Tracking down where disk space has gone on Linux?

Question

When administering Linux systems I often find myself struggling to track down the culprit after a partition goes full. I normally use du / | sort -nr but on a large filesystem this takes a long time before any results are returned.

Also, this is usually successful in highlighting the worst offender but I've often found myself resorting to du without the sort in more subtle cases and then had to trawl through the output.

I'd prefer a command line solution which relies on standard Linux commands since I have to administer quite a few systems and installing new software is a hassle (especially when out of disk space!)

Solution 1

Try ncdu, an excellent command-line disk usage analyser:

Solution 2

Don't go straight to du /. Use df to find the partition that's hurting you, and then try du commands.

One I like to try is

# U.S.
du -h <dir> | grep '[0-9\.]\+G'
# Others
du -h <dir> | grep '[0-9\,]\+G'

because it prints sizes in "human readable form". Unless you've got really small partitions, grepping for directories in the gigabytes is a pretty good filter for what you want. This will take you some time, but unless you have quotas set up, I think that's just the way it's going to be.

As @jchavannes points out in the comments, the expression can get more precise if you're finding too many false positives. I incorporated the suggestion, which does make it better, but there are still false positives, so there are just tradeoffs (simpler expr, worse results; more complex and longer expr, better results). If you have too many little directories showing up in your output, adjust your regex accordingly. For example,

grep '^\s*[0-9\.]\+G'

is even more accurate (no < 1GB directories will be listed).

If you do have quotas, you can use

quota -v

to find users that are hogging the disk.

Solution 3

For a first look, use the “summary” view of du:

du -s /*

The effect is to print the size of each of its arguments, i.e. every root folder in the case above.

Furthermore, both GNU du and BSD du can be depth-restricted (but POSIX du cannot!):

• GNU (Linux, …):

  du --max-depth 3
  

• BSD (macOS, …):

  du -d 3
  

This will limit the output display to depth 3. The calculated and displayed size is still the total of the full depth, of course. But despite this, restricting the display depth drastically speeds up the calculation.

Another helpful option is -h (words on both GNU and BSD but, once again, not on POSIX-only du) for “human-readable” output (i.e. using KiB, MiB etc.).

Solution 4

You can also run the following command using du:

~# du -Pshx /* 2>/dev/null

• The -s option summarizes and displays total for each argument.
• -h prints Mio, Gio, etc.
• -x = stay in one filesystem (very useful).
• -P = don't follow symlinks (which could cause files to be counted twice for instance).

Be careful with -x, which will not show the /root directory if it is on a different filesystem. In that case, you have to run du -Pshx /root 2>/dev/null to show it (once, I struggled a lot not pointing out that my /root directory had gone full).

Solution 5

Finding the biggest files on the filesystem is always going to take a long time. By definition you have to traverse the whole filesystem looking for big files. The only solution is probably to run a cron job on all your systems to have the file ready ahead of time.

One other thing, the x option of du is useful to keep du from following mount points into other filesystems. I.e:

du -x [path]

The full command I usually run is:

sudo du -xm / | sort -rn > usage.txt

The -m means return results in megabytes, and sort -rn will sort the results largest number first. You can then open usage.txt in an editor, and the biggest folders (starting with /) will be at the top.

View more solutions

Comments

[Admin]

It can also scan remote folders via SSH, FTP, SMB and WebDAV.

[Admin]

That's only Konqueror 3.x though - the file size view still hasn't been ported to KDE4.

[SamB]

Thanks for pointing out the -x flag!

[pataka]

This is very quick, simple and practical

[thegreendroid]

This command did the trick to find a hidden folder that seemed to be increasing in size over time. Thanks!

[ReactiveRaven]

if du complains about -d try --max-depth 5 in stead.

[Admin]

Great anwser. Seems correct for me. I suggest du -hcd 1 /directory. -h for human readable, c for total and d for depth.

[jchavannes]

grep '[0-9]G' contained a lot of false positives and also omitted any decimals. This worked better for me: sudo du -h / | grep -P '^[0-9\.]+G'

[jchavannes]

@BenCollins I think you also need the -P flag for Perl regex.

[Ben Collins]

@jchavannes -P is unnecessary for this expression because there's nothing specific to Perl there. Also, -P isn't portable to systems that don't have the GNU implementation.

[jchavannes]

Ahh. Well having a carat at the beginning will remove false positives of directories which have a number followed by a G in the name, which I did.

[Polyphil]

Is this in bytes?

[Vitruvie]

In case you have really big directories, you'll want [GT] instead of just G

[CMCDragonkai]

Is there a tool that will continuously monitor disk usage across all directories (lazily) in the filesystem? Something that can be streamed to a web UI? Preferably soft-realtime information.

[Admin]

when i try to ./configure this, it tells me a required header is missing

[Siddhartha]

You could do du -Sh to get a human readable output.

[Mike]

du -Pshx .* * 2>/dev/null + hidden/system directories

[timelmer]

This is great. Some things just work better with a GUI to visualize them, and this is one of them! I need an X-server on my server anyways for CrashPlan, so it works on that too.

[Admin]

Typically, I hate being asked to install something to solve a simple issue, but this is just great.

[ndemou]

It's a pity that a dozen of grep hacks are more upvoted. Oh and du -k will make it absolutely certain that du is using KB units

[Mark Borgerding]

Good idea about the -k. Edited.

[dave_thompson_085]

Even simpler and more robust: du -kx $2 | awk '$1>'$(($1*1024)) (if you specify only a condition aka pattern to awk the default action is print $0)

[ndemou]

Good point @date_thompson_085. That's true for all versions of awk I know of (net/free-BSD & GNU). @mark-borgerding so this means that you can greatly simplify your first example to just du -kx / | awk '$1 > 500000'

[ndemou]

@mark-borgerding: If you have just a few kBytes left somewhere you can also keep the whole output of du like this du -kx / | tee /tmp/du.log | awk '$1 > 500000'. This is very helpful because if your first filtering turns out to be fruitless you can try other values like this awk '$1 > 200000' /tmp/du.log or inspect the complete output like this sort -nr /tmp/du.log|less without re-scanning the whole filesystem

[Mark Borgerding]

Regarding the simplification -- I think that kills clarity to save a few characters.

[Mark Borgerding]

Regarding saving the whole du output, -- That "few kBytes" could easily be many megabytes if the volume contains millions of files. That seems dangerous under the presumable circumstances.

[jonathanccalixto]

I'm use du -hd 1 <folder to inspect> | sort -hr | head

[Admin]

Install size is 81k... And it's super easy to use! :-)

[pahariayogi]

'du -sh * | sort -h ' works perfectly on my Linux (Centos distro) box. Thanks!

[Admin]

I was looking for a fast way to find what takes up disk space in an ordered way. This tool does it and it also provides sorting and easy navigation. Thank you for the reference.

[user2948306]

Using du -s means this will print a total size for / and nothing else.

[ndemou]

This tool doesn't match two main points of the question "I often find myself struggling to track down the culprit after a partition goes full" and "I'd prefer a command line solution which relies on standard Linux commands"

[ndemou]

Good point but this should be a comment and not an answer by itself - this question suffers from too many answers

[ndemou]

Note this part of the question: "I'd prefer a command line solution which relies on standard Linux commands since..."

[ndemou]

Don't use grep for arithmetic operations -- use awk instead: du -k | awk '$1 > 500000'. It is much easier to understand, edit and get correct on the first try.

[Admin]

sudo apt install ncdu on ubuntu gets it easily. It's great

[Admin]

You quite probably know which filesystem is short of space. In which case you can use ncdu -x to only count files and directories on the same filesystem as the directory being scanned.

[srghma]

du --max-depth 5 -h /* 2>&1 | grep '[0-9\.]\+G' | sort -hr | head to filter Permission denied

[B. Shea]

"finding biggest takes long time.." -> Well it depends, but tend to disagree: doesn't take that long with utilities like ncdu - at least quicker than du or find (depending on depth and arguments)..

[Admin]

@Alf47 Required header for what? You list only partial error. You are missing a lib dependency. Maybe try installing ncurses lib. That seems to be the usual culprit. The info is there in the build output on what your system is missing. see: unix.stackexchange.com/a/113493/186861

[vimal krishna]

I find this to be the best answer, to detect the large sized in sorted order

[Admin]

@bshea had a great suggestion, many times on AWS it's only your root filesystem that is small, everything else is an EBS or EFS mount that is huge, so you only need to find and clean the root partition.

[Clare Macrae]

@Siddhartha If you add -h, it will likely change the effect of the sort -nr command - meaning the sort will no longer work, and then the head command will also no longer work

[Admin]

I have so little space that I can't install ncdu

[oarfish]

On Ubuntu, I need to use -h to du for human readable numbers, as well as sort -h for human-numeric sort. The list is sorted in reverse, so either use tail or change order.

[Bruno]

since I prefer not to be root, I had to adapt where the file is written : sudo du -xm / | sort -rn > ~/usage.txt

[Admin]

Hands down the best. ncdu is an amazing and beautiful tool!

[Admin]

Error, can't install ncdu, E: You don't have enough free space in /var/cache/apt/archives/. :(

[Admin]

Problem is... ran out of disk space so can't install another dependency :)

[Admin]

This is like WinDirStat for Linux users - absolutely perfect for evaluating disk consumption and treating out-of-control scenarios.

[Admin]

If you can't use a GUI (like you're on a remote server), ncdu -e works nicely. Once the display opens up, use m then M to display and sort by mtime, while the (admittedly small) percentage graph is still there to get you an idea of the size.

[chrishollinworth]

"If you can't use a GUI (like you're on a remote server)," - why does a remote server prevent you from using a gui?

[Atralb]

/root/shows without issues. Why would it not be shown ?

[Admin]

Pressing r when browsing disk usage refreshes current directory

[WBT]

Can't run Java on Linux?

[Faither]

The OP asked for a CLI version

[WBT]

OP said that was preferred, not required; questions closed as duplicates of this don't have the same preference.

[Admin]

Best answer imho

[Admin]

no sudo, no problem: wget -qO- https://dev.yorhel.nl/download/ncdu-linux-x86_64-1.16.tar.gz | tar xvz && ncdu -x (official builds)

[Admin]

no space, no problem: sudo mkdir /ncdu && sudo mount -t tmpfs -o size=500m tmpfs /ncdu && wget -qO- https://dev.yorhel.nl/download/ncdu-linux-x86_64-1.16.tar.gz | tar xvz --directory /ncdu && /ncdu/ncdu -x

[Admin]

no space, no sudo, no problem: wget -qO- https://dev.yorhel.nl/download/ncdu-linux-x86_64-1.16.tar.gz | tar xvz --directory /dev/shm && /dev/shm/ncdu -x ... urls might change, newer version might be available see here: dev.yorhel.nl/ncdu