this is my own personal respository for practice session for learning Shell scripting in deep
dir - /mahilesh/Shell_Scripting/
Architectural Flow for my Setup to make changes
[VS Code on Windows] ←(SSH/SFTP/VSCode Remote)→ [Office Linux Machine] ←(HTTPS/SSH)→ [GitHub]
- whatis: Whatis shows a short particular information about a command.
$ whatis wget
wget (1) - The non-interactive network downloader!
- w: w displays information about currently logged in users and what each user is doing.
$ w
23:35:01 up 2:29, 1 user, load average: 0.72, 1.07, 1.04
USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT
nirjas :1 :1 21:04 ?xdm? 34:58 0.01s /usr/lib
- The flag '-p' is used to create multiple directories or parent directories at once.
$ mkdir -p dir1/dir2/dir3
- Copy directory: The cp command with -r option is used to copy whole directory with its files recursively.
$ cp -r directory1 /home/nirjas/myfiles
- cut: The cut command is used to extract portion of texts from a file.
$ cut -c 4 file.txt
This will show 4th character from each line of that file.
You can also modify it in the follwing way to specify your range.
$ cut -c 4-10 file.txt
- less: When browsing the long log files you can use another very useful command which is called less. If a file content is very large then less is used to view the file contents as a paged manner.
$ less /var/log/syslog
Use the following command to navigate through less:
q - Used to quit out of less and go back to your shell.
Page up, Page down, Up and Down - Navigate using the arrow keys and page keys.
g - Moves to beginning of the text file.
G - Moves to the end of the text file.
/search - You can search for specific text inside the text document. Prefacing the words you want to search with /
h - If you need a little help about how to use less while you’re in less, use help.
- sort: The sort command is used to sort the lines in a text file.
$ sort file1.txt
To do a reverse sort the -r option is used.
$ sort -r file1.txt
Example:-
[root@lvsdevmahileshsbx01 Shell_Scripting]# sort newfile
dwqdwqdwqd
fewfewewewd
fewfewfe fefwef fefwef wefewew fewfewf fefewfewf fef
wdwqdwqd
wdwqdwqwd wdwqqw3e243536754
wqdwqdwq
[root@lvsdevmahileshsbx01 Shell_Scripting]# sort -r newfile
wqdwqdwq
wdwqdwqwd wdwqqw3e243536754
wdwqdwqd
fewfewfe fefwef fefwef wefewew fewfewf fefewfewf fef
fewfewewewd
dwqdwqdwqd
- tr: the tr (translate) command is used to translate a set of character to another one. The following example will convert all lowercase character to uppercase one.
$ tr a-z A-Z
terminal
TERMINAL
- tr: the tr (translate) command is used to translate a set of character to another one. The following example will convert all lowercase character to uppercase one.
$ tr a-z A-Z
terminal
TERMINAL
[root@lvsdevmahileshsbx01 Shell_Scripting]# tr a-z A-Z < newfile
FEWFEWEWEWD
DWQDWQDWQD
WDWQDWQD
- wc: The wc command is used to show count of words, lines and bytes from file respectively.
$ wc file1.txt
To see only the line counts use the following.
$ wc -l file1.txt
- Grep can also be used with regular expressions.
$ grep "one$" file1.txt
The above command will show the lines which are ending the word one. Some other useful regular expressions with grep are as follows.
- Bracket Expressions: You can also specify mutiple words with a particular character by enclosing them with a bracket.
$ grep "swe[ea]t" file.txt
The above command will match this two words sweet and sweat
- To find every line which starts with a capital letter,
$ grep "^[A-Z]" file.txt- To ignore any lines that are commented or blank use the following grep command,
$ sudo grep -vE '^(#|$)'
It's very useful to find lines in a big configuration file.
- To grep only the entries ending with 0*a (like 01a, 02a, 03a, etc.), you can use the following command:
host -l gspt.net | grep -E 'lvsldtdockapp[0-9]+a\.gspt\.net'
ouput:-
[root@lvsprdsa01.gspt.net ~]# host -l gspt.net | grep -E 'lvsldtdockapp[0-9]+a\.gspt\.net'
lvsldtdockapp01a.gspt.net has address 10.124.95.70
lvsldtdockapp02a.gspt.net has address 10.124.95.71
lvsldtdockapp03a.gspt.net has address 10.124.95.75
lvsldtdockapp04a.gspt.net has address 10.124.95.76
Understanding each letter of the command understanding-the-command.
- Grants read (r) permission to others (o), meaning non-owner and non-group users can now read the contents of the file.
chmod o+r file
Everyone can read the file (rw-r--r--), but only the owner can modify it.
Understanding each letter of the command understanding-the-command.
Continue reading from permission based commands - [(https://github.com/Nirzak/All-in-one-Linux-Commands?tab=readme-ov-file#networking-commands)]