Basics Tutorial of Linux operating system Commands, File Permission, Crontab Syntax

1. Basics of Linux
Gulshan Verma
Singsys Pte. Ltd.

2. Tux
Tux The Penguin, Mascot of Linux

3.  It is Unix based Operating System developed by community.
 Originated at 1991.
 It is free open source software (FOSS)
 The defining component of Linux is the Linux kernel
 Monolithic
 Micro
 The user interface, also known as the shell, is either a commandline interface (CLI)
 Sh – simple shell
 BASH – Bourne Again Shell
 KSH – Korne Shell
 CSH – C Shell
 SSH – Secure Shell
 Text Editor: VI, Emacs, gEdit, kWrite, Pico, Nano etc.

4. Basics Commands of Linux

5. Basic Commands
$ ls List with filename only
$ ls –l List with all details
$ ls –a List with hidden files
$ ls -la List with hidden files and details

6. Basic Commands (cont)
$ cd /usr/bin Open folder path
$ pwd returns full path of the current
directory
$ which ls
$ whereis ls
$ locate filename
$ find / | something.sh
$ echo
$ cat filename
$ cp
$ mv

7. Basic Commands (cont)
$ mkdir
$ rm
$ chgrp
$ chown
$ chmod
$ tar –cvfp filename.tar /folder
$ unzip filename
$ tar –xvfp filename.tar
$ touch

8. Basic Commands (cont)
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Linux TAR Command
Create linux tar gz (Gzip) archive
tar -czvf myarchive.tgz mydirectory/
-c, –create create a new archive
Note that .tgz is the same thing as .tar.gz
Create linux simple tar archive (withouth compresion)
tar -cvf myarchive.tar mydirectory/
Extracting linux tar archive:
Extract linux tar gz (Gzip) archive
tar -xzvf mystuff.tgz
Extract linux simple tar archive
tar -xvf mystuff.tar
We use -x to extract the files form the tar archive -x, –extract, –get extract files from an archive
Extract linux tar archive to speciefied directory
tar -xvzf filename.tar.gz -C /desired/path
And now let us shortly explain this command
Usage: tar [OPTION]… [FILE]…
Let us check the option used in this example
-c, –create
create a new archive
-z, –gzip, –ungzip
filter the archive through gzip
-v, –verbose
verbosely list files processed
-f, –file=ARCHIVE
use archive file or device ARCHIVE
-C directory file

9. File Permission

10. File Permission (Cont)
 Octal numbers and permissions
 You can use octal number to represent mode/permission:
r : 4
w : 2
x : 1
 0+r+w+x = 0+4+2+1 = 7
 Only Read and write permission on a file in octal is
0+r+w+x = 0+4+2+0 = 6
 Only read and execute permission on a file in octal is
0+r+w+x = 0+4+0+1 = 5
 User
 Group
 Others
= r+w+x = 0+4+2+1 = 7
= r+w+x = 0+4+2+0 = 6
= r+w+x = 0+0+0+1 = 1

11. File Permission (Cont)

12. Creating a crontab file
You can create a crontab file by entering the following
terminal command:
$ crontab –e
To List all the cron job:
$ crontab -l

13. Crontab Syntax

14. Crontab examples
* * * * * <command> #Runs every minute 30
* * * * <command> #Runs at 30 minutes past the hour
45 6 * * * <command> #Runs at 6:45 am every day
45 18 * * * <command> #Runs at 6:45 pm every day
00 1 * * 0 <command> #Runs at 1:00 am every Sunday
00 1 * * 7 <command> #Runs at 1:00 am every Sunday
00 1 * * Sun <command> #Runs at 1:00 am every Sunday
30 8 1 * * <command> #Runs at 8:30 am on the first day of
every month
00 0-23/2 02 07 * <command> #Runs every other hour on the
2nd of July

15. Thank You!
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