randcopy

#!/usr/bin/env bash
# Don't ask me why I wrote this.
# Suffice to say I'm a total sperg.

# Setup
mkdir subset_dir
ls -1 > list.txt

# Create list of 30 random files
for ((i=0; $i<30; i++)); do
    declare -i length=$(wc -l list.txt | cut -d ' ' -f 1)
    declare -i r=$RANDOM%$length+1
    sed -n "${r}p" list.txt >> sublist.txt
done

# Remove dublicates
cat sublist.txt | sort | uniq > subsublist.txt
let length=$(wc -l subsublist.txt | cut -d ' ' -f 1)

# Copy files from list
for ((i=1; $i<=$length; i++)); do
    file=$(sed -n "${i}p" subsublist.txt)
    cp $file subset_dir
done

# Cleanup
rm list.txt sublist.txt subsublist.txt
unset i length file