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I have a folder that has many files and "rm -rf" takes a lot of time to complete. Is there any faster way to remove a directory and it's contents (subdirs, etc)?

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For anyone interested see: slashroot.in/comment/1286#comment-1286 find trumps perl trumps rsync – Rinzwind Mar 29 at 11:07
up vote 12 down vote accepted

You could try unlinking the inode for the directory but that would leave you with a whole load of orphan files that fsck will flip out about.

rm is as good as it gets.


A few people are mentioning edge cases where some things are faster than others. But let's make sure we're comparing the best versions of the same things.

If you want to delete a directory and everything in it, I'm suggesting you:

rm -rf path/to/directory

rm will internally list the files and directories it's going to delete. And that's all in compiled C. It's those two reasons it's fastest.

This is very pointedly not the same thing as rm -rf path/to/directory/* which will expand at shell level and pass a load of arguments into rm. Then rm has to parse those and then recurse from each. That's much slower.

Just as a "benchmark" that compares find path/to/directory -exec {} \; is nonsense. That runs rm once per file it finds. So slow. Find can xargs-style build commands arguments with -exec rm {} + but that's just as slow as expansion. You can call -delete which uses an internal unlink call to the kernel (like rm does) but that'll only work for files at first.

So to repeat, unless you throw the disk into liquid hot magma, rm is king.


On a related note, different filesystems delete things at different rates because of how they're structured. If you're doing this on a regular basis you might want to store these files in a partition formatted in XFS which tends to handle deletions pretty fast.

Or use a faster disk. If you have tons of RAM, using /dev/shm (a RAM disk) could be an idea.

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You can't actually use the unlink system call on directories (you'll get an EISDIR error), so that first option isn't possible. – James Henstridge Mar 22 '12 at 3:01
    
Would mv to /tmp be faster? It seems that mv takes a lot of time too. – Mohammad Moghimi Mar 22 '12 at 4:35
    
@MohammadMoghimi: mving between different filesystems/partitions means a cp followed by a rm. – enzotib Mar 22 '12 at 6:52
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@enzotib However, if /tmp is on the same filesystem, I wonder if mv and restart would be quicker? I'm not sure if /tmp is cleared using rm anyway. – Sparhawk Nov 15 '13 at 0:23

Sometimes, find $DIR_TO_DELETE -type f -delete is faster than rm -rf.

You may also want to try out mkdir /tmp/empty && rsync -r --delete /tmp/empty/ $DIR_TO_DELETE.

Finally, if you need to delete the content of a whole partition, the fastest will probably be umount, mkfs and re- mount.

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If you don't need the free space the quickest way is delay the deletion and do that in the background:

  • mkdir .delete_me
  • mv big-directory-that-i-want-gone .delete_me

Then have a crontab that does it in the background, at a quiet time, with a low I/O proiority:

3 3 * * * root find /path/to/.delete_me -maxdepth 1 ! -name \. -exec echo rm -rf "{}" +

Notes:

  • check your output before removing the echo in the crontab!
  • the .delete_me directory has to be in the same filesystem - in case it's not obvious to everyone.

Update: I found a neat trick to run multiple rm in parallel - this will help if you have a large disk array:

find target_directory -depth -maxdepth 3 | xargs -d \n -P 5 -n 5 rm -rf
  • -depth to do a depth-first traversal.

  • -maxdepth to limit the depth of the directory traversal so we don't end up listening individual files.

  • -d \n to handle spaces in filenames.

  • -P and -n handles the degree of parallelism (check manpage).

ref: http://blog.liw.fi/posts/rm-is-too-slow/#comment-3e028c69183a348ee748d904a7474019

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Instead of that last command, use find target_dir -maxdepth 3 -depth -type d -print0 | xargs -0 -P 5 rm -rf. The -depth option tells find to list children first. – muru Mar 9 at 23:09

I think the issue is that there is no perfect way to remove a very large directory and its entire set of contents with out a true indexed filing system that understands unlinking and doesn't mean it thinks it has missing files ala FSCK. There has to be a trust.

For instance I have zoneminder running for a golf range. I constructed a linux raid of 1.5 TB to handle the immense amount of data she captures a day ( 12 camera feeds ) how she ran on 120 GB drive is beyond me. Long story short the folder for all the captured data is about 1.4 TB of her storage. Lots to purge

Having to reinstall ZM and purge the 1.4 TB old library is no fun because it can take 1 - 2 days to delete the old images.

A true indexed FS allows the drop of directory and knows that data under it is dead and the zero'ing out the data is a waste of our time and PC resources. It should be an option to zero out deleted data. RM just takes to long in the real world on ext4.

Answer: Recursively unlinking all files would be faster marginally but you would still have to set aside a time to run FSCK.

Create a script running a recursive "FOR" command that can "unlink" all files under your folders then just rm or rmdir all folders to clean it up. Manually run FSCK to zero out the rest of the data when its convenient. Kinda lazy didnt write it out sorry :).

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Albeit not useful if you want to purge an existing directory, I'll mention that a possible strategy if you know you will have a directory with a lof of files which you will need to purge regularly is to put the directory on its own filesystem (e.g., partition). Then when you need to purge it, unmount it, run a mkfs, and remount it. For example OpenBSD advises to do this for /usr/obj, where many files are created during a build of the system, and must be deleted before the next build.

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It would be quite interesting to give us the reason you need it to go faster... (I am not kidding !)

i.e. One reason could be 'you need to free the filled directory for further usage' then if so renaming an recreating the empty directory would be very fast another reason could be 'you locked your terminal during the deleting time' if so you could do the deletion in background while still working... and so on...The more we know the best we could help...

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The directory that I wanted to delete was on our computing cluster and the files were outputs of doing some experiments with many many images. All of a sudden I found out that I'm over quota so I had to either copy them to my pc (copying many files over network is super slow), or simply delete them (which also turned out to be slow). The thing that I did at the end was that I had to create a job (=rm -rf that_dir) and submitted to the cluster to do the deletion which was kind of stupid. – Mohammad Moghimi Mar 22 '12 at 6:53

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