Create a file of a specific size with random printable strings in bash

Question

I want to create a file of a specific size containing only printable strings in bash.

My first thought was to use /dev/urandom:

dd if=/d         


        

Answer 1

What about this?

size=1048576 # 1MB
fname="strings.txt"

while read line ; do
    # Append strings to the file ...
    strings <<< "${line}" >> "${fname}"
    fsize="$(du -b "${fname}" | awk '{print $1}')"
    # ... until it is bigger than the desired size
    if [ ${fsize} -gt ${size} ] ; then
        # Now truncate the file to the desired size and exit the loop
        truncate -s "${size}" strings.txt
        break
    fi 
done < /dev/urandom

I admit that it is not very efficient. I faster attempt would be to use dd:

size=1048576
fname="strings.txt"

truncate -s0 "${fname}"

while true ; do
    dd if=/dev/urandom bs="${size}" count=1 | strings >> "${fname}"
    fsize="$(du -b "${fname}" | awk '{print $1}')"
    if [ ${fsize} -gt ${size} ] ; then
        truncate -s "${size}" strings.txt
        break
    fi
done