.. title: File system reminder
.. slug: file-system-reminder
.. date: 2017-12-25 17:51:24 UTC+01:00
.. tags: bash, filesystem
.. category: blog
.. link: 
.. description: 
.. type: text

As I am not manipulating file system everyday, I tend to forget the useful commands, hence this reminder.

.. TEASER_END

Discs and filesystem
====================

Here are some useful commands to manage your discs and filesystems:

- ``less /etc/mtab`` gives information about the filesystems currently mounted
- ``less /etc/fstab`` gives a list of available discs and partitions; in particular, you'll find in this file discs ids (``uuid``) linked to filesystems (``/dev/sda`` or ``/dev/hda`` (``/dev/sd`` being for SCSI and SATA discs whereas ``/dev/hd`` stand for IDE discs))
- ``ls /dev/disk/by-uuid`` gives disc ids list
- ``sudo dumpe2fs /dev/sda1`` provides lots of information about the given filesystem
- ``sudo fdisk -l`` gives information as in ``/etc/mtab`` and ``/etc/fstab``


Reduce reserved space
=====================

By default, 5% of your disk space is dedicated to priority processes and root's ``/home``. If it made sense on older machines with smaller discs, it becomes anoying now we have bigger ones. To reduce this reserved space is therefore very convenient, and very simple with ``tune2fs``, specifying the percentage of your disc you want to reserve:

.. code-block:: bash
    
    tune2fs -m 1 /dev/[partition] 


Corrupted superblock
====================

``fsck`` can be used to check and fix a broken filesystem, and ``mke2fs`` can be used to create a filesystem; ``-j`` option is for ``ext3``:

.. code-block:: bash

    fsck
    mke2fs -j -S /dev/[partition]
    fsck 


Restore a broken filesystem on a USB stick
==========================================

.. code-block:: bash

    sudo /sbin/dosfsck -altrvV /dev/[partition]


Clean-up a partition
======================

.. code-block:: bash

    dd if=/dev/urandom of=/dev/<partition> bs=4096 status=progress