Category: Linux

Find which directory is using most inodes

Oneliners to find which directory on the server is using most inodes:

To find how many inodes are used per each directory on certain path run:

find ./ -maxdepth 1 -type d -print0 | while IFS= read -r -d $'\0' dir; do echo "$(find "$dir" | wc -l) "$dir""; done| sort -n | tail

Last line will show the path being searched and second to last line will be directory with most inodes, then cd to that directory and run again to see which subfolder is using most inodes.

To get directory with most inodes immediately, without the need to cd in each directory you can run following:

find ./ -type d -print0 | while IFS= read -r -d $'\0' dir; do echo "$(stat -t "$dir" | awk '{print$2}') "$dir""; done | sort -n | tail

This will not show the number of inodes used, only which directory has most inodes in it.
Oneliner from top can be used to get exact number of inodes in it.

Small WordPress backup script

Simple backup script written in bash, for WordPress on Linux, that will dump MySQL database used by WordPress site and create tar.gz file consisting of WordPress site files and database dump

#!/bin/bash

BKPDIR=/local/backup/directory
WEBROOT=/wordpress/install/directory/

DBUSER=$(grep DB_USER $WEBROOT/wp-config.php | awk -F\' '{print$4}')
DBNAME=$(grep DB_NAME $WEBROOT/wp-config.php | awk -F\' '{print$4}')
DBPASSWORD=$(grep DB_PASSWORD $WEBROOT/wp-config.php | awk -F\' '{print$4}')
DBDUMP="$BKPDIR""$DBNAME"_$(date +"%Y-%m-%d-%H-%M").sql

#In case you want to rsync backups to remote server
RUSER=remoteuser
RHOST=remoteserver
RDIR=/remote/backup/directory/
RSSHPORT=22

mysqldump -u $DBUSER -p$DBPASSWORD $DBNAME > $DBDUMP

tar -czvf "$BKPDIR"wpbackup_$(date +"%Y-%m-%d_%H-%M").tar.gz $WEBROOT $DBDUMP

rsync -az $BKPDIR -e "ssh -p $RSSHPORT" $RUSER@$RHOST:$RDIR

It will create two backup files, one for database dump in format that looks like “dbname_2018-01-04-06-00.sql” and one tar.gz file that will look like “wpbackup_2018-01-04_06-00.tar.gz”.

Script can be saved as wpbackup.sh and put in crontab to run at a certain time like 6:00AM.

0 6 * * * /path/to/script/wpbackup.sh 2>/dev/null

It can also be run manually with bash wpbackup.sh

Reset SSH, and find SSH port on cPanel/WHM server

If you lock yourself out of SSH access to your cPanel server or if you do not know on which port your SSH server is running there are several ways you can gain back SSH access to your server.

Flush iptables

If your  IP got locked out in iptables you can use one of cPanel autofixer scripts to flush all iptables chains so your IP can reach SSH on your server again.

Script can be called by adding “scripts2/doautofixer?autofix=iptablesflush” to the end of the WHM url in your browser, and should look something like this:

https://server.domain.tld:2087/cpsess1290981925/scripts2/doautofixer?autofix=iptablesflush

flushing iptables

Reset SSH

If you SSH server is not accessible because of a broken configuration or anything else and is not restarting properly through Home »Restart Services »SSH Server (OpenSSH) in WHM you can try starting safesshrestart script which will kill any running instance of sshd and start a new process on port 22, or if that port is taken on first available port after that, like port 23.

Script can be started by adding “scripts2/doautofixer?autofix=safesshrestart” to the end of your WHM url and should look something like this:

https://server.domain.tld:2087/cpsess1290981925/scripts2/doautofixer?autofix=safesshrestart

Pay attention to the output in WHM when script runs, it will say on which port was SSH started.

safesshrestart

Find out your SSH port

If you are not sure on which port is your SSH server running you can find that out on two ways.

You can use the Restart Services part of WHM and restart SSH by going to Home »Restart Services »SSH Server (OpenSSH) in WHM and watching the output in WHM after you restart SSH, it will say on which port is SSH listening.

Other option is to use an API call to show the port.
You can do that by adding “xml-api/cpanel?user=cpanel&cpanel_xmlapi_apiversion=1&cpanel_xmlapi_module=SSH&cpanel_xmlapi_func=getport” to the end of your WHM url which should look something like this:

https://server.domain.tld:2087/cpsess1290981925/xml-api/cpanel?user=cpanel&cpanel_xmlapi_apiversion=1&cpanel_xmlapi_module=SSH&cpanel_xmlapi_func=getport

You can find out more about WHM autofixers on following link:

https://documentation.cpanel.net/display/ALD/WHM+FAQ#WHMFAQ-WhatistheWHMAutofixer?

Full list of all autofixers can be found here:

http://httpupdate.cpanel.net/autofixer/

Ubuntu shows “No Bootable Device” after installation in UEFI mode

When doing a fresh install of Ubuntu 16.04, or any other version of Ubuntu or Linux, after the install you might get your laptop or desktop machine not booting the installed OS, but instead returning “No Bootable Device” message, if laptop is set to UEFI mode.

You might be presented with this image after rebooting your laptop, after a successful OS install.

No Bootable Device message
No Bootable Device message

To resolve this issue reboot your laptop and enter BIOS.

There go to “Select and UEFI file as trusted for executing:” and press Enter key.

BIOS Select UEFI file

Once there choose HDD1.

BIOS select Hard Drive

Then choose <EFI>.

BIOS select EFI

Then you should be able to see <ubuntu> or possibly some other name of your Linux installation.

BIOS select Ubuntu

Then choose shimx64.efi

BIOS select shimx64

And then choose Yes when asked if you want to add this file to allowable database.

BIOS add file to database

Reboot your laptop and you should now be able to boot your OS normally.

VirtualBox returns “Kernel driver not installed” on Ubuntu

When trying to run VirtualBox on Ubuntu 16.04, or some other version of Linux, you might get a following type an error message, when trying to start a virtual machine, you just created on a fresh installation of VirtualBox.

VirtualBox might return error saying that it failed to open a session for  the virtual machine.

Details of error message will say that virtual machine has terminated unexpectedly during startup with exit code 1 (0x1).

VirtualBox failed session message
VirtualBox failed session message

You will also get a “Kernel driver not installed (rc=-1908” message.

VirtualBox Kernel driver error
VirtualBox Kernel driver error

Error will say “The VirtualBox Linux kernel driver (vboxdrv) is either not loaded or there is a permission problem with /dev/vboxdrv.”

Error message will ask you to try to reinstall the kernel module by executing /sbin/vboxconfig as root, to reinstall the module, which could fail to complete successfully when you try to run the command in terminal.

One of the possible causes of this type of behavior is that you have Secure Boot enabled in your BIOS on the host machine, which is preventing the install of third-party drivers, and causing issues with VirtualBox installation, which fails to install all kernel modules.

To resolve this error, disable Secure Boot in your BIOS, and then try to run /sbin/vboxconfig command as root, or reinstall VirtualBox, with Secure Boot disabled, to install all the necessary modules.