Category: Ubuntu

Fix “Can’t Upgrade Due to Low Disk Space on /boot” in Linux

Learn how to resolve the ‘low disk space on /boot’ error during Linux upgrades. Follow step-by-step solutions to free up /boot and complete your system updates.

Your /boot partition is filled with old kernels. It does that sometimes, not sure why it is never fixed. You can easily remove the old kernels if you know which packages they came in.

First check uname -a to check your current version.

Then run the following command:

dpkg -l 'linux-*' | sed '/^ii/!d;/'"$(uname -r | sed "s/\(.*\)-\([^0-9]\+\)/\1/")"'/d;s/^[^ ]* [^ ]* \([^ ]*\).*/\1/;/[0-9]/!d'

This command will list all packages that you no longer need. I don’t like removing them automatically, I like to be in control when it comes to removing kernels. So for every package listed do the following:

sudo apt-get -y purge some-kernel-package

Intermezzo

This intermezzo describes in more detail how the commands work and tries to fix an issue with linux-libc-dev:amd64. Most users can skip this paragraph.

  • dpkg -l 'linux-*' list all packages that have a name starting with ‘linux-‘
  • sed '/^ii/!d; remove all lines that do *not* start withii`
  • uname -r | sed "s/\(.*\)-\([^0-9]\+\)/\1/" find the current running kernel version
  • /'"$(uname -r | sed "s/\(.*\)-\([^0-9]\+\)/\1/")"'/d Remove all lines, except the ones containing the current running kernel version number
  • s/^[^ ]* [^ ]* \([^ ]*\).*/\1/ For each line list only the package name
  • /[0-9]/!d Remove lines that do not contain numbers.

To fix Frederick Nord’s issue I think the command can be amended as follows:

dpkg -l 'linux-*' | sed '/^ii/!d;/'"$(uname -r | sed "s/\(.*\)-\([^0-9]\+\)/\1/")"'/d;s/^[^ ]* [^ ]* \([^ ]*\).*/\1/;/[0-9]/!d;/^linux-\(headers\|image\)/!d'

It basically adds an extra filter:

  • /^linux-(headers\|image)/!d Delete all lines that do not start with linux-headers or linux-image

/Intermezzo

Where some-kernel-package can be replaced with one of the packages listed. Just beware that you don’t remove the kernel packages that are in current use (as listed by the uname -a) eg. sudo apt-get purge -y linux-headers-3.0.0-12 etc.

It can be automated further using the xargs command, but I don’t like that. It is a personal thing. However, here’s the command to do so:

dpkg -l 'linux-*' | sed '/^ii/!d;/'"$(uname -r | sed "s/\(.*\)-\([^0-9]\+\)/\1/")"'/d;s/^[^ ]* [^ ]* \([^ ]*\).*/\1/;/[0-9]/!d' | xargs sudo apt-get -y purge

This is what my /boot looks like, one spare kernel (2.6.38-11) just in case and 3.2.0-24 being current:

$ ls -l /boot
total 59388
-rw-r--r-- 1 root root   730545 Sep 13  2011 abi-2.6.38-11-generic
-rw-r--r-- 1 root root   791023 Apr 25 13:51 abi-3.2.0-24-generic
-rw-r--r-- 1 root root   130326 Sep 13  2011 config-2.6.38-11-generic
-rw-r--r-- 1 root root   140341 Apr 25 13:51 config-3.2.0-24-generic
drwxr-xr-x 3 root root     5120 May 27 17:46 grub
-rw-r--r-- 1 root root 20883146 Oct  1  2011 initrd.img-2.6.38-11-generic
-rw-r--r-- 1 root root 22474219 May  5 09:04 initrd.img-3.2.0-24-generic
drwxr-xr-x 2 root root    12288 Apr 16  2009 lost+found
-rw-r--r-- 1 root root   176764 Nov 27 11:00 memtest86+.bin
-rw-r--r-- 1 root root   178944 Nov 27 11:00 memtest86+_multiboot.bin
-rw------- 1 root root  2656297 Sep 13  2011 System.map-2.6.38-11-generic
-rw------- 1 root root  2884358 Apr 25 13:51 System.map-3.2.0-24-generic
-rw------- 1 root root     1369 Sep 13  2011 vmcoreinfo-2.6.38-11-generic
-rw------- 1 root root  4526784 Sep 13  2011 vmlinuz-2.6.38-11-generic
-rw------- 1 root root  4965776 Apr 25 13:51 vmlinuz-3.2.0-24-generic

And file system usage:

$ df -h /boot
Filesystem Size Used Avail Use% Mounted
/dev/sda5  228M  63M  154M  29% /boot

 

How to Change File Upload Size in Ubuntu via php.ini

Learn how to increase the file upload limit on Ubuntu by editing the php.ini file. Follow this easy guide to update post_max_size and upload_max_filesize.

On Ubuntu server, maximal file size upload limit in php scripts is set to 2Mb as default.  There may be different filesize updated later in php.ini which is not sufficient to upload large database backup in phpMyAdmin.

In order to change that, two things are important,

  • Current upload_max_filesize value
  • Current location of php.ini file

To find current upload_max_filesize value, create a file called ‘pinfo.php’ at your webserver root folder with following content:

phpinfo();

Now, open recently created file in browser via http://localhost/pinfo.php (replace localhost with the servername if necessary) and look for the line

upload_max_filesize 2M

which will show you the actual maximum file size.

To change the upload_max_filesize value, open php.ini file from the location provided in information displayed from pinfo.php file. If php.ini file location is/etc/php5/apache2/php.ini, then open a ssh connection to your server and edit the file /etc/php5/apache2/php.ini as follows

sudo nano /etc/php5/apache2/php.ini

search for “upload_max_filesize” with Ctrl-W and change “2M” to “20M”. Save the file with Ctrl-O and exit with Ctrl-X. Restart the apache server with

sudo /etc/init.d/apache2 restart

and visit again http://localhost/info.php to check if the maximum file size was changed.

There is another way to change upload_max_filesize value for specific project or website only.

If you enabled mod_rewrite you can also put this to your .htaccess file:

php_value upload_max_filesize = 16G
php_value post_max_size = 16G

So, upload_max_filesize value in php.ini file can be changed using .htaccess for project specific and from php.ini file itself for whole server specific.