How to Safely Clear Linux RAM Cache and Swap Space (Step‑by‑Step Guide)

How to clear cache in Linux?

Linux provides three options to drop caches without stopping any processes or services. sync; echo 1 > /proc/sys/vm/drop_caches 1. Drop only page cache. sync; echo 2 > /proc/sys/vm/drop_caches 2. Drop dentries and inodes. sync; echo 3 > /proc/sys/vm/drop_caches 3. Drop page cache, dentries, and inodes.

The sync command flushes filesystem buffers; the echo writes to the kernel drop‑caches interface. Using option 1 is safest in production because it only clears page cache. Option 3 clears everything and can degrade performance if used indiscriminately.

Automating cache clearing with cron

Create a shell script clearcache.sh containing the desired command, for example:

#!/bin/bash
# Recommended: use echo 1 to clear only page cache
sync; echo 1 > /proc/sys/vm/drop_caches

Make the script executable: chmod 755 clearcache.sh Add a cron job to run it daily at 2 PM:

# crontab -e
0 14 * * * /path/to/clearcache.sh

Automatic cache clearing should be used only when you fully understand the workload; doing it blindly can cause a production server to reload data from disk and potentially crash under load.

How to clear Linux swap space?

To drop swap, run: swapoff -a && swapon -a You can combine cache and swap clearing in one script:

# Clear caches and swap safely
sync; echo 1 > /proc/sys/vm/drop_caches && swapoff -a && swapon -a && printf '
%s
' 'Ram-cache and Swap Cleared'

Before and after running the script, you can verify memory usage with free -m.