-
To change the owner of a file
sudo chown arafat file.txt -
To change the group of a file
sudo chown :root file.txt -
To change both the owner and group of a file
sudo chown arafat:roo7 file.txt
Note: Its importance appears in system 2 course, not here
- Process has an ID which consists of up to 5 digits
- Processes have two types:
- Foreground : must be finished before user could use terminal {ex: [ls]}
- Background : allow user to continue to use the terminal
First process that starts on system called -> systemd with ID = 0
Note: a process that ends with [d] means its a background one
-
Background process = Daemons Process
-
When a process create another process, first one is called parent while created one is called child
-
Show all processes running in the system
ps -ef
O/P: UID|PID|PPID x y z
UID -> User who created this process PID -> Process ID PPID -> Parent process {who created it}
-
Show processes that are created by specific user
ps -u <Username {OR} UserID> -
To make terminal sleep for [n] seconds {no command will be executed at this time} $ sleep n
sleep 5 -
Start a process in Background
sleep 1000 &
-> [&] sign
Note: to terminate a running command (like $ sleep 1000) use: Ctrl + c --> It terminates process Ctrl + z --> It stops process {pause}
kill -option <ProcessID>
option {Called signals} may be :
- -15 : softkill (terminal) {if no other process depends on it}
- -9 : hardkill, used when [-15] is not working {Force}
- -19 : stop a process (as Ctrl + z)
- -18 : Resume a process
EX:
kill -9 1272
- Terminate all sleep process in system {pkill}
pkill -9 sleep
- Show all processes running in background only (when you used [&] in command)
$ jobs
O/P :
[1] + Running sleep 1000 &
-
Transfer a process from background to foreground
fg %n
EX: fg %1 -> Number [1] is in Line #77
-
Resume a process
kill -18 1633 -
Search for a specific process by its name {like $ grip command}
pgrep -x -u 1000 -l docker
-x : Search for an exact name { docker != dockermanager}
-u : Search for a process with its UserID who created it
-l : print PID + Process Name
-
A service is an application or set of applications that run in Background waiting to be used
-
Show services in system
systemctl
-> You can use it to show/stop/start a service {OR}
service <ServiceName> <Action>
sudo systemctl status docker
sudo systemctl stop docker
sudo systemctl start docker
-
Enable/Disable auto start of a service when system boots
sudo systemctl enable/disable docker
- Each file system (partition) has an Inode table, in which all of the used Inodes are mapped to particular files
- Linux stores administrative data about files in nodes
- Information stored in the Inode table are :
- Size
- DeviceID
- UID
- GID
- Mode
- Time Stamp
- pointer to date
- type of file
- file permission
- Number of hard links
-
Inode tables do not contains filename of its content
-
Names are stored in the Directory
-
Each filename knows which Inode it has
-
An Inode does not know which name it has, it just know how many names are associated with the Inode, those names are referred to as {Hard Links}
-
To know Inode Number of a File/Directory
ls -id/-i <Filename/DirName>
-> -id : For a Directory -> -i : For a File
-> Soft link (Symbolic) is like shortcut in windows
-
Create a Soft Link
ln -s file1.txt softlink_file1.txt
-> ln : stands for links -> -s : for softlink
Note: Inode Number of [file1.txt] != [softlink_file1.txt]
ls -l softlink.txt
O/P -> L rwx|rwx|rwx -> [L] for link
-
If main file is deleted then softlink file become useless
-
Create Hard Link
ln file2.txt hardlink_file2.txt
Note: Inode Number of [file2.txt] != [hardlink_file2.txt] also Hardlinks used to backup files
Disk
----
---- <------ File <----- Softlink
----
Disk
----
---- <------ File
---- <----- Hardlink
(Refer to same partition in Disk)
Note : - You cannot use hardlink across partitions because each partition has its own Inode table
-
You cannot make a hard link for a Directory
-
To get information about Inode of your partition
df -i <FileSystem>
EX: $ df -i /dev/sdu5
-
We use {fdisk} utiltiy to manage file system, like creating or deleting a partition
-
To list your partitions and storage disks informations
sudo fdisk -l{OR}
df -h -
Modify a partition
sudo fdisk -option <DiskName>
option is for: -m -> View help -d -> Delete a partition -l -> List known partition types -n -> Add a new partition -p -> Print the partition table -q -> Quits without saving changes -w -> Write table to disk and then exit
EX: $ sudo fdisk -l /dev/sdu
-
Then run $ partprobe
-
To format the newly created partition
mkfs -t ext4 /dev/sdu3
-> ext4 : type of partition
-
Create a mount point for the partition
mkdir /my_partition -
Mount newly created partition
mount /dev/sdu3 /my_partition
-
The {tar} command archive files to and extract files from a single file called a tar file
tar -option <ArchiveName> file1,file2,...
option is for: -c -> Create a new tar file {archiving} -t -> List table of content of a tar file -x -> Extracts files from the tar command -f -> Specify the archive file {used with archiving files or unarchiving files} -v -> Verbase mode {more information}
-
Create a tar file{archive}
tar -cf archive.tar file1
-Show files in an archive file
tar -tf archive.tar file1
-
To extract files
tar -xf archive.tar -
To extract files in another path
tar -xf archive.tar -C /home/arafat/Documents
{OR} just execute command in this path
Note:
touch file1; mkdir Dir1
{OR} touch file1 && mkdir Dir1 -> To execute more than one command in the same line, but for [&&] sign if the first command have an error second one wont be executed {like Programming}
-
To compress a file
gzip file1
-> File will be taken to create zip file {file will disappear}
gzip Dir1 (X) -> Cannot make a compressed Directory
-> Create a zipped & compressed file
tar -cfz file.tar.gz dir7 file2.txt
-> -z : stands for zip
-
Unzip a zipped file
gunzip file.tar.gz
-> Then file will become file.tar {use again $ tar -fx command}
-
To make them just in one step
tar -xf file.tar.gz