Bash and Node commands (Basics)

PWD

>> pwd

shows/displays the current working directory/base root directory(pwd-print working directory) (GUI-Graphical user interface)

Navigating through the directory

>> cd

Change Directory(navigate (next) to the directory asked for)

>> cd ..

go to the previous directory(takes you back to the previous dir)

>> cd ../..

go to the 2 previous directories

Folders Files

>> ls

Listing all the files/Folders(it basically shows all the files in the directory you are in)

>> mkdir

Make directory(creates a folder)

>> touch index.js

creates a new file with the file-type provided

>> cat index.txt

concatenate
to show & accessing the contents of the file/prints the contents

Vi Command(if you understand this You are going great)

>> vi index.txt

editor is opened. To edit files directly from terminal
Press i -> INSERT mode is ON (You can edit now_
Press ESC+:+w+q+! -> To save the contents edited and exiting in vi
Press ESC -> to come out of INSERT mode
Press :q! -> to escape out of vi (just to get out the vi)

To come out of vi directly -> press esc+:+q+! altogether get back to terminal

Moving Files

>> mv filename folder

Moves file to the provided folder
>> mv folder1 folder2

Move folder1 to folder2

Copy Files

>> cp index.js folder1

can copy file to folder simply
>> cp -r folder1 folder2

Need to raise a flag(-r) to copy folders from 1 to 2

Clear & Exit

>> clear

Clears your terminal
>> exit

Exit from the whole terminal

More fun with ls command

Just for fun to check, look and see files subfiles, directories

 #1. displays all files, folders in folder1(directory-folder)
 ls folder1

 #2. to check the last edited time by whom and file folder owner details
 ls -l
 #gives you
 #permissions no.-of-references owner-name group-owner size modified-day modified-time file/folder-that-modified

 #3. what exactly there in my dir
 ls -l folder1
 #gives you all the modified details of the files folders in the folder1

 #4. what r in sub-dir(files/fol inside the folders)
 ls -r folder1

 #5. last modified in the ls
 ls -t newdir

 #6. last modiefied in the ls with time
 ls -lt newdir

 #7. to get the modified details with the hidden files(denoted by .fName eg: .gitignore etc) sub-dir
 ls -la newdir

 #8. to get the modified details with the hidden files(denoted by .fName eg: .gitignore etc) sub-dir recursively
 ls -lRa newdir

 #9 you wanna check or see the reverse f what you did using timestamp based ordering
 ls -lr newdir

 #10. with size
 ls -s newdir

to do more fun with ls ..,

 #1. recursively giveme all the look modifiys of the directoy
 ls -lR | grep .js

 #2 sub-dir
 ls -l newdir/folder1

 #3. ls command to search for a file by entering only 3-4 letter of it
 ls ind*
 #gives you the index.js index.html files as ind is searched in the present working direcory

 #4. to see dir from the prev directories
 ls ..
 #shows the files/folders from the parent dir

 #5. navigates to previous 3 dir
 cd ../../..

 #6.

More fun with cat command

 #1. to enter into the editor and add some words chars etc
 cat > file.txt
 iuytrdfghj
 #file. ctrl + D to save and exit. ctrl + C to exit.
 #press ctrl+D twice to exit from edit contents of cat
 #prints iuytrdfghj
 # this is just tempporarily now if you again do cat > file.txt it opens as new

More Fun with mv command

#1. move and change filename taht is moved consider style.css is initial name but in moved folder i want it to be as index.css
mv style.css folder1/index.css

More fun with cp command

#1. TO copy a folder from fol1 to fol2 (it cannot copy it displays not copied bcoz its dir hence in that case put -r
cp -r fol1/fol fol2
#now you can see fol in fol1 & fol2 its copied

To wipe/delete file or folder

rm -r fol2
#deletes fol2 folder
rm -r file.txt
#deletes file

ls -l Permissions details

generally look as r--rw-xr in ls -l command above.
they are nothing but read write denoted by r, w, rw.
0. chmod
1. setting permissions for whom u-users, g-group, o-other.
2. adding or removing
3. read-r, write-w, readwrite-rw,x-execute
4. for folder do - before read write but for file nothing

#1. setting the permissions
chmod u+x index.sh
#it means we are adding(+) execute(x) permission to use(u) of file(index.sh) it means setting permission

31. chmod ugo-rwx ---------------------------To add permission to a file.
31. chmod -R ugo-rwx ------------------------To add permission to a folder.
32. chmod u+x filename
33. chmod g+wx filename
34. chmod u-x filename
1-x, 2-w, 4-r
35. chmod 664 foldername

now numeric permissions in this: only permitting group(not noted)

Echo command

$ echo "12345kjhgf"
12345kjhgf

$ echo "hello miss "hi" yeah"
hello miss hi yeah

$ echo 'hiiii'
hiiii

Head Tail commands

$ head file.txt
#displays first 10 rows of the file

$ tail file.txt
#displays last 10 rows of the file

$ head -20 file.txt
#specific set of rows
#first 20 rows displayed

$ tail -n +25 filename | head -n +5
#from 15 to 19 view rows
#pipe operator
#command 1 | command 2
# uses output of command 1 and goestail

word count & history

$ wc file.txt
$ history 
#to view all the command that i've used.

grep command

$ grep "one" filename 
#where "one" has been used in the file.
$ grep "one" filename | wc -l 
#how many times "one" has been used in the file.
$ grep -c "one" filename 
#how many times "one" has been used in the file.
$ grep -h "one" filename 
#where "one" has been used in the file. (case sensitive)
$ grep -hi "one" filename 
#where "one" has been used in the file. (not case sensitive)
$ grep -hir "one" directoryname 
#where "one" has been used in the folder.
$ grep -hin "one" filename 
#where "one" has been used in the file inc line numbers. (not case sensitive)
$ grep -hinw "one" filename 
#where "one" has been used inside a word also individually. {colone, one, One} (case sensitive)
$ grep -o "one" filename 
#only gives us the matched part.
$ grep -w "one" filename 
#where "one" has been used in the file.
$ grep "ERROR" filename 
#will view all the error messages in that file.
$ grep -v "INFO" filename
$ grep -A 5 ERROR filename 
#to view rows after the occurance of ERROR text in a file
$ grep -B 5 ERROR filename 
#to view rows before the occurance of ERROR text in a file
$ grep -C 5 ERROR filename 
#to view rows before and after the occurance of ERROR text in a file.

Sed Command

$ sed -n '/ERROR/ p' filename 
#to print lines with ERROR text.
$ sed 's/ERROR/CRITICAL' filename 
#Replace ERROR with CRITICAL in the file.
$ sed -ibackup 's/ERROR/CRITICAL/' filename 
#Create a backup of the file.
$ sed '3 s/CRITICAL/VERYCRITICAL/' filename 
#Replace CRITICAL with VERYCRITICAL in line number 3.
$ sed '3,5 s/ERROR/CRITICAL/' filename 
#Replace CRITICAL with VERYCRITICAL in line number 3 to line number 5.
$ sed -n '3,/ERROR/ p' filename

awk command

$ awk '/ERROR/{print $0}' filename 
#to print lines with ERROR text.
$ awk '{gsub(/ERROR/, "CRITICAL")}{print}' filename
#Replace ERROR with CRITICAL in the file.
$ awk 'BEGIN {print "LOG SUMMARY\n--------------"} {print} END {print "--------------\nEND OF LOG SUMMARY"}' filename 
#add text in the beginning and ending of a file.
$ awk '{print $1, $2}' filename 
#Print 1st and the 2nd column of the data (file).
$ awk -F "," '{print $1, $2}' filename
$ awk '{count[$2]++} END {print count["ERROR]}' filename 
#Count the occurance of ERROR in second column of the file.
$ awk '{ if ($1 > 1598863888 ) {print $0} }' log.txt 
#view the rows after 1598863888 in first column.

>> node

if you see welcome!---
Your Node got Installed
This command opens Node shell and to exit node shell press ctrl+c twice then you will get back to bash/git Terminal
```
 $ which npm
 /usr/bin/npm
 $ npm --version
 6.13.7
```
>> node index.js

compiles & Runs the JS file and prints the contents
>> nvm

Node Version Manager
>> npm
this npm command gives the list of commands you can have with it
Node Package Manager - manages packages

NPM Registry - collection of all external packages
>> npm install express

Installs express package from external to your local machine and you may see package.json, nodeModule files

for all the packages and names guide, see on: https:/npmjs.com/package

To run the packages from that URL to on your local machine >> npm install name-of-lib

>> node package m

same often

Bash and Node commands (Basics)

Table of contents

Bash related Commands

Node related Commands