Question

I want to write a script that fills a directory with music until there’s a certain amount of space left. The directory may be on various partitions and I don’t know how to ask a directory for free space or it’s partition.

pseudocode
fill(directory)
  until < 100 mb of free space in directory
    copy music to directory

How would you do it using unix tools like bash, find, etc.

Answer 1

I assume you mean you have a specific directory, on a specific partition that you wish to fill until there is only 100 MB left.

The df command will return the amount of disk space left on a given directory’s disk/partition.

df musicfolder/

The fourth column will give free space

Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sda1            151733412  24153792 119871924  17% /

you can use awk to gain the fourth column value and ignore the headers. So your script will be something like:

freespace=$(df /musicfolder | awk 'FNR>1{print $4}')

while [ $freespace -gt 10000000 ] ; do
    (copy files from wherever)
    freespace=$(df ~/musicfolder | awk 'FNR>1{print $4}')
done