Check free disk space for current partition in bas

Question

I am writing an installer in bash. The user will go to the target directory and runs the install script, so the first action should be to check that there is enough space. I know that df will report all file systems, but I was wondering if there was a way to get the free space just for the partition that the target directory is on.

Edit - the answer I came up with

df $PWD | awk '/[0-9]%/{print $(NF-2)}'

Slightly odd because df seems to format its output to fit the terminal, so with a long mount point name the output is shifted down a line

Answer 1

1. df command : Report file system disk space usage
2. du command : Estimate file space usage

Type df -h or df -k to list free disk space:

 $ df -h

OR

 $ df -k

du shows how much space one or more files or directories is using:

 $ du -sh

The -s option summarizes the space a directory is using and -h option provides Human-readable output.

Answer 2

I think this should be a comment or an edit to ThinkingMedia's answer on this very question (Check free disk space for current partition in bash), but I am not allowed to comment (not enough rep) and my edit has been rejected (reason: "this should be a comment or an answer"). So please, powers of the SO universe, don't damn me for repeating and fixing someone else's "answer". But someone on the internet was wrong!™ and they wouldn't let me fix it.

The code

  df --output=avail -h "$PWD" | sed '1d;s/[^0-9]//g'

has a substantial flaw: Yes, it will output 50G free as 50 -- but it will also output 5.0M free as 50 or 3.4G free as 34 or 15K free as 15.

To create a script with the purpose of checking for a certain amount of free disk space you have to know the unit you're checking against. Remove it (as sed does in the example above) the numbers don't make sense anymore.

If you actually want it to work, you will have to do something like:

FREE=`df -k --output=avail "$PWD" | tail -n1`   # df -k not df -h
if [[ $FREE -lt 10485760 ]]; then               # 10G = 10*1024*1024k
     # less than 10GBs free!
fi;

Also for an installer to df -k $INSTALL_TARGET_DIRECTORY might make more sense than df -k "$PWD". Finally, please note that the --output flag is not available in every version of df / linux.