Working with Files and Directories In Unix(Shell Scripting).

commands used in Unix in order to read, write and access a file and directories

Working with files and directories:

How to know the location where I am:

$ pwd

• pwd means present working directory.

To view the files and directory in present working directory:

$ ls

Options:

$ ls -l

$ ls -r

To Navigate one directory from another directory:

• By using cd (change directory) command

for example:

$ cd directory_name (to go to any any directory)

$ cd .. (Go back to previous directory)

$ cd ../.. (Go back to previous-to-previous directory)

$ cd ~ (go to parent directory)

To create a directory:

• By using mkdir(make directory) command.

Syntax: -

$ mkdir directory_name 
# don't give space in name of directory if you give space, it will create two directory)

for example:

How to create a file:

There are 3 ways of creating a file

1. By using touch command.
2. By using vi editor.
3. By using cat command:

1. By using touch command

• we can create an empty file by using touch command

e.g.:

$ touch file_name

2. By using vi editor:

• we can create a file by using vi editor and we can add up content too at the same time.

3. By using cat command:

• create a file.
• you could add new contents, append with existing content, overwrite the contents.
• read the file

By using cat command, you can do 3 operations:

> : Override

>> : Append

< : read

A) $ cat > filename

• kernel will check whether a file with the provided name is already present in the current pwd.
  if yes, it is present
  → then it will re write or override the new contents to the existing contents
  else No, the file is NA
  → then it will create a file with the provided name and write in the new contents
• to mark the EOF (end of file) ctrl + d → close it
  ctrl + c — forcefully quitting the operation.

e.g., →

B) $ cat < filename or cat filename
→ read the contents of the file

e.g., →

C) cat >> filename

• kernel will check whether a file with the provided name is already present in the current pwd.
• if yes, it is present
  → it will append the new contents to the existing contents.
  else No, the file is NA.
  → it will create a file with the provided name and write in the new contents.

e.g., →

OPTIONS:

-n → number all the lines
-b → number of nonblank lines
-s →squeeze the multiple \n with a single \n.

How to remove directory :

• by rmdir command : it is used to remove empty directory.
• by rm -rf command : if directory contains some files then we can remove it forcefully by this command.
• Syntax of rmdir :

$ rmdir new_created_directory

for example :

Syntax for rm :

• “rm” command can be used to remove files and non empty directories.

$ rm options file_name

• Options :

for example :

$ rm -i file3

for e.g. :

Thank you…