Naive sampling of file for bash/zsh

samplf.sh

# Sample file
samplef() {
    # set -x
    if [ -z "${1}" ]; then
        echo 'Error: Missing file path'
        echo
        echo 'Usage:'
        echo 'samplef <FILEPATH> <SAMPLE_SIZE>'
        echo
        echo 'Optional paramters: <SAMPLE_SIZE>, default is 0.1'
        echo 'ex; samplef ./myfile.txt 0.25'
        return
    fi
    SAMPLE_RATIO=${2:-0.1}
    cat $1 | perl -n -e "print if (rand() < $SAMPLE_RATIO)"
}

Just drop in your ~/.bashrc or ~/.zshrc.

To dump random 25% of your file
samplef ./myfile.txt 0.25

Defaults to dumping10 percent of your file
samplef ./myfile.txt

Credit goes to http://stackoverflow.com/a/692317/3538289