Christopher Murray. Linux systems come with a command line utility fsck to check for file system errors. Learn how to use it. Table of Contents. Sometimes bad things happen to good systems.
Introduction to the fsck command The fsck command follows a pattern similar to most Linux commands. You will need to run the command either as root user or use it with sudo. Understanding exit codes for the fsck command This is a list of the codes that may be returned from fsck after inspecting a disk.
Practical usage of the fsck command Now that you are a tad bit familiar with the fsck command, let's see practical use cases of this command. Repair the root file system You cannot unmount the root partition while the system is active.
Most modern Linux versions feature a tool called tune2fs. Send login link. Check your inbox and click the link. Sorry, something went wrong. Please try again. Learn the super powerful and super useful find command with these practical examples. Print a sequence of numbers with specified increment or format with seq command. Keep forgetting Yum commands in Red Hat? Here's a cheat sheet you can download and keep with you for quick reference.
The df command provides an option to display sizes in Human Readable formats by using '-h' prints the results in human readable format e. If you notice all the above commands output, you will see there is no Linux file system type mentioned in the results.
It will display file system type along with other information. For example, the following command will only display ext3 file system.
For example, the following command will only display other file systems types other than ext3. Tags: df linux command , disk usage linux. A space-separated list of unit names that configures the ordering of dependencies between services. This section contains parameters you can use in the [Install] section of a service.
A space-separated list of additional names this service shall be installed under. The names listed here must have the same suffix i. Defines the service as dependent of another service. This usually define the target to trigger an enabled service to run. These options are analogous to the Requires and Wants in the [Units] section. This section contains parameters you can use in the [Service] section of a service unit.
These parameters are specific only to systemd service units. A boolean value that specifies whether the service shall be considered active even if all its processes exited.
Defaults to no. A boolean value that specifies whether systemd should guess the main PID of a service if it cannot be determined reliably. Defaults to yes. An absolute filename pointing to the PID file of this daemon.
Systemd reads the PID of the main process of the daemon after start-up of the service. Systemd does not write to the file configured here, although it removes the file after the service has shut down. A D-Bus bus name to reach this service. A maximum time in seconds for the service to run. Pass infinity the default to configure no runtime limit.
Systemd targets serve a similar purpose to SysVinit runlevels but act a little differently. Each target has a name instead of a number and each serves a specific purpose. Systemd implements some targets by inheriting all of the services of another target and adding additional services to it. The runlevels assigned a specific purpose on vanilla Fedora installs 0, 1, 3, 5, and 6 have a mapping with a specific systemd target.
However, this is not the case for user-defined runlevels 2 and 4. Multi-user, non-graphical. Users can usually login via multiple consoles or via the network. Multi-user, graphical. Usually has all the services of runlevel 3 plus a graphical login. When supported, reloads the config file without interrupting pending operations.
Used to list the services that can be started or stopped Used to list all the services and other units. Used to check whether a service is configured to start or not in the current environment.
Print a table of services that lists which runlevels each is configured on or off. Print a table of services that will be started when booting into graphical mode. Lennart is the primary systemd developer. Interview with the developer. Want to help? Learn how to contribute to Fedora Docs. Edit this Page. Aggressive parallelization capabilities Uses socket and D-Bus activation for starting services Offers on-demand starting of daemons, keeps track of processes using Linux cgroups Supports snapshotting and restoring of the system state Maintains mount and automount points Implements an elaborate transactional dependency-based service control logic.
Usually used to start enabled services on boot. Starting, stopping, and querying systemd services You can perform various management tasks to control systemd services using the systemctl command. Activate a service immediately: systemctl start foo. Modifying existing systemd services This example shows how to modify an existing service.
You are logged in as a user with administrator-level permissions. You have a configured httpd server running through systemd. Systemd services can be modified using the systemctl edit command. Creating new systemd services This example shows how to create a unit file for a custom service. This procedure creates a basic configuration file to control the foo service.
The foo service uses the following parameters: Description A string describing the unit. After Defines a relationship with a second unit. The resulting [Unit] section looks like this:. Type Defines the type of systemd service. ExecStart The command to run to start the service.
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