Linux Server Running Out of Space? 😱 Super Simple Solution: Find and Delete the Largest Files

Hello! Today, we’re going to learn how to solve the ‘disk space shortage’ problem that anyone operating a Linux server will encounter at some point. A terrifying situation where the service suddenly stops or you can’t connect to the server! 😨 Most of the time, this problem occurs because the disk space is full.

In such cases, as a temporary measure, finding and deleting the largest files can help you put out the urgent fire. I’ll explain the method step-by-step now!

Step 1: Check Filesystem Usage 📊

First, you need to identify which disk is causing the problem. The `df` command allows you to see the overall filesystem usage of your current server at a glance.

1. Connect to the server where the problem occurred. (Example: node01)

ssh node01

1. Use the `-h` option (human-readable) to check usage in units that are easy for humans to read (GB, MB).[Example Output]Look closely at the results. The Use% column exceeding 90% is our target. In the example above, the root (`/`) filesystem usage is 98%.
2. ⚠️ Important! The path to be used in subsequent steps is the one in the ‘Mounted on’ column. In the example above, it would be `/`. Be sure to remember the path that matches your environment. For convenience, in this article, I will refer to it as `/path/to/mountpoint`.

`

df -h

`

Step 2: Find the Largest File (Don’t Delete Yet!) 🔍

Now it’s time to find out which file is occupying the most space in the full filesystem (`/` or `/data`, etc.).

Deleting first is dangerous! 🚨 It’s important to get into the habit of checking what kind of file it is first. The command below only shows the size and path of the largest file.

find /path/to/mountpoint -type f -printf '%s %p
' | sort -nr | head -n 1

The command looks a bit long and complicated, doesn’t it? Let me break it down for you.

• find /path/to/mountpoint -type f -printf ‘%s %p

‘:

• find: Searches for files in a specific path.
• -type f: Finds only ‘files’, not directories.
• -printf ‘%s %p

‘: Prints the information of the found file in a specific format. %s means file size, %p means file path. That is, it outputs in the format [file size] [file path].

• | (pipe): A connector that passes the output of the left command as input to the right command.
• sort -nr:
• sort: Sorts the received content.
• -n: Sorts numerically.
• -r: Reverse order, i.e., descending. The largest number will be at the top.
• head -n 1: Shows only the first line of the received content.

As a result, this command means: “Find the single largest file in the specified path and show its size along with its path!”

Step 3: Confirm and Delete the Largest File 🗑️

If you are confident that the file found in Step 2 is a safe file to delete, such as an unnecessary log file or backup file, then proceed with deletion.

The command below adds the deletion logic to the Step 2 command.

find /path/to/mountpoint -type f -printf '%s %p
' | sort -nr | head -n 1 | awk '{print $2}' | xargs rm

Let’s look at the newly added parts:

• awk ‘{print $2}’:
• awk: A powerful text processing tool.
• ‘{print $2}’: Means to print only the second column from the input. It extracts only the file path from input in the format [file size] [file path].
• xargs rm:
• xargs: Passes the result from the previous command (file path) as an argument to the `rm` command.
• rm: The command to delete files.

In other words, the process of finding the path of the largest file and deleting it with the `rm` command is automatically executed.

💥 Caution! 💥 This command permanently deletes files without confirmation. Deleting files essential for system operation may prevent the server from booting. Always double-check what kind of file it is and if it’s safe to delete before proceeding!

Step 4: Confirm Space Has Been Freed ✅

If you’ve successfully deleted the file, you need to confirm that disk space has actually been freed, right? Let’s run the `df -h` command again, which we used in Step 1.

df -h /path/to/mountpoint

This time, instead of looking at the entire filesystem, it’s more convenient to check only the specific path we worked on.

[Example Output]

Filesystem      Size  Used Avail Use% Mounted on
/dev/sda1        50G   42G  7.5G  85% /

You can see that Use% has significantly dropped from 98% to 85%. Success! 🎉 The server has now regained space and can operate normally again.

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Today, we learned step-by-step how to find and delete the largest files when a Linux server’s disk space is full. This method is very useful in an emergency, but it may not be a fundamental solution. It’s more important to establish long-term plans, such as regularly cleaning up unnecessary logs or increasing disk capacity! 😊