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broken image path in linux basics

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Kalyanasundaram Somasundaram
2020-11-17 16:09:40 +05:30
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courses/linux_basics/command_line_basics.md
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@@ -18,7 +18,7 @@ for manual pages.
Using \--help to show the documentation for ls command. Using \--help to show the documentation for ls command.
![](/images/linux/commands/image19.png) ![](images/linux/commands/image19.png)
## File System Organization ## File System Organization
@@ -28,7 +28,7 @@ present inside the root directory stores file related to the system.
These directories in turn can either store system files or application These directories in turn can either store system files or application
files or user related files. files or user related files.
![](/images/linux/commands/image17.png) ![](images/linux/commands/image17.png)
bin | The executable program of most commonly used commands reside in bin directory bin | The executable program of most commonly used commands reside in bin directory
sbin | This directory contains programs used for system administration. sbin | This directory contains programs used for system administration.
@@ -62,12 +62,12 @@ At any given moment of time, we will be standing in a certain directory.
To get the name of the directory in which we are standing, we can use To get the name of the directory in which we are standing, we can use
the pwd command in linux. the pwd command in linux.
![](/images/linux/commands/image2.png) ![](images/linux/commands/image2.png)
We will now use the cd command to move to a different directory and then We will now use the cd command to move to a different directory and then
print the working directory. print the working directory.
![](/images/linux/commands/image20.png) ![](images/linux/commands/image20.png)
### cd (change directory) ### cd (change directory)
@@ -77,7 +77,7 @@ command, you can move from one directory to another.
In the below example, we are initially in the root directory. we have In the below example, we are initially in the root directory. we have
then used the cd command to change the directory. then used the cd command to change the directory.
![](/images/linux/commands/image3.png) ![](images/linux/commands/image3.png)
### ls (list files and directories)** ### ls (list files and directories)**
@@ -87,12 +87,12 @@ down all the files and folders present in the given directory.
If we just type ls in the shell, it will list all the files and If we just type ls in the shell, it will list all the files and
directories present in the current directory. directories present in the current directory.
![](/images/linux/commands/image7.png) ![](images/linux/commands/image7.png)
We can also provide the directory name as argument to ls command. It We can also provide the directory name as argument to ls command. It
will then list all the files and directories inside the given directory. will then list all the files and directories inside the given directory.
![](/images/linux/commands/image4.png) ![](images/linux/commands/image4.png)
## Commands for Manipulating Files ## Commands for Manipulating Files
@@ -125,7 +125,7 @@ General syntax of using touch command
touch <file_name> touch <file_name>
``` ```
![](/images/linux/commands/image9.png) ![](images/linux/commands/image9.png)
### mkdir (create new directories) ### mkdir (create new directories)
@@ -138,7 +138,7 @@ General syntax of using mkdir command
mkdir <directory_name> mkdir <directory_name>
``` ```
![](/images/linux/commands/image11.png) ![](images/linux/commands/image11.png)
### rm (delete files and directories) ### rm (delete files and directories)
@@ -158,7 +158,7 @@ Let's try to understand the rm command with an example. We will try to
delete the file and directory we created using touch and mkdir command delete the file and directory we created using touch and mkdir command
respectively. respectively.
![](/images/linux/commands/image18.png) ![](images/linux/commands/image18.png)
### cp (copy files and directories) ### cp (copy files and directories)
@@ -178,18 +178,18 @@ command to create a new directory named "test_directory". We will now
try to copy the "\_test_runner.py" file to the directory we created just try to copy the "\_test_runner.py" file to the directory we created just
now. now.
![](/images/linux/commands/image23.png) ![](images/linux/commands/image23.png)
Do note that nothing happened to the original "\_test_runner.py" file. Do note that nothing happened to the original "\_test_runner.py" file.
It's still there in the current directory. A new copy of it got created It's still there in the current directory. A new copy of it got created
inside the "test_directory". inside the "test_directory".
![](/images/linux/commands/image14.png) ![](images/linux/commands/image14.png)
We can also use the cp command to copy the whole directory from one We can also use the cp command to copy the whole directory from one
location to another. Let's try to understand this with an example. location to another. Let's try to understand this with an example.
![](/images/linux/commands/image12.png) ![](images/linux/commands/image12.png)
We again used the mkdir command to create a new directory called We again used the mkdir command to create a new directory called
"another_directory". We then used the cp command along with an "another_directory". We then used the cp command along with an
@@ -214,7 +214,7 @@ already exists in "test_directory". The mv command will just replace it.
**Do note that the original file doesn't exist in the current directory **Do note that the original file doesn't exist in the current directory
after mv command ran successfully.** after mv command ran successfully.**
![](/images/linux/commands/image26.png) ![](images/linux/commands/image26.png)
We can also use the mv command to move a directory from one location to We can also use the mv command to move a directory from one location to
another. In this case, we do not need to use the '-r' flag that we did another. In this case, we do not need to use the '-r' flag that we did
@@ -227,7 +227,7 @@ directories. Let's see how we can use this command for renaming.
We have first changed our location to "test_directory". We then use the We have first changed our location to "test_directory". We then use the
mv command to rename the ""\_test_runner.py" file to "test.py". mv command to rename the ""\_test_runner.py" file to "test.py".
![](/images/linux/commands/image29.png) ![](images/linux/commands/image29.png)
## Commands for Viewing Files ## Commands for Viewing Files
@@ -247,7 +247,7 @@ online bash shell.
We will create a new file called "numbers.txt" and insert numbers from 1 We will create a new file called "numbers.txt" and insert numbers from 1
to 100 in this file. Each number will be in a separate line. to 100 in this file. Each number will be in a separate line.
![](/images/linux/commands/image21.png) ![](images/linux/commands/image21.png)
Do not worry about the above command now. It's an advanced command which Do not worry about the above command now. It's an advanced command which
is used to generate numbers. We have then used a redirection operator to is used to generate numbers. We have then used a redirection operator to
@@ -261,7 +261,7 @@ The most simplest use of cat command is to print the contents of the file on
your output screen. This command is very useful and can be used for many your output screen. This command is very useful and can be used for many
other purposes. We will study about other use cases later. other purposes. We will study about other use cases later.
![](/images/linux/commands/image1.png) ![](images/linux/commands/image1.png)
You can try to run the above command and you will see numbers being You can try to run the above command and you will see numbers being
printed from 1 to 100 on your screen. You will need to scroll up to view printed from 1 to 100 on your screen. You will need to scroll up to view
@@ -276,13 +276,13 @@ from the top.
In this example, we are only able to see the first 10 lines from the In this example, we are only able to see the first 10 lines from the
file when we use the head command. file when we use the head command.
![](/images/linux/commands/image15.png) ![](images/linux/commands/image15.png)
By default, head command will only display the first 10 lines. If we By default, head command will only display the first 10 lines. If we
want to specify the number of lines we want to see from start, use the want to specify the number of lines we want to see from start, use the
'-n' argument to provide the input. '-n' argument to provide the input.
![](/images/linux/commands/image16.png) ![](images/linux/commands/image16.png)
### tail ### tail
@@ -290,13 +290,13 @@ The tail command displays the last 10 lines of the file by default. We
can include additional arguments to display as many lines as we want can include additional arguments to display as many lines as we want
from the end of the file. from the end of the file.
![](/images/linux/commands/image22.png) ![](images/linux/commands/image22.png)
By default, the tail command will only display the last 10 lines. If we By default, the tail command will only display the last 10 lines. If we
want to specify the number of lines we want to see from the end, use '-n' want to specify the number of lines we want to see from the end, use '-n'
argument to provide the input. argument to provide the input.
![](/images/linux/commands/image10.png) ![](images/linux/commands/image10.png)
In this example, we are only able to see the last 5 lines from the file In this example, we are only able to see the last 5 lines from the file
when we use the tail command with explicit -n option. when we use the tail command with explicit -n option.
@@ -310,7 +310,7 @@ programming languages.
The echo command prints the given input string on the screen. The echo command prints the given input string on the screen.
![](/images/linux/commands/image24.png) ![](images/linux/commands/image24.png)
## Text Processing Commands ## Text Processing Commands
@@ -339,7 +339,7 @@ online bash shell.
We will create a new file called "numbers.txt" and insert numbers from 1 We will create a new file called "numbers.txt" and insert numbers from 1
to 10 in this file. Each number will be in a separate line. to 10 in this file. Each number will be in a separate line.
![](/images/linux/commands/image8.png) ![](images/linux/commands/image8.png)
### grep ### grep
@@ -357,7 +357,7 @@ grep <word_to_search> <file_name>
In this example, we are trying to search for a string "1" in this file. In this example, we are trying to search for a string "1" in this file.
The grep command outputs the lines where it found this string. The grep command outputs the lines where it found this string.
![](/images/linux/commands/image5.png) ![](images/linux/commands/image5.png)
### sed ### sed
@@ -373,7 +373,7 @@ sed 's/<text_to_replace>/<replacement_text>/' <file_name>
Let's try to replace each occurrence of "1" in the file with "3" using Let's try to replace each occurrence of "1" in the file with "3" using
sed command. sed command.
![](/images/linux/commands/image31.png) ![](images/linux/commands/image31.png)
The content of the file will not change in the above The content of the file will not change in the above
example. To do so, we have to use an extra argument '-i' so that the example. To do so, we have to use an extra argument '-i' so that the
@@ -386,12 +386,12 @@ argument. By default, it will sort in increasing order.
Let's first see the content of the file before trying to sort it. Let's first see the content of the file before trying to sort it.
![](/images/linux/commands/image27.png) ![](images/linux/commands/image27.png)
Now, we will try to sort the file using the sort command. The sort Now, we will try to sort the file using the sort command. The sort
command sorts the content in lexicographical order. command sorts the content in lexicographical order.
![](/images/linux/commands/image32.png) ![](images/linux/commands/image32.png)
The content of the file will not change in the above The content of the file will not change in the above
example. example.
@@ -415,12 +415,12 @@ I/O redirection is a very powerful feature.
In the below example, we have used the '>' operator to redirect the In the below example, we have used the '>' operator to redirect the
output of ls command to output.txt file. output of ls command to output.txt file.
![](/images/linux/commands/image30.png) ![](images/linux/commands/image30.png)
In the below example, we have redirected the output from echo command to In the below example, we have redirected the output from echo command to
a file. a file.
![](/images/linux/commands/image13.png) ![](images/linux/commands/image13.png)
We can also redirect the output of a command as an input to another We can also redirect the output of a command as an input to another
command. This is possible with the help of pipes. command. This is possible with the help of pipes.
@@ -428,13 +428,13 @@ command. This is possible with the help of pipes.
In the below example, we have passed the output of cat command as an In the below example, we have passed the output of cat command as an
input to grep command using pipe(\|) operator. input to grep command using pipe(\|) operator.
![](/images/linux/commands/image6.png) ![](images/linux/commands/image6.png)
In the below example, we have passed the output of sort command as an In the below example, we have passed the output of sort command as an
input to uniq command using pipe(\|) operator. The uniq command only input to uniq command using pipe(\|) operator. The uniq command only
prints the unique numbers from the input. prints the unique numbers from the input.
![](/images/linux/commands/image28.png) ![](images/linux/commands/image28.png)
I/O redirection - I/O redirection -
[https://tldp.org/LDP/abs/html/io-redirection.html](https://tldp.org/LDP/abs/html/io-redirection.html) [https://tldp.org/LDP/abs/html/io-redirection.html](https://tldp.org/LDP/abs/html/io-redirection.html)

2
courses/linux_basics/intro.md
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@@ -110,7 +110,7 @@ system by a package manager.
## Linux Architecture ## Linux Architecture
![](/images/linux/commands/image25.png) ![](images/linux/commands/image25.png)
- The Linux kernel is monolithic in nature. - The Linux kernel is monolithic in nature.

114
courses/linux_basics/linux_server_administration.md
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@@ -12,7 +12,7 @@ commands on your own.
- We will be running all the commands on Red Hat Enterprise Linux (RHEL) 8 system. - We will be running all the commands on Red Hat Enterprise Linux (RHEL) 8 system.
![](/images/linux/admin/image19.png) ![](images/linux/admin/image19.png)
- We will run most of the commands used in this module in the above docker container. - We will run most of the commands used in this module in the above docker container.
@@ -41,12 +41,12 @@ id command can be used to find the uid and gid associated with an user.
It also lists down the groups to which the user belongs to. It also lists down the groups to which the user belongs to.
The uid and gid associated with the root user is 0. The uid and gid associated with the root user is 0.
![](/images/linux/admin/image30.png) ![](images/linux/admin/image30.png)
A good way to find out the current user in linux is to use the whoami A good way to find out the current user in linux is to use the whoami
command. command.
![](/images/linux/admin/image35.png) ![](images/linux/admin/image35.png)
**"root" user or superuser is the most privileged user with** **"root" user or superuser is the most privileged user with**
**unrestricted access to all the resources on the system. It has UID 0** **unrestricted access to all the resources on the system. It has UID 0**
@@ -58,11 +58,11 @@ command.
| /etc/shadow | Stores the password associated with the users | | /etc/shadow | Stores the password associated with the users |
| /etc/group | Stores information about different groups on the system | | /etc/group | Stores information about different groups on the system |
![](/images/linux/admin/image23.png) ![](images/linux/admin/image23.png)
![](/images/linux/admin/image21.png) ![](images/linux/admin/image21.png)
![](/images/linux/admin/image9.png) ![](images/linux/admin/image9.png)
If you want to understand each filed discussed in the above outputs, you can go If you want to understand each filed discussed in the above outputs, you can go
through below links: through below links:
@@ -94,13 +94,13 @@ has been created by tailing the /etc/passwd file. The uid and gid are
is /home/shivam and the login shell assigned is /bin/bash. Do note that is /home/shivam and the login shell assigned is /bin/bash. Do note that
the user home directory and login shell can be modified later on. the user home directory and login shell can be modified later on.
![](/images/linux/admin/image41.png) ![](images/linux/admin/image41.png)
If we do not specify any value for attributes like home directory or If we do not specify any value for attributes like home directory or
login shell, default values will be assigned to the user. We can also login shell, default values will be assigned to the user. We can also
override these default values when creating a new user. override these default values when creating a new user.
![](/images/linux/admin/image54.png) ![](images/linux/admin/image54.png)
### passwd ### passwd
@@ -112,11 +112,11 @@ In the above examples, we have not assigned any password for users
\"!!\" in an account entry in shadow means the account of an user has \"!!\" in an account entry in shadow means the account of an user has
been created, but not yet given a password. been created, but not yet given a password.
![](/images/linux/admin/image13.png) ![](images/linux/admin/image13.png)
Let's now try to create a password for user "shivam". Let's now try to create a password for user "shivam".
![](/images/linux/admin/image55.png) ![](images/linux/admin/image55.png)
Do remember the password as we will be later using examples Do remember the password as we will be later using examples
where it will be useful. where it will be useful.
@@ -125,7 +125,7 @@ Also, let's change the password for the root user now. When we switch
from a normal user to root user, it will request you for a password. from a normal user to root user, it will request you for a password.
Also, when you login using root user, the password will be asked. Also, when you login using root user, the password will be asked.
![](/images/linux/admin/image39.png) ![](images/linux/admin/image39.png)
### usermod ### usermod
@@ -134,7 +134,7 @@ home directory or the shell.
Let's try to modify the login shell of user "amit" to "/bin/bash". Let's try to modify the login shell of user "amit" to "/bin/bash".
![](/images/linux/admin/image17.png) ![](images/linux/admin/image17.png)
In a similar way, you can also modify many other attributes for a user. In a similar way, you can also modify many other attributes for a user.
Try 'usermod -h' for a list of attributes you can modify. Try 'usermod -h' for a list of attributes you can modify.
@@ -147,7 +147,7 @@ user, all the information related to that user will be removed.
Let's try to delete the user "amit". After deleting the user, you will Let's try to delete the user "amit". After deleting the user, you will
not find the entry for that user in "/etc/passwd" or "/etc/shadow" file. not find the entry for that user in "/etc/passwd" or "/etc/shadow" file.
![](/images/linux/admin/image34.png) ![](images/linux/admin/image34.png)
## Important commands for managing groups ## Important commands for managing groups
@@ -160,11 +160,11 @@ Commands for managing groups are quite similar to the commands used for managing
| groupdel \<group_name\> | Deletes a group | | groupdel \<group_name\> | Deletes a group |
| gpasswd \<group_name\> | Modifies password for group | | gpasswd \<group_name\> | Modifies password for group |
![](/images/linux/admin/image52.png) ![](images/linux/admin/image52.png)
We will now try to add user "shivam" to the group we have created above. We will now try to add user "shivam" to the group we have created above.
![](/images/linux/admin/image33.png) ![](images/linux/admin/image33.png)
## Becoming a Superuser in Linux ## Becoming a Superuser in Linux
@@ -175,11 +175,11 @@ described in the above section.**
The su command can be used to switch users in linux. Let's now try to The su command can be used to switch users in linux. Let's now try to
switch to user "shivam". switch to user "shivam".
![](/images/linux/admin/image37.png) ![](images/linux/admin/image37.png)
Let's now try to open the "/etc/shadow" file. Let's now try to open the "/etc/shadow" file.
![](/images/linux/admin/image29.png) ![](images/linux/admin/image29.png)
The operating system didn't allow the user "shivam" to read the content The operating system didn't allow the user "shivam" to read the content
of the "/etc/shadow" file. This is an important file in linux which of the "/etc/shadow" file. This is an important file in linux which
@@ -201,7 +201,7 @@ need to be a part of the sudo group.
Let's first switch to the root user using su command. Do note that using Let's first switch to the root user using su command. Do note that using
the below command will need you to enter the password for the root user. the below command will need you to enter the password for the root user.
![](/images/linux/admin/image44.png) ![](images/linux/admin/image44.png)
In case, you forgot to set a password for the root user, type "exit" and In case, you forgot to set a password for the root user, type "exit" and
you will be back as the root user. Now, set up a password using the you will be back as the root user. Now, set up a password using the
@@ -211,7 +211,7 @@ passwd command.
sudo**. In redhat operating systems, this file is not present by sudo**. In redhat operating systems, this file is not present by
default. We will need to install sudo. default. We will need to install sudo.
![](/images/linux/admin/image3.png) ![](images/linux/admin/image3.png)
We will discuss the yum command in detail in later sections. We will discuss the yum command in detail in later sections.
@@ -220,23 +220,23 @@ information. This file stores the rules that users must follow when
running the sudo command. For example, root is allowed to run any running the sudo command. For example, root is allowed to run any
commands from anywhere. commands from anywhere.
![](/images/linux/admin/image8.png) ![](images/linux/admin/image8.png)
One easy way of providing root access to users is to add them to a group One easy way of providing root access to users is to add them to a group
which has permissions to run all the commands. "wheel" is a group in which has permissions to run all the commands. "wheel" is a group in
redhat linux with such privileges. redhat linux with such privileges.
![](/images/linux/admin/image25.png) ![](images/linux/admin/image25.png)
Let's add the user "shivam" to this group so that it also has sudo Let's add the user "shivam" to this group so that it also has sudo
privileges. privileges.
![](/images/linux/admin/image48.png) ![](images/linux/admin/image48.png)
Let's now switch back to user "shivam" and try to access the Let's now switch back to user "shivam" and try to access the
"/etc/shadow" file. "/etc/shadow" file.
![](/images/linux/admin/image56.png) ![](images/linux/admin/image56.png)
We need to use sudo before running the command since it can only be We need to use sudo before running the command since it can only be
accessed with the sudo privileges. We have already given sudo privileges accessed with the sudo privileges. We have already given sudo privileges
@@ -253,15 +253,15 @@ allowed to access the files and resources of another user.
To see the permissions of a file, we can use the ls command. Let's look To see the permissions of a file, we can use the ls command. Let's look
at the permissions of /etc/passwd file. at the permissions of /etc/passwd file.
![](/images/linux/admin/image40.png) ![](images/linux/admin/image40.png)
Let's go over some of the important fields in the output that are Let's go over some of the important fields in the output that are
related to file permissions. related to file permissions.
![](/images/linux/admin/image31.jpg) ![](images/linux/admin/image31.jpg)
![](/images/linux/admin/image57.png) ![](images/linux/admin/image57.png)
### Chmod command in linux ### Chmod command in linux
@@ -285,13 +285,13 @@ allowed and 0 representing False or not allowed.
We will now create a new file and check the permission of the file. We will now create a new file and check the permission of the file.
![](/images/linux/admin/image15.png) ![](images/linux/admin/image15.png)
The group owner doesn't have the permission to write to this file. Let's The group owner doesn't have the permission to write to this file. Let's
give the group owner or root the permission to write to it using chmod give the group owner or root the permission to write to it using chmod
command. command.
![](/images/linux/admin/image26.png) ![](images/linux/admin/image26.png)
Chmod command can be also used to change the permissions of a directory Chmod command can be also used to change the permissions of a directory
in the similar way. in the similar way.
@@ -303,14 +303,14 @@ directories in linux.
Command syntax: chown \<new_owner\> \<file_name\> Command syntax: chown \<new_owner\> \<file_name\>
![](/images/linux/admin/image6.png) ![](images/linux/admin/image6.png)
**In case, we do not have sudo privileges, we need to use sudo **In case, we do not have sudo privileges, we need to use sudo
command**. Let's switch to user 'shivam' and try changing the owner. We command**. Let's switch to user 'shivam' and try changing the owner. We
have also changed the owner of the file to root before running the below have also changed the owner of the file to root before running the below
command. command.
![](/images/linux/admin/image12.png) ![](images/linux/admin/image12.png)
Chown command can also be used to change the owner of a directory in the Chown command can also be used to change the owner of a directory in the
similar way. similar way.
@@ -321,7 +321,7 @@ The chgrp command can be used to change the group ownership of files or
directories in linux. The syntax is very similar to that of chown directories in linux. The syntax is very similar to that of chown
command. command.
![](/images/linux/admin/image27.png) ![](images/linux/admin/image27.png)
Chgrp command can also be used to change the owner of a directory in the Chgrp command can also be used to change the owner of a directory in the
similar way. similar way.
@@ -354,19 +354,19 @@ Steps for setting up a passwordless authentication with a remote host:
Install openssh package which contains all the commands related to ssh. Install openssh package which contains all the commands related to ssh.
![](/images/linux/admin/image49.png) ![](images/linux/admin/image49.png)
Generate a key pair using the ssh-keygen command. One can choose the Generate a key pair using the ssh-keygen command. One can choose the
default values for all prompts. default values for all prompts.
![](/images/linux/admin/image47.png) ![](images/linux/admin/image47.png)
After running the ssh-keygen command successfully, we should see two After running the ssh-keygen command successfully, we should see two
keys present in the \~/.ssh directory. Id_rsa is the private key and keys present in the \~/.ssh directory. Id_rsa is the private key and
id_rsa.pub is the public key. Do note that the private key can only be id_rsa.pub is the public key. Do note that the private key can only be
read and modified by you. read and modified by you.
![](/images/linux/admin/image7.png) ![](images/linux/admin/image7.png)
2. Transferring the public key to the remote host 2. Transferring the public key to the remote host
@@ -374,23 +374,23 @@ Steps for setting up a passwordless authentication with a remote host:
We will look at one of the most common ways of doing it using the We will look at one of the most common ways of doing it using the
ssh-id-copy command. ssh-id-copy command.
![](/images/linux/admin/image11.png) ![](images/linux/admin/image11.png)
Install the openssh-clients package to use ssh-id-copy command. Install the openssh-clients package to use ssh-id-copy command.
![](/images/linux/admin/image46.png) ![](images/linux/admin/image46.png)
Use the ssh-id-copy command to copy your public key to the remote host. Use the ssh-id-copy command to copy your public key to the remote host.
![](/images/linux/admin/image50.png) ![](images/linux/admin/image50.png)
Now, ssh into the remote host using the password authentication. Now, ssh into the remote host using the password authentication.
![](/images/linux/admin/image51.png) ![](images/linux/admin/image51.png)
Our public key should be there in \~/.ssh/authorized_keys now. Our public key should be there in \~/.ssh/authorized_keys now.
![](/images/linux/admin/image4.png) ![](images/linux/admin/image4.png)
\~/.ssh/authorized_key contains a list of public keys. The users \~/.ssh/authorized_key contains a list of public keys. The users
associated with these public keys have the ssh access into the remote associated with these public keys have the ssh access into the remote
@@ -401,13 +401,13 @@ Steps for setting up a passwordless authentication with a remote host:
General syntax: ssh \<user\>@\<hostname/hostip\> \<command\> General syntax: ssh \<user\>@\<hostname/hostip\> \<command\>
![](/images/linux/admin/image14.png) ![](images/linux/admin/image14.png)
### How to transfer files from one host to another host ? ### How to transfer files from one host to another host ?
General syntax: scp \<source\> \<destination\> General syntax: scp \<source\> \<destination\>
![](/images/linux/admin/image32.png) ![](images/linux/admin/image32.png)
## Package Management ## Package Management
@@ -435,17 +435,17 @@ the successor to YUM which is now used in Fedora for installing and
managing packages. DNF may replace YUM in the future on all RPM based managing packages. DNF may replace YUM in the future on all RPM based
linux distributions. linux distributions.
![](/images/linux/admin/image20.png) ![](images/linux/admin/image20.png)
We did find an exact match for the keyword httpd when we searched using We did find an exact match for the keyword httpd when we searched using
yum search command. Let's now install the httpd package. yum search command. Let's now install the httpd package.
![](/images/linux/admin/image28.png) ![](images/linux/admin/image28.png)
After httpd is installed, we will use the yum remove command to remove After httpd is installed, we will use the yum remove command to remove
httpd package. httpd package.
![](/images/linux/admin/image43.png) ![](images/linux/admin/image43.png)
## Process Management ## Process Management
@@ -457,7 +457,7 @@ used to monitor the processes on linux systems.
The ps command is used to know the information of a process or list of The ps command is used to know the information of a process or list of
processes. processes.
![](/images/linux/admin/image24.png) ![](images/linux/admin/image24.png)
If you get an error "ps command not found" while running ps command, do If you get an error "ps command not found" while running ps command, do
install **procps** package. install **procps** package.
@@ -468,17 +468,17 @@ processes on the system by using the below command.
Reference: Reference:
[https://unix.stackexchange.com/questions/106847/what-does-aux-mean-in-ps-aux](https://unix.stackexchange.com/questions/106847/what-does-aux-mean-in-ps-aux) [https://unix.stackexchange.com/questions/106847/what-does-aux-mean-in-ps-aux](https://unix.stackexchange.com/questions/106847/what-does-aux-mean-in-ps-aux)
![](/images/linux/admin/image42.png) ![](images/linux/admin/image42.png)
We can use an additional argument with ps command to list the We can use an additional argument with ps command to list the
information about the process with a specific process ID. information about the process with a specific process ID.
![](/images/linux/admin/image2.png) ![](images/linux/admin/image2.png)
We can use grep in combination with ps command to list only specific We can use grep in combination with ps command to list only specific
processes. processes.
![](/images/linux/admin/image1.png) ![](images/linux/admin/image1.png)
### top ### top
@@ -486,7 +486,7 @@ The top command is used to show information about linux processes
running on the system in real time. It also shows a summary of the running on the system in real time. It also shows a summary of the
system information. system information.
![](/images/linux/admin/image53.png) ![](images/linux/admin/image53.png)
For each process, top lists down the process ID, owner, priority, state, For each process, top lists down the process ID, owner, priority, state,
cpu utilization, memory utilization and much more information. It also cpu utilization, memory utilization and much more information. It also
@@ -504,19 +504,19 @@ The free command is used to display the memory usage of the system. The
command displays the total free and used space available in the RAM command displays the total free and used space available in the RAM
along with space occupied by the caches/buffers. along with space occupied by the caches/buffers.
![](/images/linux/admin/image22.png) ![](images/linux/admin/image22.png)
free command by default shows the memory usage in kilobytes. We can use free command by default shows the memory usage in kilobytes. We can use
an additional argument to get the data in human-readable format. an additional argument to get the data in human-readable format.
![](/images/linux/admin/image5.png) ![](images/linux/admin/image5.png)
### vmstat ### vmstat
The vmstat command can be used to display the memory usage along with The vmstat command can be used to display the memory usage along with
additional information about io and cpu usage. additional information about io and cpu usage.
![](/images/linux/admin/image38.png) ![](images/linux/admin/image38.png)
## Checking Disk Space in Linux ## Checking Disk Space in Linux
@@ -528,19 +528,19 @@ used to view disk space on linux.
The df command is used to display the free and available space for each The df command is used to display the free and available space for each
mounted file system. mounted file system.
![](/images/linux/admin/image36.png) ![](images/linux/admin/image36.png)
### du (disk usage) ### du (disk usage)
The du command is used to display disk usage of files and directories on The du command is used to display disk usage of files and directories on
the system. the system.
![](/images/linux/admin/image10.png) ![](images/linux/admin/image10.png)
The below command can be used to display the top 5 largest directories The below command can be used to display the top 5 largest directories
in the root directory. in the root directory.
![](/images/linux/admin/image18.png) ![](images/linux/admin/image18.png)
## Daemons ## Daemons
@@ -562,7 +562,7 @@ The below examples shows the unit configuration files available at
We are more interested in the configuration file that ends with service We are more interested in the configuration file that ends with service
as these are service units. as these are service units.
![](/images/linux/admin/image16.png) ![](images/linux/admin/image16.png)
### Managing System Services ### Managing System Services
@@ -584,7 +584,7 @@ which can be very useful for viewing system logs and applications logs
in linux. These logs can be very useful when you are troubleshooting on in linux. These logs can be very useful when you are troubleshooting on
the system. the system.
![](/images/linux/admin/image58.png) ![](images/linux/admin/image58.png)
## Applications in SRE Role ## Applications in SRE Role