Exploring The System Flashcards
How do you list the content of a directroy?
ls
How do you determine a file type?
file filename
How can you veiw the contents of a file?
less
How do we change the format of a commands output?
We change the format of a command output by using Options and Arguments.
How do list the content of multiple directories?
ls ~ /usr /var Issue a ls to tell the system to list the content of each directory listed seperated by a space
What does ls -a (–all) do?
List all files, even those that begin with a period, which are normally hidden
What does ls - l do?
Displays results in long form
What does ls - d (–directory) do?
When used in conjunction with -l it will list the details of the direcotry rather than its contents
What does ls -h (human-readable) do?
In long form listing, displays the file size in human readable format rather than bytes.
What does ls -F (–classify) do?
This option appends an indicator character to the end of each listed name.
What does ls -r (–reverse) do?
Displays results in reverse order.
What does ls -s do?
Sorts by file size.
What does ls -t do?
Sorts by modification time.
What is a common ls command with options
ls -ltr This will show the contents of a directory in long format sorted by time then display in reverse order.
What are some of the common ways to navigate less
“Page up or b Scroll back one page”
“Page Down or space Scroll forward one page”
“Up Arrow” Scroll up one line”
How can we view the contents of a text file?
less
/
The root directory. Where everything begins.
/bin
Contains binaries (programs) that must be present for the system to boot and run.
/boot
Contains the Linux kernel, initial RAM disk image (for drivers needed at boot time), and the boot loader.
/boot/grub/grub.conf or menu.lst
used to configure the boot loader
/boot/vmlinuz
the linux kernel
/etc
The /etc directory contains all of the system-wide configuration files. It also contains a collection of shell scripts which start each of the system services at boot time. Everything in the directory should be readable text.
/etc/crontab
A file that defines when automated jobs will run
/dev
This is a special directory which contains device nodes. “Everything is a file” also applies to devices. Here is where the kernel maintains a list of all the devices it understands.
/etc/fstab
a table of storage devices and their associated mount points
/etc/passwd
a list of the user accounts
/lib
Contains shared library files used by the core system programs. These are similar to DLLs in Windows.
/home
In normal configurations, each user is given a directory in /home. Ordinary users can only write files in the home directories. This limitation protects the system from errant user activity.
/lost+found
Each formatted partition or device using a Linux file system such as ext3, will have this directory. It is used in the case of a partial recovery from a system corruption event. Unless something really bad has happened to your system this directory will remain empty.
/media
On modern Linux systems the /media directory will contain the mount points for removable media such as USB drives CD-ROMs, etc. that are mounted automatically at insertion.
/opt
The /opt direcotry is used to install “optional” software. This is mainly used to hold commercial software products that may be installed on your system.
/proc
The /proc directory is special. It’s not a real file system in the sense of files stored on your hard drive. Rather, it is a virtual file system maintained by the Linux Kernel. The “files” it contains are peepholes into the kernel itself. The files are readable and will give you a picture of how the kernel sees your computer.
/mnt
On older Linux systems, the /mnt directory contains mount points for removable devices that have been removed manually.
/root
This is the home directory for the root account
/sbin
This directory contains “system” binaries. These are programs that perform vital system task that are generally reserved for the superuser.
/tmp
The /tmp directory is intended for the storage of temporary, transient files created by various programs. Some configurations cause this directory to be emptied each time the system is rebooted.
/usr
The /usr directory tree is likely the largest one on a Linux system. It contains al the programs and support files used by regular users.
/usr/bin
/usr/bin contains the executalbe programs installed by you linux distrobution. It is not uncommon for this directory to hold thousands of programs.
/usr/lib
The shared libraries for the programs in /usr/bin
/usr/sbin
Contains more system administration programs
/usr/local
The /usr/local tree is where programs that are not included with your distorbution but are intended for system wide use are installed. Programs compied from source code are normally installed in /usr/local/bin . On a newly installed Linux system, this tree exists, but will be empty until the system administrator puts something in it.
/usr/share
/usr/share contains all the shared data used by the programs in /usr/bin. This includes things like default configuration files, icons, screen backgrounds, sound files, etc.
/usr/share/doc
Most packaged installed on the system will include some kind of documentation. In /usr/share/doc, we will find documentation files organized by package.
/var
With the exception of /tmp and /home, the directories we have looked at so far remain releatively static, that is, their contents don’t change. The /var directory tree is where data that is likely to change is stored. Various databases, spool files, user mail, etc. are located here.
/var/log
/var/log contains log files, records of various system activity. These are very important and should be monitore from time to time. The most useful one is the /var/log/messages. Note that for security reason on some systems, you must be supersuser to veiw log files.
