;

This invokes SHELL COMMAND on each found file in turn; the file name is "$0". Thus:

find . -type f -exec sh -c '
    mv "$0" "${0%/*}/$(printf "%s\n" "${0##*/}" | sha1sum | cut -d" " -f1)"
' {} \;

(Note the use of printf rather than echo, in case you have a file called -e or -n or a few other problematic cases that echo mangles.)

You can make this a little faster by invoking the shell in batches.

find . -type f -exec sh -c 'for x; do
      mv "$x" "${x%/*}/$(printf "%s\n" "${x##*/}" | sha1sum | cut -d" " -f1)";
    done' _ {} +

In zsh, there's an easy way to match all the files in the current directory and its subdirectories recursively. The . glob qualifier restricts the matches to regular files, and D includes dot files.

for x in **/*(.D); do mv …; done

In bash ≥4, you can run shopt -s globstar and use **/* to match all files in the current directory and its subdirectories recursively. You'll need to filter regular files in the loop.

shopt -s globstar; GLOBIGNORE=".:.."
for x in **/*; do if [[ -f $x ]]; then mv …; done

You don't need to use awk at all. Use the built-in tests that ksh provides, something like this:

#!/bin/ksh

for NAME in *
do
    FOUND=no
    if [[ -d $NAME && $NAME != '.' && $NAME != '..' ]]
    then
        for SUBNAME in $NAME/*
        do
            if [[ -d $SUBNAME ]]
            then
                FOUND=yes
                break
            fi
        done
        if [[ $FOUND == no ]]
        then
            echo Found only files in $NAME
        fi
    fi
done

That little script looks in all the directories in the current directory, and tells you if they only contain files, no sub-directories.