how to find the amount of space in a directory or the partition directory is in

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

Linux's df will tell you exactly that. To find the free space on the volume a folder resides in, execute:

df -h /home/chris/directory

Output:

Filesystem            Size  Used Avail Use% Mounted on 
server:/vol/home      2.0T  1.3T  759G  63% /home/chris

Omit the -h flag to get raw bytes instead of the human-readable K/M/G/T.

EDIT Just because I'm bored, I went ahead and wrote a script for you:

#!/bin/bash
fillDir='/mnt/fillMe'
musicFile='/home/chris/Yakety Sax.mp3'

while [ `df -P "$fillDir" | awk 'NR==2{print $4}'` -gt 100000000 ]
do
  echo `df -Ph "$fillDir" | awk 'NR==2{print $4}'` space left.
  cp "$musicFile" "$fillDir"
done

Answer 2

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