{"id":784,"date":"2022-01-14T14:02:02","date_gmt":"2022-01-14T14:02:02","guid":{"rendered":"https:\/\/mailinvest.blog\/index.php\/2022\/01\/14\/how-to-view-and-monitor-disk-space-usage-from-the-linux-command-line-cloudsavvy-it\/"},"modified":"2022-01-14T14:02:02","modified_gmt":"2022-01-14T14:02:02","slug":"how-to-view-and-monitor-disk-space-usage-from-the-linux-command-line-cloudsavvy-it","status":"publish","type":"post","link":"https:\/\/mailinvest.blog\/index.php\/2022\/01\/14\/how-to-view-and-monitor-disk-space-usage-from-the-linux-command-line-cloudsavvy-it\/","title":{"rendered":"How to View and Monitor Disk Space Usage From the Linux Command Line \u2013 CloudSavvy IT"},"content":{"rendered":"

<\/a>\n<\/p>\n

\n

\"Bash<\/p>\n

While it\u2019s usually pretty clear if your system is running out of memory or using too much CPU time, disk usage is another key metric that can sneak up on you over time if you leave your server unattended. You\u2019ll want to regular check your disk usage using these commands.<\/p>\n

Checking Disk Usage On Linux<\/h2>\n

The utility used to quickly check disk usage on almost all Linux systems is df<\/code>, which stands for \u201cdisk filesystems.\u201d It simply prints out a list of all the filesystems on your system.<\/p>\n

df -hT<\/pre>\n
This command here is invoked with two flags, -h<\/code>\u00a0for \u201chuman readable,\u201d which prints out byte numbers in KB, MB, and GB, and -T<\/code>, which displays the type of the filesystem.<\/p>\n
df<\/code>\u00a0will print out each filesystem alongside the size, how much is used and available, and where it\u2019s mounted to on your system.<\/p>\n
\"\"<\/p>\n
You\u2019ll quickly notice that you probably have a lot more \u201cfilesystems\u201d than you\u2019d expect. This server only has one solid state drive, but has over 20 filesystems. Most of these are backend stuff used for other programs and services, such as compressed\u00a0squashfs<\/code>, virtual\u00a0tmpfs<\/code>\u00a0, and Docker\u2019s overlay<\/code>\u00a0systems used for containers.<\/p>\n
In this example, ext4<\/code>\u00a0is the real drive, which is obvious because it\u2019s mounted at root, but in multi-drive systems that may not be immediately clear. If you want, you can filter this list by specifying which type you want to see with the lowercase -t<\/code>\u00a0flag:<\/p>\n
df -hT -t ext4<\/pre>\n
\"\"<\/p>\n
Or by removing what you don\u2019t want to see manually with the -x<\/code>\u00a0flag:<\/p>\n
df -hT -x squashfs -x overlay -x tmpfs -x devtmpfs<\/pre>\n
\"\"<\/p>\n
You can also ask df<\/code>\u00a0for info on any specific filesystem, even including wildcards to match multiple systems by name:<\/p>\n
df -h \/dev\/md*<\/pre>\n
Or, you can ask it for info on a specific mount, which is most useful for quickly getting the info on your root system:<\/p>\n
df -h \/<\/pre>\n
Monitoring At a Glance<\/h2>\n
Most of the time though, you probably don\u2019t want to remember and type a bunch of commands with specific flags. That\u2019s what the glances<\/code>\u00a0utility<\/a> was made for, and we highly recommend giving it a try.<\/p>\n
It\u2019s basically a replacement for built-in utilities like top<\/code>\u00a0and htop<\/code>, except it displays a lot of different performance metrics about your system, the disks. It\u2019s not included in most Linux distros by default, but it\u2019s open source and can be installed from pip<\/code>, given it\u2019s a Python app.<\/p>\n
sudo pip install glances<\/pre>\n
Then simply run the app to open up the glances<\/code>\u00a0dashboard:<\/p>\n
glances<\/pre>\n
\"\"<\/p>\n
You\u2019ll find in the lower left corner some info on disk usage, including current I\/O speeds, as well as each physical disk\u2019s total usage. Using this, you can easily spot problems with disks filling up before it breaks your system.<\/p>\n
\"\"<\/p>\n
There are plenty of other utilities for monitoring your system, but glances<\/code>\u00a0checks all the boxes, so it\u2019s a pretty nice tool to have.<\/p>\n
Sending Alerts When Your Disk Usage Is Too High<\/h2>\n
The main problem with command line tools is that they require you to be proactive about checking for problems. But problems can pop up unexpectedly, so it\u2019s good to get notified about them beforehand.<\/p>\n
So, the solution is to set up a daily cron<\/code>\u00a0job that will run df<\/code>\u00a0automatically to check the usage on the root system. It will compare this with a set value, and if it\u2019s greater, it\u2019ll send a message.<\/p>\n
#!\/bin\/bash
\nCURRENT=$(df \/ | grep \/ | awk '{ print $5}' | sed 's\/%\/\/g')
\nTHRESHOLD=90
\n
\nif [ \"$CURRENT\" -gt \"$THRESHOLD\" ] ; then
\ncurl -X POST -H 'Content-type: application\/json' --data \"{\"text\":\"Your server `$(hostname)` is currently at ${CURRENT}% disk capacity.\"}\"
\nfi<\/pre>\n
You have plenty of options for how to get messages, and it will depend on your preferred contact. The simplest would be to set up the mail<\/code>\u00a0utility to send you emails from the command line. You can read our article on setting up Postfix<\/a> to handle this for you.<\/p>\n
A much cooler method is to send yourself a message directly on a messaging platform you\u2019re active on, such as setting up Slack notifications from your server, which can be easily done using webhooks with curl<\/code>\u00a0POST requests.<\/p>\n
\"\"<\/p>\n
You can read our article on setting up Slack webhooks for disk space alerts<\/a> to learn more.<\/p>\n
RELATED:<\/strong> How to Setup Slack Notifications for Low Disk Space On Your Server<\/em><\/strong><\/a><\/p>\n<\/div>\n