Skip to main content

Linux deleted log file doesn't free up the disk space

TL DR;

Kill or restart the process which writes the log file. Even though the file is deleted, it won't free up the disk space if the process is still writing to the log file. Only after stopping the process, it will actually be deleted.

----------------------------------------------------------------------------------------


Usually, disk spaces of servers are getting cluttered and filled by application log files when a proper log rotation mechanism is not implemented. 

In case if you find such a log file causing the disk space to fill up 100%, it will probably impact any application which trying to use the disk. 

You can see the disk space by the following command.

df -h

If the root dir ("/") usage is 100% the impact may be high for the system. Or else, if there is more than one disk attached then any application that uses that disk can be impacted. 

In the above image, mine is not filled yet. I have only used 25% of the disk.


How to find what files are using the disk space more?

You can use the "du" command to do that. 
Go to the root dir ("/") in the terminal
cd /
Then use the below command to figure out the directory which uses the most disk space.
sudo du -d 1 -h .

This command gives an estimate of the file space usage of the directories.

Since we are scanning from the root dir, you will need the sudo powers to access some directories.

-d is used to mention the depth. When scanning the files how deep it should scan over the directory structure. -d 1 means you should scan the immediate directories only.

-h says show the output in the human-readable figures. So, it will show the size in Gb or Mb values.

Finally, the directory which we tell it to scan, we have given a dot (".") to say "current directory".



It may provide some errors saying cannot access some directory or files, because we are trying to scan some paths where they are being actively used by the OS. Therefore some paths, it won't allow you to scan just like that, but don't worry about it, our cluttering files won't be there anyway.

When you find the directory which has the most usage, then go inside it, in my case /opt is taking more space. Then run the same "du" command once again. 
You can find the directories like that and go inside them. If you can't find any other directories inside a directory, then you have to use the ls -alh command to see the files and their size.

If you find the log file which clutters the disk space, you can just delete it using an "rm" command.

Problem: deleted log file still doesn't free up the disk space

Let us say you already found the problematic file and deleted it using the rm command.
Sometimes even after that, if you check the df -h it still shows 100% usage.

Solution

Kill or restart the process which writes the log file. Even though the file is deleted, it won't free up the disk space if the process is still writing to the log file. Only after stopping the process, it will actually be deleted.

Labels

Labels:

Comments

Post a Comment

Popular posts from this blog

Install Docker on Windows 11 with WSL Ubuntu 22.04

This is to install Docker within Ubuntu WSL without using the Windows Docker application. Follow the below steps. Install Ubuntu 22.04 WSL 1. Enable Windows Subsystem for Linux and Virtual Machine platform Go to Control Panel -> Programs -> Programs and Features -> Turn Windows features on or off 2. Switch to WSL 2 Open Powershell and type in the below command. wsl --set-default-version 2 If you don't have WSL 2, download the latest WSL 2 package and install it.  3. Install Ubuntu Open Microsoft Store and search for Ubuntu. Select the version you intend to install. I'd use the latest LTS version Ubuntu 22.04. Click on the Get button. It will take a couple of minutes to download and install. 4. Open up the installed Ubuntu version that was installed. If you get an error like the below image, make sure to install the WSL2 Kernel update .  If it's an older Ubuntu version the error message would be something like the image below. Error: WSL 2 requires an update to its ...
1 comment
Read more

Java, how to create a list with a single element

 I wanted to create a Java List with a single element. Yet, I wanted to add more elements later. So, I was looking for a couple of ways to do this. So far there are multiple elegant ways to create a list with a single element with a one-liner. Not so much for a modifiable list though. Here's what I gathered so far. Followings are a few ways of creating a list with strictly a single entry. Can't add more elements. 1. Collections.singletonList() This returns an immutable list that cannot be modified or add more elements. // An immutable list containing only the specified object. List<String> oneEntryList = Collections. singletonList ( "one" ) ; oneEntryList.add( "two" ) ; // throws UnsupportedOperationException 2.  Arrays.asList() This returns a fixed-size list consisting of the number of elements provided as arguments. The number of elements provided would be an array hence the size is fixed to the length of the array. // Returns a fixed-size list List...
Post a Comment
Read more

How to fix SSLHandshakeException PKIX path building failed in Java

TL ; DR 1. Extract the public certificate of the website/API that you are trying to connect from your Java application. Steps are mentioned in this post 2. Use the Java keytool to install the extracted certificate into the "cacerts" file (Trust store) keytool -import -trustcacerts -alias <domain name> -file <public certificate>.cert -keystore /path_to_java_home/jre/lib/security/cacerts -storepass changeit 3. Restart your Java application Exception A typical exception stack trace would look like below. javax.net.ssl. SSLHandshakeException : sun.security.validator.ValidatorException: PKIX path building failed : sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target at sun.security.ssl.Alerts.getSSLException(Alerts.java:192) at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1959) at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:302) at sun.security.ssl.Handshake...
Post a Comment
Read more