How to add progress bar to a somearchive.tar.xz extract

Question

I'd like to print at the very least print # files extracted, from running a tarball extract

xz -dc /path/to/somearchive.tar.xz | sudo tar xvpf - -C /path/to/some_directory

I was thinking of using the "\r" as mentioned in this question, for instance

num=0
when [\n received]
    num=$(($num + 1))
    echo -ne "$num files extracted \r"
end when

my bash skills fail me.

Answer 1

Using pv to pipe the file to tar.

1. Firstly, you'll need to install pv, which on macOS can be done with:

   brew install pv
   

   On Debian or Ubuntu, it can be done with: apt install pv (Thanks @hyperbola!).

2. Pipe the compressed file with pv to the tar command:

   pv mysql.tar.gz | tar -xz   
   

Here's the sample output of this command:

For those curious, this works by pv knowing the total file size of the file you pass it and how much of it has been "piped" to the tar command. It uses those two things to determine the current progress, the average speed, and the estimated completion time. Neat!

Answer 2

When extracting with tar you can use the --checkpoint option. What you get is not really a progress bar but good enough to see the progress.

In this example, tar will print a message each 100 records written. If you place a dot immediately after the equal sign, it will just print a ..

tar -xf somearchive.tar.gz --checkpoint=.100

Output:

.......

Answer 3

If you really want to do it by file you could use:

tar xvpf /path/to/archive.tar.xz -C /path/to/dir 2>&1 | 
while read line; do
    x=$((x+1))
    echo -en "$x extracted\r"
done

Notes:

• You probably don't need to xz separately, most tar implementations will automatically detect and decompress it for you.
• tar reads from stdin by default, you don't need f -.

You should look into using pv instead, it's more precise and more generally applicable:

pv /path/to/archive.tar.xz | tar xp -C /path/to/dir

Answer 4

While the pv solution shows progress nicely, it doesn't show what files are extracted whereto. The --checkpoint=.100 option shows the files and indicates that it's working, but doesn't show progress.

On the Tar Checkpoints page I found some information about the --checkpoint-action option, which is able to execute some bash magic for every checkpoint. Knowing that a checkpoint is created every 20 blocks of 512 bytes (at least that's the default, see man tar), It's possible to get the progress based on the current block and the original size.

The snippet below can be saved as a bash file (or put into a bash function):

archive="$1"

originalsize=$(file $archive | rev | cut -d' ' -f1 | rev)
step=100
blocks=$(echo "$originalsize / 512 / 20 / $step" | bc)

tar -xvz --checkpoint=$step --totals \
 --checkpoint-action="exec='p=\$(echo "\$TAR_CHECKPOINT/$blocks" | bc -l);printf \"%.4f%%\r\" \$p'" \
 -f $archive

Then using it is very straightforward:

bash tarprogress.sh your.archive.tgz

Answer 5

You can do this with xz files like this:

unxz -v --stdout file.tar.xz | tar -x