Operating System Types
1) Single User Single Task -- DOS Microsoft
2) Single User Multi Task -- Windows 10
3) Multi User & Multi Task -- Windoes Server 2008, Unix and Linux
IBM Unix name -- AIX
HP Unix name -- HP-UX
Sun Micro System -- Sun Solaris
Linux Torwalds -- 1991 made kernal called Linux and make it open source
Redhat used that kernal & asked his developers to make Software (Samba.NFS,GUI,LS,CP,Ansible) which could work with this kernel .
Ubuntu & Suse did the same thing.
Kernel + Softwares = Operating System
Commands
Control+Shift +++ To increase size of terminal (RHEL7 & Centros 7)
Control --- To decrease terminal size (RHEL7 & Centros 7)
To Reboot Machine :
reboot (alias)
systemctl reboot (Graceful reboot)
init 6 (for force reboot)
To reboot on specific time
shutdown -r 5:30 & to cancel shutdown : shutdown -c
shutdown -r +15 to reboot after 15 minutes : shutdown -r now
To Shutdown Machine :
systemctl poweroff
poweroff
init 0
shutdown -h 5:30
shutdown -h 15, shutdown -h now
Root directory or Partition (/) has OS installed in it.
It has a total of 19 subdirectories created.
Example :
/root : Home Directory for root user
/boot : all boot files
/etc : system configuration
/bin : commands
/sbin : commands for root user
tmp : temporary data
dev : Hard Disk or Peb drive
home: User's Directory example : /home/mukesh
lib: Libraries of 32 bits
lib64 : Libraries of 64 bits
opt : stores third party softwares
proc : All informations regarding all processes going on system
mnt : information regarding mounting
run : running information regarding all media devices .This is volatile storage
usr : user documentation
PWD : Present working directory
To move to previous location cd" -"
To move back one step cd.. and to move back two cd ../..
To move to root directory cd ~ or simply cd
To see content in directory type "ls" ... by default all directories will show blue and files will shown as black.
To list (see) hidden files l.
root@localhost ~]# l.
. .bash_profile .config .esd_auth .kde
To see all files use "a"
root@localhost ~]# ls -a
. .cache Downloads .local test
root@localhost ~]# ls -al
total 40
dr-xr-x---. 17 root root 4096 Jan 10 23:51 .
dr-xr-xr-x. 17 root root 224 Jan 10 06:44 ..
-rw-------. 1 root root 1910 Jan 10 06:47 anaconda-ks.cfg
-rw-r--r--. 1 root root 18 Dec 29 2013 .bash_logout
-rw-r--r--. 1 root root 176 Dec 29 2013 .bash_profile
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